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Bis[μ-bis­­(2,6-diiso­propyl­phen­yl) phosphato-κ2O:O′]bis­­[(2,2′-bi­pyridine-κ2N,N′)lithium] toluene disolvate and its catalytic activity in ring-opening polymerization of -caprolactone and L-dilactide

aA.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 29 Leninsky Prospect, 119991, Moscow, Russian Federation, bMoscow Institute of Physics and Technology, Department of Biological and Medical Physics, 9 Institutskiy Per., Dolgoprudny, Moscow Region, 141701, Russian Federation, cG.V. Plekhanov Russian University of Economics, 36 Stremyanny Per., Moscow, 117997, Russian Federation, dChemistry Department, M.V. Lomonosov Moscow State University, 1 Leninskie Gory Str., Building 3, Moscow 119991, Russian Federation, and eN.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prospect, Moscow 119991, Russian Federation
*Correspondence e-mail: mminyaev@mail.ru

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 24 April 2019; accepted 14 May 2019; online 21 May 2019)

The solvated centrosymmmtric title compound, [Li2(C24H34O4P)2(C10H8N2)2]·2C7H8, was formed in the reaction between {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) and 2,2′-bi­pyridine (bipy) in toluene. The structure has monoclinic (P21/n) symmetry at 120 K and the asymmetric unit consists of half a complex mol­ecule and one mol­ecule of toluene solvent. The diaryl phosphate ligand demonstrates a μ-κO:κO′-bridging coordination mode and the 2,2′-bi­pyridine ligand is chelating to the Li+ cation, generating a distorted tetra­hedral LiN2O2 coordination polyhedron. The complex exhibits a unique dimeric Li2O4P2 core. One isopropyl group is disordered over two orientations in a 0.621 (4):0.379 (4) ratio. In the crystal, weak C—H⋯O and C—H⋯π inter­actions help to consolidate the packing. Catalytic systems based on the title complex and on the closely related complex {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) display activity in the ring-opening polymerization of -caprolactone and L-dilactide.

1. Chemical context

Various d- and f-metal complexes with disubstituted organophosphate ligands are currently being studied, for example, as model compounds to explore the role of biometals in biological systems, including complexes that mimic the functions, structure and reactivity of active centers of enzymes in order to create models of biologically active metal centers (Kövári & Krämer, 1996[Kövári, E. & Krämer, R. (1996). J. Am. Chem. Soc. 118, 12704-12709.]; Lipscomb & Sträter, 1996[Lipscomb, W. N. & Sträter, N. (1996). Chem. Rev. 96, 2375-2434.]; Hegg & Burstyn, 1998[Hegg, E. L. & Burstyn, J. N. (1998). Coord. Chem. Rev. 173, 133-165.]; Hegg et al., 1999[Hegg, E. L., Mortimore, S. H., Cheung, C. L., Huyett, J. E., Powell, D. R. & Burstyn, J. N. (1999). Inorg. Chem. 38, 2961-2968.]; Atkinson & Lindoy, 2000[Atkinson, I. M. & Lindoy, L. F. (2000). Coord. Chem. Rev. 200-202, 207-215.]; Deck et al., 2002[Deck, K. M., Tseng, T. A. & Burstyn, J. N. (2002). Inorg. Chem. 41, 669-677.]; Reichenbach-Klinke & König, 2002[Reichenbach-Klinke, R. & König, B. (2002). J. Chem. Soc. Dalton Trans. pp. 121-130.]; Fry et al., 2005[Fry, F. H., Fischmann, A. J., Belousoff, M. J., Spiccia, L. & Brügger, J. (2005). Inorg. Chem. 44, 941-950.]; Dey et al., 2012[Dey, R., Bhattacharya, D., Karmakar, P. & Ghoshal, D. (2012). Polyhedron, 48, 157-166.]; Sato et al., 2012[Sato, K., Ohnuki, T., Takahashi, H., Miyashita, Y., Nozaki, K. & Kanamori, K. (2012). Inorg. Chem. 51, 5026-5036.]), as catalysts for various catalytic processes, e.g. alkene cyclo­propanation and carbene insertions (Lacasse et al., 2005[Lacasse, M.-C., Poulard, C. & Charette, A. B. (2005). J. Am. Chem. Soc. 127, 12440-12441.]; Hrdina et al., 2013[Hrdina, R., Guénée, L., Moraleda, D. & Lacour, J. (2013). Organometallics, 32, 473-479.]), polymerization of conjugated dienes (Anwander, 2002[Anwander, R. (2002). in Applied Homogeneous Catalysis with Organometallic Compounds, edited by B. Cornils & W. A. Herrmann, pp. 974-1013. Weinheim: Wiley-VCH.]; Friebe et al., 2006[Friebe, L., Nuyken, O. & Obrecht, W. (2006). Adv. Polym. Sci. 204, 1-154.]; Kobayashi & Anwander, 2001[Kobayashi, S. & Anwander, R. (2001). Lanthanides: Chemistry and Use in Organic Synthesis. Topics in Organometallic Chemistry, Vol. 2, pp. 1-307. Berlin, Heidelberg: Springer-Verlag.]; Minyaev et al., 2018a[Minyaev, M. E., Tavtorkin, A. N., Korchagina, S. A., Bondarenko, G. N., Churakov, A. V. & Nifant'ev, I. E. (2018a). Acta Cryst. C74, 590-598.],b[Minyaev, M. E., Korchagina, S. A., Tavtorkin, A. N., Churakov, A. V. & Nifant'ev, I. E. (2018b). Acta Cryst. C74, 673-682.],c[Minyaev, M. E., Korchagina, S. A., Tavtorkin, A. N., Kostitsyna, N. N., Churakov, A. V. & Nifant'ev, I. E. (2018c). Struct. Chem. 29, 1475-1487.]; Nifant'ev et al., 2013[Nifant'ev, I. E., Tavtorkin, A. N., Shlyahtin, A. V., Korchagina, S. A., Gavrilenko, I. F., Glebova, N. N. & Churakov, A. V. (2013). Dalton Trans. 42, 1223-1230.], 2014[Nifant'ev, I. E., Tavtorkin, A. N., Korchagina, S. A., Gavrilenko, I. F., Glebova, N. N., Kostitsyna, N. N., Yakovlev, V. A., Bondarenko, G. N. & Filatova, M. P. (2014). Appl. Catal. Gen. 478, 219-227.]; Zhang et al., 2010[Zhang, Z., Cui, D., Wang, B., Liu, B. & Yang, Y. (2010). Struct. Bond 137 49-108.]) acrylo­nitrile (Minyaev et al., 2018d[Minyaev, M. E., Tavtorkin, A. N., Korchagina, S. A., Nifant'ev, I. E. & Churakov, A. V. (2018d). Acta Cryst. E74, 543-547.]) and dilactide (Nifant'ev et al., 2013[Nifant'ev, I. E., Tavtorkin, A. N., Shlyahtin, A. V., Korchagina, S. A., Gavrilenko, I. F., Glebova, N. N. & Churakov, A. V. (2013). Dalton Trans. 42, 1223-1230.]) and inhibition of thermal decomposition of polydi­methyl­siloxanes (Minyaev et al., 2018a[Minyaev, M. E., Tavtorkin, A. N., Korchagina, S. A., Bondarenko, G. N., Churakov, A. V. & Nifant'ev, I. E. (2018a). Acta Cryst. C74, 590-598.],e[Minyaev, M. E., Tavtorkin, A. N., Korchagina, S. A., Nifant'ev, I. E., Churakov, A. V., Dmitrienko, A. O. & Lyssenko, K. A. (2018e). Acta Cryst. E74, 1433-1438.]). Synthetic precursors for these com­plexes are the corresponding alkali metal organophos­phate derivatives, whose structures are still poorly explored.

[Scheme 1]

Recently we have reported on the structure of the lithium salt {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH), (I)[link], having the same ligand (Minyaev et al., 2015[Minyaev, M. E., Nifant'ev, I. E., Tavtorkin, A. N., Korchagina, S. A. & Zeynalova, S. S. (2015). Acta Cryst. E71, 443-446.]) as in the title compound. Attempts to use this salt to produce Tb and Eu phosphate complexes with luminescent properties have led to complexes having coordinated methanol mol­ecules and possessing very low quantum yields (unpublished results). The presence of the MeOH mol­ecules and therefore undesirable Ln—O—H bonds usually noticeably decreases the quantum yield because of quenching luminescence (Bünzli & Piguet, 2005[Bünzli, J.-C. G. & Piguet, C. (2005). Chem. Soc. Rev. 34, 1048-1077.]; Bünzli, 2017[Bünzli, J.-C. G. (2017). Eur. J. Inorg. Chem. pp. 5058-5063.]; Yan et al., 1995[Yan, Y., Faber, A. J. & de Waal, H. (1995). J. Non-Cryst. Solids, 181, 283-290.]; Sy et al., 2016[Sy, M., Nonat, A., Hildebrandt, N. & Charbonnière, L. J. (2016). Chem. Commun. 52, 5080-5095.]). At the same time, the phosphate ligand in the complexes has not displayed properties of an `antenna' ligand for luminescence sensitization (Bünzli & Piguet, 2005[Bünzli, J.-C. G. & Piguet, C. (2005). Chem. Soc. Rev. 34, 1048-1077.]; Bünzli et al., 2007[Bünzli, J.-C. G., Comby, S., Chauvin, A.-S. & Vandevyver, C. D. B. (2007). J. Rare Earths, 25, 257-274.]; Sy et al., 2016[Sy, M., Nonat, A., Hildebrandt, N. & Charbonnière, L. J. (2016). Chem. Commun. 52, 5080-5095.]; Guillou et al., 2016[Guillou, O., Daiguebonne, C., Calvez, G. & Bernot, K. (2016). Acc. Chem. Res. 49, 844-856.]; Hewitt & Butler, 2018[Hewitt, S. H. & Butler, S. J. (2018). Chem. Commun. 54, 6635-6647.]; Roitershtein et al., 2018[Roitershtein, D. M., Puntus, L. N., Vinogradov, A. A., Lyssenko, K. A., Minyaev, M. E., Dobrokhodov, M. D., Taidakov, I. V., Varaksina, E. A., Churakov, A. V. & Nifant'ev, I. E. (2018). Inorg. Chem. 57, 10199-10213.]). A 2,2′-bi­pyridine (bipy) mol­ecule can serve as such an `antenna', which usually increases the quantum yield dramatically. We have found that salt (I)[link] can be easily converted into the complex {Li2(bipy-κ2N,N′)2[(2,6-iPr2C6H3-O)2POO-μ-κO:κO′]2}(C7H8)2 (II) (Fig. 1[link]), the crystal structure of which is reported herein. It has no coordinated MeOH mol­ecule, but has the `built-in' bipy ligand. Therefore, complex (II) might be successfully utilized in the synthesis of luminescent rare-earth organophosphate complexes.

[Figure 1]
Figure 1
Synthesis of {[(2,6-iPr2C6H3O)2PO2]Li(bipy)}2(C7H8)2, (II).

On the other hand, it is known that diaryl-substituted phospho­ric acids in the presence of 3-phenyl­propan-1-ol as an initiator are capable of catalysing ring-opening polymerization (ROP) of -caprolactone (-CL) and L-lactide (LLA) into poly(-caprolactone) (PCL) and poly(L-lactide) (PLLA) at high temperatures (453 K, bulk sample; Liu et al., 2019[Liu, J., Zhang, C., Li, Z., Zhang, L., Xu, J., Wang, H., Xu, S., Guo, T., Yang, K. & Guo, K. (2019). Eur. Polym. J. 113, 197-207.]). It might be noted that ROP of -CL and LLA can also be carried out at lower temperatures: 353 K for -CL (bulk sample, the same initiator and catalysts; Saito et al., 2015[Saito, T., Aizawa, Y., Tajima, K., Isono, T. & Satoh, T. (2015). Polym. Chem. 6, 4374-4384.]) and 383 K for DL-lactide [30% of toluene by volume, glycolic acid derivatives of bio-metals (Mg, Zn, Al) were used as catalysts; Nifant'ev et al., 2018[Nifant'ev, I. E., Shlyakhtin, A. V., Bagrov, V. V., Komarov, P. D., Tavtorkin, A. N., Minyaev, M. E. & Ivchenko, P. V. (2018). Mendeleev Commun. 28, 412-414.]].

We have tested salts (I)[link] and (II) as precatalysts for -CL and LLA polymerization under two different condition sets: (1) 373 K, ∼30% of toluene by volume and (2) 453 K, bulk sample (Fig. 2[link]), using benzyl alcohol as an initiator. The monomer/precatalyst molar ratio is taken as 25:1 (with respect to one lithium phosphate unit) in order to monitor the reaction mixtures and to study the resulting short oligomers by 1H NMR spectroscopy.

[Figure 2]
Figure 2
Ring-opening polymerization of -caprolactone and L-dilactide using complexes {[(2,6-iPr2C6H3O)2PO2]Li(MeOH)3}(MeOH), (I)[link], and {[(2,6-iPr2C6H3O)2PO2]Li(bipy)}2(C7H8)2, (II).

The ROP of -CL catalysed by (I)[link] proceeds at different equivalents of an activator under mild conditions, providing PCL with a high conversion of -CL (Table 1[link], entries 1–3). The 100% conversion and a higher polymerization degree (Pn), which is a number of oligomerized monomer units, has been observed in the presence of two equivalents of PhCH2OH activator (entry 3). However, even in the absence of PhCH2OH (entry 1), the MeOH mol­ecules in complex (I)[link] act as an activator as well. According to the 1H NMR data for PCL obtained, there are two types of the RO terminal group, namely, MeO and PhCH2O. Based on NMR integral intensities, their sum corresponds to the amount of the –CH2—OH terminal group. The MeO/PhCH2O ratio decreases upon increasing the taken amount of PhCH2OH, and the corres­ponding ratio is 1.00/0.00 for entry 1, 0.73/0.27 for entry 2 and 0.58/0.42 for entry 3. Thus, compound (I)[link] does not require an additional activator because of the presence of the inter­nal one, namely, MeOH mol­ecules. Unlike for (I)[link], polymerization of -CL by (II) without an activator does not occur (entry 4). Activation by benzyl alcohol does not lead to a noticeable yield of PCL having only the PhCH2O– and –CH2—OH terminal groups (entries 5 and 6). The addition of two equivalents of the PhCH2OH activator provides higher conversions in the cases of both complexes (I)[link] and (II) (entries 3 and 6).

Table 1
Polymerization of -CL under mild conditions

Mn is the number average molar mass; Đ is the polydispersity index; Pn is the polymerization degree; Conv. is conversion of -CL into PCL and defined as [PCL]/([-CL]+[PCL]). Conditions: [-CL]/[complex]/[PhCH2OH] = 25:1 for (I) and 0.5 for (II): 0–2; toluene volume is 30%; T = 373 K, time = 3 h.

Entry Complex Equiv. of PhCH2OH Mn, ·103a Ða Pna Conv.b (%) Mn, ·103b Pnb
1 (I) 0 2.35 1.09 20 72 2.20 19
2 (I) 1 1.54 1.15 13 72 2.09 18
3 (I) 2 2.10 1.17 18 100 2.57 22
4 (II) 0 0
5 (II) 1 1.84 1.02 15 25 1.71 14
6 (II) 2 1.36 1.12 11 41 1.82 15
Notes: (a) found by size-exclusion chromatography (SEC) measurements; (b) determined by 1H NMR studies. Mn and Pn were calculated based on the end-group analysis.

Unlike -CL oligomerization, the ROP of LLA has failed under the same conditions. For example, conversion of LLA to PLLA at the [LLA]/[(II)]/[PhCH2OH] ratio of 25:0.5:2 is only 6%. Therefore, oligomerization of LLA and -CL has been studied further at a higher temperature (Table 2[link]). Conversions of -CL in the case of complex (II) (entry 2) is even higher than that for (I)[link], but the polymerization degree is higher than expected Pn = 25, which may be explained by the faster reaction rate of the catalyst with the monomer, compared to the activation rate. The ROP of LLA proceeds under these conditions, but providing a rather low conversion to PLLA and the formation of shorter oligomers than expected (entries 3 and 4).

Table 2
Bulk polymerization of ∊-CL and LLA

Conditions: [monomer]/[complex]/[PhCH2OH] = 25:1:2 for (I) and 25:0.5:2 for (II); no solvent; T = 453 K, time = 1 h.

Entry Complex Monomer Mn, ·103a Ða Pna Conv.b (%) Mn, ·103b Pnb
1 (I) -CL 0.85 1.05 7 26 0.69 6
2 (II) -CL 3.79 1.27 32 73 4.21 36
3 (I) LLA 1.79 1.12 12 62 1.55 10
4 (II) LLA 2.03 1.18 13 45 2.27 15
Notes: (a) found by SEC measurements; (b) determined by 1H NMR studies.

In summary, catalytic tests have displayed that systems based on complexes (I)[link] and (II) are capable of catalysing ROP of cyclic esters, using -caprolactone and L-dilactide as model substrates, but the catalytic activity of the systems is rather poor. Complex (I)[link] does not require an initiator for polymerization of -CL.

2. Structural commentary

The title compound (II) crystallizes in the monoclinic space group (P21/n). Its asymmetric unit (see Fig. S1 in the supporting information) contains one non-coordinating toluene mol­ecule and half the complex {Li2(bipy)2[(2,6-iPr2C6H3-O)2PO2]2}, which is located on an inversion centre (Fig. 3[link]) [symmetry code: (i) −x + 1, −y + 1, −z + 2]. The complex has an unusual Li2P2O4 core (Fig. S2 in the supporting information), in which all the O and P atoms lie in the same plane, but the Li atoms deviate from the plane by 0.338 (4) Å. According to the Cambridge Structural Database (CSD version 5.40 with updates, Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]), there are 27 crystal structures of alkali metal derivatives with (R1O)(R2O)PO2 anions (R1, R2 = alkyl, ar­yl). Only the two-dimensional coordination polymer structure of Na[O2P(O-C6H4-4-NO2)2] (CSD refcodes AGACIW/AGACIW01; Gerus & Lis, 2013[Gerus, A. & Lis, T. (2013). Acta Cryst. E69, m464-m465.]; Starynowicz & Lis, 2014[Starynowicz, P. & Lis, T. (2014). Acta Cryst. B70, 723-731.]) displays an Na2P2O4 structural motif similar to the Li2P2O4 core found in (II). On the other hand, there are a number of lithium carboxyl­ates demonstrating a very similar Li2C2O4 core with the RCO2 ligand in the same μ2-κO:κO′-bridging mode (see the CSD).

[Figure 3]
Figure 3
The mol­ecular structure of {Li2(bipy)2[(2,6-iPr2C6H3-O)2PO2]2}. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are omitted for clarity. The minor disorder component of one of the isopropyl groups is shown with open lines. Symmetry code: (i) −x + 1, −y + 1, −z + 2.

The [Li(bipy)]+ cation in (II) is nearly flat with the highest deviations from the plane being 0.102 (2) Å for N2, 0.115 (2) Å for C31 and 0.133 (2) Å for C34. To be more precise, the coordinated bipy ligand is slightly twisted about the C29—C30 bond; the dihedral angle between two planes formed by the N1/C25–C29 and N2/C30–C34 atoms is 8.41 (12)°. Selected bond distances are given in Table 3[link]. The P—OAr bond distances are longer by 0.13–0.14 Å than the other two P—O distances. The P and Li atoms adopt distorted tetra­hedral environments with the bond angles ranging from 77.49 (14)° for N1—Li1—N2 to 120.5 (2)° for O1—Li1—O2i and from 98.16 (8)° for O3—P1—O4 to 120.32 (9)° for O1—P1—O2. The smallest O—P—O angle corresponds to the OAr—P—OAr angle between the two bulky aryl ligands. These observations for the P—O distances and O—P—O bond angles are also seen for the closely related salt (I)[link] (Minyaev et al., 2015[Minyaev, M. E., Nifant'ev, I. E., Tavtorkin, A. N., Korchagina, S. A. & Zeynalova, S. S. (2015). Acta Cryst. E71, 443-446.]), for rare-earth complexes bearing the same phosphate ligand (Minyaev et al., 2017[Minyaev, M. E., Nifant'ev, I. E., Tavtorkin, A. N., Korchagina, S. A., Zeynalova, S. S., Ananyev, I. V. & Churakov, A. V. (2017). Acta Cryst. C73, 820-827.], 2018a[Minyaev, M. E., Tavtorkin, A. N., Korchagina, S. A., Bondarenko, G. N., Churakov, A. V. & Nifant'ev, I. E. (2018a). Acta Cryst. C74, 590-598.],b[Minyaev, M. E., Korchagina, S. A., Tavtorkin, A. N., Churakov, A. V. & Nifant'ev, I. E. (2018b). Acta Cryst. C74, 673-682.],c[Minyaev, M. E., Korchagina, S. A., Tavtorkin, A. N., Kostitsyna, N. N., Churakov, A. V. & Nifant'ev, I. E. (2018c). Struct. Chem. 29, 1475-1487.]) and for bis­(2,6-diiso­propyl­phen­yl)phospho­ric acid (with the exception of the P—OH bond-distance value; Gupta et al., 2018[Gupta, V., Santra, B., Mandal, D., Das, S., Narayanan, R. S., Kalita, P., Rao, D. K., Schulzke, C., Pati, S. K., Chandrasekhar, V. & Jana, A. (2018). Chem. Commun. 54, 11913-11916.]). An explan­ation for this has been given earlier (Minyaev et al., 2017[Minyaev, M. E., Nifant'ev, I. E., Tavtorkin, A. N., Korchagina, S. A., Zeynalova, S. S., Ananyev, I. V. & Churakov, A. V. (2017). Acta Cryst. C73, 820-827.]).

Table 3
Selected bond lengths (Å)

Li1—O1 1.873 (4) P1—O1 1.4795 (15)
Li1—O2i 1.911 (4) P1—O2 1.4846 (15)
Li1—N1 2.147 (4) P1—O3 1.6198 (15)
Li1—N2 2.119 (4) P1—O4 1.6132 (14)
Symmetry code: (i) -x+1, -y+1, -z+2.

3. Supra­molecular features

The extended structure of (II), for which packing plots are shown in Figs. S3–S5 of the supporting information, features weak C—H⋯O and C—H⋯π inter­actions (Table 4[link]). Any aromatic ππ stacking must be extremely weak, as the shortest centroid–centroid separation of aromatic rings is 4.1743 (13) Å.

Table 4
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of N1/C25–C29, Cg2 is the centroid of N2/C30–C34, Cg3 is the centroid of C1–C6 and Cg5 is the centroid of C35–C40.

D—H⋯A D—H H⋯A DA D—H⋯A
C28—H28⋯O3ii 0.95 2.60 3.295 (3) 130
C8—H8CCg5 0.98 2.60 3.502 (3) 152
C19—H19⋯Cg3 1.00 2.73 3.630 (2) 150
C41—H41ACg1 0.98 2.83 3.450 (4) 122
C26—H26⋯Cg2ii 0.95 2.94 3.605 (3) 128
C31—H31⋯Cg3ii 0.95 2.69 3.591 (3) 159
Symmetry code: (ii) [-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}].

4. Synthesis and crystallization

4.1. General remarks

All synthetic manipulations were performed under a purified argon atmosphere, using Schlenk glassware, dry box techniques and absolute solvents. Hexane was distilled from Na/K alloy, toluene was distilled from sodium/benzo­phenone ketyl, 2,2′-bi­pyridine was recrystallized from absolute toluene prior to use. The salt [(2,6-iPr2C6H3O)2PO2Li(MeOH)3](MeOH) was synthesized according to the literature procedure (Minyaev et al., 2015[Minyaev, M. E., Nifant'ev, I. E., Tavtorkin, A. N., Korchagina, S. A. & Zeynalova, S. S. (2015). Acta Cryst. E71, 443-446.]). (3S,6S)-3,6-Dimethyl-1,4-dioxane-2,5-dione (L-lactide, Sigma–Aldrich, 99%) was purified by double sublimation under dynamic vacuum. -Caprolactone (-CL) was distilled from CaH2 under vacuum. CDCl3 (Cambridge Isotope Laboratories, Inc., D 99.8%) was used as purchased for registering the NMR spectra of polymer samples, and was distilled from CaH2 under argon prior to recording the NMR spectra of (II). The 1H NMR spectra of polymers were recorded on a Bruker AVANCE 400 spectrometer at 297K, the 1H and 31P{1H} NMR spectra of (II) were registered on a Bruker AV-600 instrument; chemical shifts are reported in ppm relative to the solvent residual peak. Size-exclusion chromatography (SEC) analysis of polymer samples was performed at 323 K using an Agilent PL-GPC 220 gel permeation chromatograph equipped with a PLgel column, with DMF as eluents (1 ml min−1) and poly(ethyl­ene oxide) standards.

4.2. Synthesis and crystallization of (II)

A solution of 2,2′-bi­pyridine (187 mg, 1.2 mmol) in toluene (5 ml) was added dropwise to a stirred solution of (2,6-iPr2C 6H3O)2PO2Li(MeOH)4 (553 mg, 1 mmol) in toluene (20 ml). During the addition of bi­pyridine, the reaction mixture became opaque as a result of the precipitation of microcrystalline {Li2(bipy)2[(2,6-iPr2C6H3O)2PO2]2}(C7H8)2. After the addition was complete, the mixture was stirred for 1 h, and allowed to settle. The resulting solution was deca­nted. The white crystalline solid was washed with hexane (2 × 3 ml) and dried under dynamic vacuum. The yield was 84% (565 mg, 0.42 mmol) of white solid. 1H NMR (600 MHz, CDCl3): δ = 0.95 [48H, d, 3JHH =6.84Hz, –CH(CH3)2], 2.37 (6H, s, C6H5—CH3), 3.59 [8H, septet, --CH(CH3)2], 6.93–6.97 (12H, m, OiPr2C6H3), 7.17 (2H, t, Hpara in C6H5—CH3), 7.19 (4H, d, Hortho in C6H5—CH3), 7.20 (4H, dd, 3JHH = 5.25Hz and 7.27Hz, H5-bipy), 7.26 (4H, t, Hmeta in C6H5—CH3), 7.77 (4H, t, H4-bipy), 8.09 (4H, d, 3JHH = 8.00Hz, H3-bipy), 8.34 (4H, d, 3JHH = 3.76Hz, H6-bipy). 31P{1H} NMR (242.9 MHz, CDCl3): δ = 10.82. According to 1H NMR data, prolonged vacuum drying of (II) may lead to a nearly complete loss of the non-coord­inating toluene mol­ecules.

Colourless prisms of (II) were formed upon recrystallization of the obtained microcrystalline solid from a warm (∼333 K) nearly saturated solution in toluene by slow cooling to ∼268 K.

4.3. Polymerization procedures

Method 1. In a dry box, complex (I)[link] (0.1 mmol, 55 mg) or complex (II) (0.05 mmol, 67 mg), a monomer (2.5 mmol, 285 mg for -CL or 360 mg for LLA), and toluene (0.15 ml) or a solution of PhCH2OH (11 or 22 mg) in toluene (0.15 ml) were placed at room temperature (∼298 K) in a vial, which was then sealed and taken out of the box. The mixture was stirred for 3 h at 373 K. After that, a sample of the mixture was taken to register a 1H NMR spectrum to determine the monomer conversion. The remaining mixture was quenched with methanol (tenfold volume) containing 5 equiv. of acetic acid (with respect to Li phosphate), washed with methanol, dried under vacuum, taken for SEC and 1H NMR studies.

Method 2 was performed as Method 1 with the following exceptions: (1) toluene was not added, (2) the mixture was stirred for 1 h at 453 K.

The monomer conversion was determined by 1H NMR (in CDCl3) of reaction mixtures, basing on integration of the following resonance signals: CH2OC=O at 4.22 ppm for -CL and at 4.05 ppm for PCL, CH(CH3)OC=O at 5.04 ppm for LLA and at 5.15 ppm for PLLA. The end-group analysis was based on the following resonance signals of terminal-groups: 3.67 ppm for CH3—O—CO–, 5.11 ppm for Ph—CH2—O—CO–, 3.63 ppm for –CH2–CH2—OH in PCL and 4.37 ppm for –CO—CHCH3—OH in PLLA.

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 5[link]. The positions of hydrogen atoms (with the exception of the disordered fragment) were found from a difference-Fourier map but positioned geometrically (C—H distance = 0.95 Å for aromatic, 0.98 Å for methyl and 1.00 Å for methine H atoms) and refined as riding atoms with relative isotropic displacement parameters Uiso(H) = 1.5Ueq(C) for methyl H atoms and 1.2Ueq(C) otherwise. A rotating group model was applied for methyl groups. Reflection [\overline{1}]10 was affected by the beam stop and was therefore omitted from the refinement.

Table 5
Experimental details

Crystal data
Chemical formula [Li2(C24H34O4P)2(C10H8N2)2]·2C7H8
Mr 1345.47
Crystal system, space group Monoclinic, P21/n
Temperature (K) 120
a, b, c (Å) 15.2151 (9), 12.9374 (9), 19.5918 (13)
β (°) 106.935 (2)
V3) 3689.3 (4)
Z 2
Radiation type Mo Kα
μ (mm−1) 0.12
Crystal size (mm) 0.32 × 0.28 × 0.19
 
Data collection
Diffractometer Bruker APEXII CCD
Absorption correction Multi-scan (SADABS; Bruker, 2008[Bruker (2008). SMART, SAINT and SADABS. Bruker AXS, Madison, Wisconsin, USA.])
Tmin, Tmax 0.953, 0.990
No. of measured, independent and observed [I > 2σ(I)] reflections 24668, 11176, 6434
Rint 0.068
(sin θ/λ)max−1) 0.714
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.065, 0.167, 1.05
No. of reflections 11176
No. of parameters 455
No. of restraints 4
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.73, −0.73
Computer programs: APEX2 (Bruker, 2008[Bruker (2008). SMART, SAINT and SADABS. Bruker AXS, Madison, Wisconsin, USA.]), SAINT (Bruker, 2008[Bruker (2008). SMART, SAINT and SADABS. Bruker AXS, Madison, Wisconsin, USA.]), SHELXS (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2017 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. C71, 3-8.]), SHELXTL (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. A71, 3-8.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

One isopropyl group is disordered over two orientations (atoms C23A, C24A and C23B, C24B) with a corresponding disorder ratio of 0.621 (4):0.379 (4). Similarity displacement ellipsoid constraints were applied for these atoms. The C—C bond distances in the disordered isopropyl fragment were restrained to be equal within 0.002 Å.

Supporting information


Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015a); molecular graphics: SHELXTL (Sheldrick, 2015b); software used to prepare material for publication: SHELXTL (Sheldrick, 2015b) and publCIF (Westrip, 2010).

Bis[µ-bis(2,6-diisopropylphenyl) phosphato-κ2O:O']bis[(2,2'-bipyridine-κ2N,N')lithium] toluene disolvate top
Crystal data top
[Li2(C24H34O4P)2(C10H8N2)2]·2C7H8F(000) = 1440
Mr = 1345.47Dx = 1.211 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 15.2151 (9) ÅCell parameters from 1860 reflections
b = 12.9374 (9) Åθ = 2.2–22.3°
c = 19.5918 (13) ŵ = 0.12 mm1
β = 106.935 (2)°T = 120 K
V = 3689.3 (4) Å3Prism, colourless
Z = 20.32 × 0.28 × 0.19 mm
Data collection top
Bruker APEXII CCD
diffractometer
11176 independent reflections
Radiation source: fine-focus sealed tube6434 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.068
ω scansθmax = 30.5°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
h = 2119
Tmin = 0.953, Tmax = 0.990k = 1018
24668 measured reflectionsl = 2727
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.065Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.167H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0601P)2]
where P = (Fo2 + 2Fc2)/3
11176 reflections(Δ/σ)max = 0.001
455 parametersΔρmax = 0.73 e Å3
4 restraintsΔρmin = 0.73 e Å3
Special details top

Experimental. moisture sensitive

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
P10.55033 (3)0.44259 (4)0.90237 (3)0.01448 (12)
Li10.3838 (2)0.5809 (3)0.9278 (2)0.0213 (8)
O10.47626 (9)0.51925 (12)0.89620 (8)0.0205 (3)
O20.59889 (9)0.39677 (12)0.97272 (7)0.0194 (3)
O30.50419 (9)0.35531 (11)0.84357 (7)0.0151 (3)
O40.62494 (9)0.48621 (11)0.86559 (7)0.0153 (3)
C10.55407 (13)0.27551 (16)0.82381 (11)0.0152 (4)
C20.58278 (13)0.28822 (17)0.76235 (11)0.0164 (4)
C30.63163 (14)0.20661 (18)0.74391 (12)0.0208 (5)
H30.6530410.2133330.7031610.025*
C40.64958 (15)0.11659 (19)0.78325 (12)0.0236 (5)
H40.6845600.0631380.7704300.028*
C50.61646 (15)0.10444 (18)0.84148 (12)0.0228 (5)
H50.6273400.0414110.8674700.027*
C60.56727 (14)0.18322 (17)0.86273 (11)0.0177 (4)
C70.55802 (14)0.38231 (18)0.71434 (11)0.0191 (5)
H70.5214660.4304780.7353370.023*
C80.49753 (15)0.34927 (18)0.63976 (11)0.0224 (5)
H8A0.4418430.3153440.6441600.034*
H8B0.5318400.3010870.6185490.034*
H8C0.4804820.4104060.6092240.034*
C90.64346 (15)0.43998 (19)0.70861 (12)0.0245 (5)
H9A0.6806250.4612480.7562960.037*
H9B0.6246700.5012540.6784750.037*
H9C0.6797860.3943550.6873990.037*
C100.52375 (15)0.16555 (18)0.92242 (12)0.0227 (5)
H100.5079920.2344720.9387820.027*
C110.43471 (17)0.1045 (2)0.89337 (14)0.0424 (7)
H11A0.3923970.1434690.8546340.064*
H11B0.4063010.0930860.9316610.064*
H11C0.4483320.0376450.8751630.064*
C120.58768 (17)0.1106 (2)0.98601 (12)0.0346 (6)
H12A0.6445440.1504481.0037580.052*
H12B0.6020710.0416100.9715410.052*
H12C0.5577510.1041021.0238470.052*
C130.71014 (13)0.53203 (17)0.89999 (11)0.0162 (4)
C140.78864 (13)0.46933 (18)0.91914 (11)0.0184 (4)
C150.87306 (14)0.51964 (19)0.94558 (12)0.0228 (5)
H150.9278320.4797220.9586590.027*
C160.87908 (15)0.62598 (19)0.95322 (12)0.0244 (5)
H160.9373130.6583430.9711420.029*
C170.79982 (14)0.68476 (18)0.93462 (11)0.0221 (5)
H170.8042460.7576610.9404150.027*
C180.71337 (14)0.63940 (17)0.90749 (11)0.0173 (4)
C190.78642 (14)0.35270 (18)0.91193 (12)0.0209 (5)
H190.7216790.3320700.8869730.025*
C200.84666 (16)0.3149 (2)0.86683 (13)0.0292 (6)
H20A0.8279610.3492140.8202390.044*
H20B0.8395970.2399360.8601570.044*
H20C0.9110810.3311940.8911700.044*
C210.81396 (16)0.3008 (2)0.98530 (13)0.0282 (5)
H21A0.7705890.3207871.0114150.042*
H21B0.8760170.3229341.0121250.042*
H21C0.8128980.2255980.9793550.042*
C220.62759 (15)0.70588 (18)0.88586 (11)0.0223 (5)
H22B0.5758840.6621770.8645650.027*0.621 (4)
H22A0.5767240.6667580.8918250.027*0.379 (4)
C23A0.6322 (3)0.7908 (4)0.8323 (3)0.0502 (8)0.621 (4)
H23A0.6804510.8404350.8552620.075*0.621 (4)
H23B0.5729640.8264940.8164310.075*0.621 (4)
H23C0.6462980.7596490.7911220.075*0.621 (4)
C24A0.6142 (3)0.7537 (4)0.9543 (2)0.0502 (8)0.621 (4)
H24A0.5980600.6992410.9832900.075*0.621 (4)
H24B0.5647070.8050300.9414200.075*0.621 (4)
H24C0.6713140.7873080.9817350.075*0.621 (4)
C23B0.6103 (5)0.7301 (8)0.8058 (2)0.0502 (8)0.379 (4)
H23D0.5972060.6658160.7782710.075*0.379 (4)
H23E0.6650260.7628830.7986060.075*0.379 (4)
H23F0.5577890.7770870.7897440.075*0.379 (4)
C24B0.6330 (5)0.8089 (5)0.9258 (5)0.0502 (8)0.379 (4)
H24D0.6539730.7963110.9773560.075*0.379 (4)
H24E0.5720530.8411510.9130910.075*0.379 (4)
H24F0.6763360.8551090.9124960.075*0.379 (4)
N10.31930 (12)0.70375 (15)0.85729 (9)0.0211 (4)
N20.24866 (12)0.52388 (15)0.88267 (10)0.0219 (4)
C250.35823 (15)0.7887 (2)0.83969 (12)0.0256 (5)
H250.4218990.7993520.8621530.031*
C260.31201 (17)0.8618 (2)0.79114 (13)0.0289 (6)
H260.3430010.9210750.7811010.035*
C270.21972 (16)0.84689 (19)0.75752 (12)0.0265 (5)
H270.1855350.8955600.7238360.032*
C280.17841 (15)0.75913 (18)0.77422 (12)0.0224 (5)
H280.1149740.7468870.7517980.027*
C290.22933 (14)0.68876 (17)0.82367 (11)0.0176 (4)
C300.18882 (14)0.59147 (18)0.84163 (11)0.0185 (4)
C310.09483 (15)0.57103 (19)0.81733 (12)0.0244 (5)
H310.0538420.6199060.7885140.029*
C320.06218 (17)0.4787 (2)0.83577 (13)0.0306 (6)
H320.0017040.4637510.8203080.037*
C330.12327 (18)0.4085 (2)0.87683 (13)0.0321 (6)
H330.1027110.3437970.8893420.039*
C340.21567 (17)0.4349 (2)0.89937 (12)0.0281 (5)
H340.2577140.3870290.9282660.034*
C350.3720 (2)0.5927 (2)0.63362 (14)0.0377 (7)
C360.30727 (17)0.5334 (2)0.58269 (15)0.0360 (6)
H360.2559450.5044490.5941420.043*
C370.31846 (17)0.5173 (2)0.51625 (14)0.0326 (6)
H370.2747450.4773070.4819150.039*
C380.39274 (17)0.5591 (2)0.49934 (14)0.0341 (6)
H380.3997180.5479670.4532680.041*
C390.45656 (18)0.6164 (2)0.54835 (15)0.0366 (6)
H390.5081860.6441950.5367040.044*
C400.44553 (18)0.6334 (2)0.61384 (15)0.0361 (6)
H400.4895720.6743660.6472040.043*
C410.3599 (2)0.6122 (3)0.70541 (17)0.0556 (9)
H41A0.3603530.6867950.7140790.083*
H41B0.4102900.5795220.7420450.083*
H41C0.3012300.5829770.7072610.083*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
P10.0136 (2)0.0155 (3)0.0140 (3)0.0004 (2)0.0035 (2)0.0007 (2)
Li10.0173 (17)0.028 (2)0.020 (2)0.0027 (16)0.0067 (15)0.0010 (16)
O10.0170 (7)0.0212 (8)0.0247 (9)0.0034 (6)0.0081 (6)0.0004 (7)
O20.0193 (7)0.0245 (9)0.0129 (7)0.0005 (6)0.0020 (6)0.0018 (6)
O30.0130 (7)0.0152 (8)0.0156 (7)0.0001 (6)0.0020 (6)0.0017 (6)
O40.0123 (7)0.0170 (8)0.0154 (7)0.0029 (6)0.0025 (6)0.0004 (6)
C10.0111 (9)0.0150 (10)0.0181 (11)0.0008 (8)0.0018 (8)0.0030 (8)
C20.0141 (9)0.0174 (11)0.0160 (10)0.0028 (8)0.0019 (8)0.0020 (8)
C30.0184 (10)0.0250 (12)0.0188 (11)0.0013 (9)0.0050 (9)0.0010 (9)
C40.0206 (11)0.0227 (13)0.0259 (12)0.0043 (9)0.0043 (9)0.0040 (10)
C50.0245 (11)0.0157 (11)0.0239 (12)0.0008 (9)0.0003 (9)0.0022 (9)
C60.0170 (10)0.0183 (11)0.0151 (10)0.0030 (8)0.0005 (8)0.0012 (8)
C70.0190 (10)0.0215 (12)0.0166 (11)0.0001 (9)0.0050 (9)0.0013 (9)
C80.0241 (11)0.0240 (13)0.0189 (11)0.0006 (10)0.0057 (9)0.0033 (9)
C90.0265 (11)0.0269 (13)0.0207 (12)0.0052 (10)0.0078 (9)0.0024 (10)
C100.0294 (12)0.0171 (11)0.0230 (12)0.0031 (10)0.0099 (10)0.0040 (9)
C110.0343 (14)0.061 (2)0.0309 (15)0.0164 (14)0.0086 (12)0.0118 (14)
C120.0383 (14)0.0443 (17)0.0191 (13)0.0018 (13)0.0052 (11)0.0041 (11)
C130.0145 (10)0.0200 (11)0.0140 (10)0.0045 (8)0.0041 (8)0.0017 (8)
C140.0158 (10)0.0218 (12)0.0171 (11)0.0000 (9)0.0039 (8)0.0009 (9)
C150.0144 (10)0.0269 (13)0.0240 (12)0.0001 (9)0.0009 (9)0.0013 (10)
C160.0178 (10)0.0291 (14)0.0243 (12)0.0088 (10)0.0028 (9)0.0014 (10)
C170.0251 (11)0.0189 (12)0.0210 (12)0.0058 (9)0.0047 (9)0.0008 (9)
C180.0175 (10)0.0173 (11)0.0172 (11)0.0011 (8)0.0053 (8)0.0007 (8)
C190.0143 (10)0.0206 (12)0.0251 (12)0.0007 (9)0.0013 (9)0.0040 (9)
C200.0269 (12)0.0307 (14)0.0295 (14)0.0029 (11)0.0075 (10)0.0070 (11)
C210.0286 (12)0.0240 (13)0.0302 (14)0.0026 (10)0.0059 (10)0.0032 (10)
C220.0193 (11)0.0180 (12)0.0275 (13)0.0004 (9)0.0035 (9)0.0003 (9)
C23A0.0322 (15)0.048 (2)0.066 (2)0.0117 (15)0.0076 (14)0.0011 (16)
C24A0.0322 (15)0.048 (2)0.066 (2)0.0117 (15)0.0076 (14)0.0011 (16)
C23B0.0322 (15)0.048 (2)0.066 (2)0.0117 (15)0.0076 (14)0.0011 (16)
C24B0.0322 (15)0.048 (2)0.066 (2)0.0117 (15)0.0076 (14)0.0011 (16)
N10.0174 (9)0.0262 (11)0.0183 (10)0.0017 (8)0.0029 (7)0.0031 (8)
N20.0252 (10)0.0229 (10)0.0172 (10)0.0027 (8)0.0056 (8)0.0003 (8)
C250.0199 (11)0.0327 (14)0.0229 (12)0.0091 (10)0.0041 (9)0.0054 (10)
C260.0353 (13)0.0264 (14)0.0259 (13)0.0088 (11)0.0102 (11)0.0004 (10)
C270.0319 (13)0.0229 (13)0.0234 (12)0.0012 (10)0.0060 (10)0.0020 (10)
C280.0197 (11)0.0244 (13)0.0218 (12)0.0017 (9)0.0039 (9)0.0001 (9)
C290.0161 (10)0.0207 (11)0.0160 (10)0.0009 (9)0.0047 (8)0.0018 (8)
C300.0192 (10)0.0216 (12)0.0138 (10)0.0015 (9)0.0033 (8)0.0026 (8)
C310.0203 (11)0.0272 (13)0.0241 (12)0.0005 (10)0.0038 (9)0.0001 (10)
C320.0254 (12)0.0349 (15)0.0310 (14)0.0101 (11)0.0074 (10)0.0024 (11)
C330.0429 (15)0.0262 (14)0.0283 (14)0.0120 (12)0.0118 (12)0.0003 (11)
C340.0384 (14)0.0222 (13)0.0227 (12)0.0009 (11)0.0073 (10)0.0046 (10)
C350.0534 (17)0.0288 (15)0.0322 (15)0.0207 (13)0.0146 (13)0.0017 (12)
C360.0292 (13)0.0405 (17)0.0412 (16)0.0106 (12)0.0146 (12)0.0075 (13)
C370.0274 (13)0.0322 (15)0.0331 (15)0.0061 (11)0.0009 (11)0.0022 (12)
C380.0342 (14)0.0330 (15)0.0340 (15)0.0113 (12)0.0082 (11)0.0113 (12)
C390.0356 (14)0.0263 (15)0.0473 (18)0.0072 (12)0.0111 (13)0.0100 (12)
C400.0352 (14)0.0201 (13)0.0485 (18)0.0050 (11)0.0048 (13)0.0028 (12)
C410.078 (2)0.049 (2)0.049 (2)0.0113 (18)0.0318 (18)0.0008 (16)
Geometric parameters (Å, º) top
Li1—O11.873 (4)C21—H21B0.9800
Li1—O2i1.911 (4)C21—H21C0.9800
Li1—N12.147 (4)C22—C23A1.534 (3)
Li1—N22.119 (4)C22—C24B1.536 (4)
P1—O11.4795 (15)C22—C24A1.544 (3)
P1—O21.4846 (15)C22—C23B1.545 (4)
P1—O31.6198 (15)C22—H22B0.9599
P1—O41.6132 (14)C22—H22A0.9600
O3—C11.401 (2)C23A—H23A0.9800
O4—C131.406 (2)C23A—H23B0.9800
C1—C61.399 (3)C23A—H23C0.9800
C1—C21.405 (3)C24A—H24A0.9800
C2—C31.398 (3)C24A—H24B0.9800
C2—C71.517 (3)C24A—H24C0.9800
C3—C41.379 (3)C23B—H23D0.9800
C3—H30.9500C23B—H23E0.9800
C4—C51.384 (3)C23B—H23F0.9800
C4—H40.9500C24B—H24D0.9800
C5—C61.398 (3)C24B—H24E0.9800
C5—H50.9500C24B—H24F0.9800
C6—C101.520 (3)N1—C251.341 (3)
C7—C91.531 (3)N1—C291.349 (3)
C7—C81.543 (3)N2—C341.334 (3)
C7—H71.0000N2—C301.347 (3)
C8—H8A0.9800C25—C261.380 (3)
C8—H8B0.9800C25—H250.9500
C8—H8C0.9800C26—C271.380 (3)
C9—H9A0.9800C26—H260.9500
C9—H9B0.9800C27—C281.383 (3)
C9—H9C0.9800C27—H270.9500
C10—C121.516 (3)C28—C291.389 (3)
C10—C111.528 (3)C28—H280.9500
C10—H101.0000C29—C301.488 (3)
C11—H11A0.9800C30—C311.395 (3)
C11—H11B0.9800C31—C321.382 (3)
C11—H11C0.9800C31—H310.9500
C12—H12A0.9800C32—C331.379 (4)
C12—H12B0.9800C32—H320.9500
C12—H12C0.9800C33—C341.388 (3)
C13—C181.396 (3)C33—H330.9500
C13—C141.402 (3)C34—H340.9500
C14—C151.398 (3)C35—C401.390 (4)
C14—C191.515 (3)C35—C361.408 (4)
C15—C161.384 (3)C35—C411.492 (4)
C15—H150.9500C36—C371.377 (4)
C16—C171.382 (3)C36—H360.9500
C16—H160.9500C37—C381.377 (4)
C17—C181.396 (3)C37—H370.9500
C17—H170.9500C38—C391.368 (4)
C18—C221.517 (3)C38—H380.9500
C19—C201.527 (3)C39—C401.359 (4)
C19—C211.530 (3)C39—H390.9500
C19—H191.0000C40—H400.9500
C20—H20A0.9800C41—H41A0.9800
C20—H20B0.9800C41—H41B0.9800
C20—H20C0.9800C41—H41C0.9800
C21—H21A0.9800
O1—P1—O2120.32 (9)C19—C21—H21B109.5
O1—P1—O4110.33 (9)H21A—C21—H21B109.5
O2—P1—O4109.25 (8)C19—C21—H21C109.5
O1—P1—O3104.31 (8)H21A—C21—H21C109.5
O2—P1—O3112.17 (9)H21B—C21—H21C109.5
O4—P1—O398.16 (8)C18—C22—C23A112.9 (2)
O1—Li1—O2i120.5 (2)C18—C22—C24B115.8 (3)
O1—Li1—N2116.4 (2)C18—C22—C24A107.8 (2)
O2i—Li1—N2107.90 (17)C23A—C22—C24A110.5 (3)
O1—Li1—N1110.41 (18)C18—C22—C23B106.1 (3)
O2i—Li1—N1116.5 (2)C24B—C22—C23B108.0 (5)
N2—Li1—N177.49 (14)C18—C22—H22B108.5
P1—O1—Li1152.40 (16)C23A—C22—H22B108.7
P1—O2—Li1i140.35 (15)C24A—C22—H22B108.3
C1—O3—P1123.55 (12)C18—C22—H22A109.0
C13—O4—P1127.15 (12)C24B—C22—H22A108.7
C6—C1—O3118.77 (18)C23B—C22—H22A109.0
C6—C1—C2122.40 (19)C22—C23A—H23A109.5
O3—C1—C2118.64 (19)C22—C23A—H23B109.5
C3—C2—C1117.0 (2)H23A—C23A—H23B109.5
C3—C2—C7120.03 (19)C22—C23A—H23C109.5
C1—C2—C7122.83 (19)H23A—C23A—H23C109.5
C4—C3—C2121.8 (2)H23B—C23A—H23C109.5
C4—C3—H3119.1C22—C24A—H24A109.5
C2—C3—H3119.1C22—C24A—H24B109.5
C3—C4—C5119.8 (2)H24A—C24A—H24B109.5
C3—C4—H4120.1C22—C24A—H24C109.5
C5—C4—H4120.1H24A—C24A—H24C109.5
C4—C5—C6121.2 (2)H24B—C24A—H24C109.5
C4—C5—H5119.4C22—C23B—H23D109.5
C6—C5—H5119.4C22—C23B—H23E109.5
C5—C6—C1117.65 (19)H23D—C23B—H23E109.5
C5—C6—C10120.7 (2)C22—C23B—H23F109.5
C1—C6—C10121.48 (19)H23D—C23B—H23F109.5
C2—C7—C9111.94 (17)H23E—C23B—H23F109.5
C2—C7—C8109.67 (18)C22—C24B—H24D109.5
C9—C7—C8110.52 (17)C22—C24B—H24E109.5
C2—C7—H7108.2H24D—C24B—H24E109.5
C9—C7—H7108.2C22—C24B—H24F109.5
C8—C7—H7108.2H24D—C24B—H24F109.5
C7—C8—H8A109.5H24E—C24B—H24F109.5
C7—C8—H8B109.5C25—N1—C29117.0 (2)
H8A—C8—H8B109.5C25—N1—Li1128.29 (18)
C7—C8—H8C109.5C29—N1—Li1114.59 (18)
H8A—C8—H8C109.5C34—N2—C30118.0 (2)
H8B—C8—H8C109.5C34—N2—Li1125.9 (2)
C7—C9—H9A109.5C30—N2—Li1115.35 (19)
C7—C9—H9B109.5N1—C25—C26124.4 (2)
H9A—C9—H9B109.5N1—C25—H25117.8
C7—C9—H9C109.5C26—C25—H25117.8
H9A—C9—H9C109.5C25—C26—C27118.5 (2)
H9B—C9—H9C109.5C25—C26—H26120.8
C12—C10—C6112.57 (19)C27—C26—H26120.8
C12—C10—C11110.5 (2)C26—C27—C28118.1 (2)
C6—C10—C11109.20 (19)C26—C27—H27120.9
C12—C10—H10108.1C28—C27—H27120.9
C6—C10—H10108.1C27—C28—C29120.2 (2)
C11—C10—H10108.1C27—C28—H28119.9
C10—C11—H11A109.5C29—C28—H28119.9
C10—C11—H11B109.5N1—C29—C28121.8 (2)
H11A—C11—H11B109.5N1—C29—C30115.93 (19)
C10—C11—H11C109.5C28—C29—C30122.27 (19)
H11A—C11—H11C109.5N2—C30—C31121.9 (2)
H11B—C11—H11C109.5N2—C30—C29115.84 (18)
C10—C12—H12A109.5C31—C30—C29122.3 (2)
C10—C12—H12B109.5C32—C31—C30119.1 (2)
H12A—C12—H12B109.5C32—C31—H31120.5
C10—C12—H12C109.5C30—C31—H31120.5
H12A—C12—H12C109.5C33—C32—C31119.3 (2)
H12B—C12—H12C109.5C33—C32—H32120.3
C18—C13—C14123.13 (19)C31—C32—H32120.3
C18—C13—O4117.97 (18)C32—C33—C34118.1 (2)
C14—C13—O4118.63 (19)C32—C33—H33120.9
C15—C14—C13116.7 (2)C34—C33—H33120.9
C15—C14—C19119.44 (19)N2—C34—C33123.6 (2)
C13—C14—C19123.87 (18)N2—C34—H34118.2
C16—C15—C14121.8 (2)C33—C34—H34118.2
C16—C15—H15119.1C40—C35—C36117.5 (2)
C14—C15—H15119.1C40—C35—C41121.9 (3)
C17—C16—C15119.6 (2)C36—C35—C41120.5 (3)
C17—C16—H16120.2C37—C36—C35119.9 (3)
C15—C16—H16120.2C37—C36—H36120.0
C16—C17—C18121.5 (2)C35—C36—H36120.0
C16—C17—H17119.3C36—C37—C38120.3 (3)
C18—C17—H17119.3C36—C37—H37119.9
C13—C18—C17117.3 (2)C38—C37—H37119.9
C13—C18—C22122.26 (19)C39—C38—C37120.5 (3)
C17—C18—C22120.4 (2)C39—C38—H38119.7
C14—C19—C20111.86 (19)C37—C38—H38119.7
C14—C19—C21110.88 (18)C40—C39—C38119.5 (3)
C20—C19—C21110.90 (19)C40—C39—H39120.3
C14—C19—H19107.7C38—C39—H39120.3
C20—C19—H19107.7C39—C40—C35122.2 (3)
C21—C19—H19107.7C39—C40—H40118.9
C19—C20—H20A109.5C35—C40—H40118.9
C19—C20—H20B109.5C35—C41—H41A109.5
H20A—C20—H20B109.5C35—C41—H41B109.5
C19—C20—H20C109.5H41A—C41—H41B109.5
H20A—C20—H20C109.5C35—C41—H41C109.5
H20B—C20—H20C109.5H41A—C41—H41C109.5
C19—C21—H21A109.5H41B—C41—H41C109.5
O2—P1—O1—Li123.9 (4)C14—C13—C18—C22179.49 (19)
O4—P1—O1—Li1152.5 (3)O4—C13—C18—C225.5 (3)
O3—P1—O1—Li1103.0 (3)C16—C17—C18—C130.1 (3)
O2i—Li1—O1—P139.6 (5)C16—C17—C18—C22178.57 (19)
N2—Li1—O1—P194.1 (3)C15—C14—C19—C2055.2 (3)
N1—Li1—O1—P1179.9 (2)C13—C14—C19—C20124.0 (2)
O1—P1—O2—Li1i15.3 (3)C15—C14—C19—C2169.1 (3)
O4—P1—O2—Li1i113.7 (2)C13—C14—C19—C21111.6 (2)
O3—P1—O2—Li1i138.5 (2)C13—C18—C22—C23A124.4 (3)
O1—P1—O3—C1170.24 (15)C17—C18—C22—C23A54.2 (4)
O2—P1—O3—C157.97 (17)C13—C18—C22—C24B153.2 (5)
O4—P1—O3—C156.74 (16)C17—C18—C22—C24B28.2 (5)
O1—P1—O4—C1399.30 (17)C13—C18—C22—C24A113.3 (3)
O2—P1—O4—C1335.08 (19)C17—C18—C22—C24A68.1 (3)
O3—P1—O4—C13152.07 (16)C13—C18—C22—C23B87.0 (4)
P1—O3—C1—C688.2 (2)C17—C18—C22—C23B91.6 (4)
P1—O3—C1—C296.6 (2)C29—N1—C25—C261.5 (3)
C6—C1—C2—C34.5 (3)Li1—N1—C25—C26176.9 (2)
O3—C1—C2—C3179.41 (17)N1—C25—C26—C270.7 (4)
C6—C1—C2—C7171.78 (18)C25—C26—C27—C280.1 (3)
O3—C1—C2—C73.2 (3)C26—C27—C28—C290.1 (3)
C1—C2—C3—C41.2 (3)C25—N1—C29—C281.5 (3)
C7—C2—C3—C4175.14 (19)Li1—N1—C29—C28177.53 (19)
C2—C3—C4—C51.9 (3)C25—N1—C29—C30177.25 (19)
C3—C4—C5—C62.0 (3)Li1—N1—C29—C301.2 (3)
C4—C5—C6—C11.1 (3)C27—C28—C29—N10.7 (3)
C4—C5—C6—C10174.4 (2)C27—C28—C29—C30177.9 (2)
O3—C1—C6—C5179.35 (17)C34—N2—C30—C310.6 (3)
C2—C1—C6—C54.4 (3)Li1—N2—C30—C31170.00 (19)
O3—C1—C6—C103.9 (3)C34—N2—C30—C29179.11 (19)
C2—C1—C6—C10171.00 (19)Li1—N2—C30—C2910.3 (3)
C3—C2—C7—C963.0 (3)N1—C29—C30—N27.6 (3)
C1—C2—C7—C9120.9 (2)C28—C29—C30—N2171.1 (2)
C3—C2—C7—C860.0 (2)N1—C29—C30—C31172.6 (2)
C1—C2—C7—C8116.1 (2)C28—C29—C30—C318.7 (3)
C5—C6—C10—C1244.7 (3)N2—C30—C31—C320.1 (3)
C1—C6—C10—C12140.0 (2)C29—C30—C31—C32179.6 (2)
C5—C6—C10—C1178.4 (3)C30—C31—C32—C330.9 (4)
C1—C6—C10—C1196.8 (3)C31—C32—C33—C341.4 (4)
P1—O4—C13—C1892.1 (2)C30—N2—C34—C330.1 (3)
P1—O4—C13—C1493.6 (2)Li1—N2—C34—C33169.4 (2)
C18—C13—C14—C151.2 (3)C32—C33—C34—N20.9 (4)
O4—C13—C14—C15172.78 (18)C40—C35—C36—C370.2 (4)
C18—C13—C14—C19179.5 (2)C41—C35—C36—C37179.0 (3)
O4—C13—C14—C196.5 (3)C35—C36—C37—C380.0 (4)
C13—C14—C15—C160.6 (3)C36—C37—C38—C390.4 (4)
C19—C14—C15—C16180.0 (2)C37—C38—C39—C401.0 (4)
C14—C15—C16—C170.3 (3)C38—C39—C40—C351.2 (4)
C15—C16—C17—C180.6 (3)C36—C35—C40—C390.8 (4)
C14—C13—C18—C170.8 (3)C41—C35—C40—C39179.6 (3)
O4—C13—C18—C17173.17 (17)
Symmetry code: (i) x+1, y+1, z+2.
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of N1/C25–C29, Cg2 is the centroid of N2/C30–C34, Cg3 is the centroid of C1–C6 and Cg5 is the centroid of C35–C40.
D—H···AD—HH···AD···AD—H···A
C28—H28···O3ii0.952.603.295 (3)130
C8—H8C···Cg50.982.603.502 (3)152
C19—H19···Cg31.002.733.630 (2)150
C41—H41A···Cg10.982.833.450 (4)122
C26—H26···Cg2ii0.952.943.605 (3)128
C31—H31···Cg3ii0.952.693.591 (3)159
Symmetry code: (ii) x+1/2, y+1/2, z+3/2.
Polymerization of ε-CL under mild conditions top
Mn is the number average molar mass; Đ is the polydispersity index; Pn is the polymerization degree; Conv. is conversion of ε-CL into PCL and defined as [PCL]/([ε-CL]+[PCL]). Conditions: [ε-CL]/[complex]/[PhCH2OH] = 25:1 for (I) and 0.5 for (II): 0–2; toluene volume is 30%; T = 373 K, time = 3 h.
EntryComplexEquiv. of PhCH2OHMn , ·103aÐaPnaConv.b (%)Mn, ·103bPnb
1(I)02.351.0920722.2019
2(I)11.541.1513722.0918
3(I)22.101.17181002.5722
4(II)00
5(II)11.841.0215251.7114
6(II)21.361.1211411.8215
Notes: (a) found by size-exclusion chromatography (SEC) measurements; (b) determined by 1H NMR studies. Mn and Pn were calculated based on the end-group analysis.
Bulk polymerization of ε-CL and LLA top
Conditions: [monomer]/[complex]/[PhCH2OH] = 25:1:2 for (I) and 25:0.5:2 for (II); no solvent; T = 453 K, time = 1 h.
EntryComplexMonomerMn, ·103aÐaPnaConv.b (%)Mn, ·103bPnb
1(I)ε-CL0.851.057260.696
2(II)ε-CL3.791.2732734.2136
3(I)LLA1.791.1212621.5510
4(II)LLA2.031.1813452.2715
Notes: (a) found by SEC measurements; (b) determined by 1H NMR studies.
 

Acknowledgements

Equipment from the collective exploitation center "New petrochemical processes, polymer composites and adhesives" of TIPS RAS was used.

Funding information

Funding for this research was provided by: the State Program of TIPS RAS.

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