research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 71| Part 10| October 2015| Pages 1136-1139

Structure and spectroscopic properties of N,S-coordinating 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­­idene]aniline methanol monosolvate

aDepartment of Chemistry, 1250 Grand Lake Road, Cape Breton University, Sydney, Nova Scotia, B1P 6L2, Canada, and bUniversity of Alberta, X-ray Crystallography Laboratory, Department of Chemistry, Edmonton, Alberta, T6G 2G2, Canada
*Correspondence e-mail: matthias_bierenstiel@cbu.ca

Edited by R. F. Baggio, Comisión Nacional de Energía Atómica, Argentina (Received 12 August 2015; accepted 25 August 2015; online 12 September 2015)

The reaction of pyrrole-2-carboxaldehyde and 2-(methyl­sulfan­yl)aniline in refluxing methanol gave an olive-green residue in which yellow crystals of the title compound, C12H12N2S·CH3OH, were grown from slow evaporation of methanol at 263 K. In the crystal, hydrogen-bonding inter­actions link the aniline mol­ecule and a nearby methanol solvent mol­ecule. These units are linked by a pair of weak C—H⋯Omethanol interactions, forming inversion dimers consisting of two main molecules and two solvent molecules.

1. Chemical context

Compounds that contain N- and S-donor atoms have exhibited biomedical activities such as anti­bacterial properties. In addition, such N,S-compounds can be useful ligands to form transition metal complexes which we have been investigating for their use as biomimetic models for Cu enzyme models (Alberto et al., 2013[Alberto Acosta-Ramirez, J., Larade, M. C., Lloy, S. M., Cross, E. D., McLellan, B. M., Martell, J. M., McDonald, R. & Bierenstiel, M. (2013). J. Mol. Struct. 1034, 29-37.]; Cross et al., 2011[Cross, E. D., Shehzad, U., Lloy, S. M., Brown, A. R. C., Mercer, T. D., Foster, D. R., McLellan, B. L., Murray, A. R., English, M. A. & Bierenstiel, M. (2011). Synthesis, pp. 303-315.]). Recently, we have reported the synthesis and structure of xylylene-bridged bis-[ortho-amino­thio­phenols] for the design of binuclear transition metal complexes (Alberto et al., 2013[Alberto Acosta-Ramirez, J., Larade, M. C., Lloy, S. M., Cross, E. D., McLellan, B. M., Martell, J. M., McDonald, R. & Bierenstiel, M. (2013). J. Mol. Struct. 1034, 29-37.]; Cross et al., 2011[Cross, E. D., Shehzad, U., Lloy, S. M., Brown, A. R. C., Mercer, T. D., Foster, D. R., McLellan, B. L., Murray, A. R., English, M. A. & Bierenstiel, M. (2011). Synthesis, pp. 303-315.]). Copper complexes of these N2S2-ligands are studied as small biomimetic metal models for the analysis of non-blue/type-II copper enzymes such as peptidylglycine α-hy­droxy­lating monooxygenase (PHM), which is one of the two non-coupled copper ion domains of the bifunctional peptidylglycine α-amidating monooxygenase (PAM, EC 1.14.17.3) (Klinman, 2006[Klinman, J. P. (2006). J. Biol. Chem. 281, 3013-3016.]; McIntyre et al., 2009[McIntyre, N. R., Lowe, E. W. & Merkler, D. J. (2009). J. Am. Chem. Soc. 131, 10308-10319.]). Recently, we reported the X-ray structure of a trinuclear palladium(II) complex containing N,S-coordinating 2-(benzyl­sulfan­yl)anilinide and 1,3-benzo­thio­azole-2-thiol­ate ligands (Cross et al., 2014[Cross, E. D., MacDonald, K. L., McDonald, R. & Bierenstiel, M. (2014). Acta Cryst. C70, 23-27.]). The 2-amino­thio­phenol group can be used as a synthetic building motif for the preparation of benzo­thia­zolines (Chou et al., 2008[Chou, C.-H., Yu, P.-C. & Wang, B.-C. (2008). Tetrahedron Lett. 49, 4145-4146.]), thio­ethers (Ham et al., 2006[Ham, J., Cho, S. J., Ko, J., Chin, J. & Kang, H. (2006). J. Org. Chem. 71, 5781-5784.]; Schwindt et al., 1976a[Schwindt, J. D., Groegler, G. D. & Recker, K. D. (1976a). Ger. Patent DE19752509404.]) and polyurethanes (Schwindt et al., 1976b[Schwindt, J. D., Groegler, G. D. & Recker, K. D. (1976b). Ger. Patent DE19752509405.]), and has medical applications in anti­trypanosomal, anti­leishmanial and anti­malarial treatments (Parveen et al., 2005[Parveen, S., Khan, M. O. F., Austin, S. E., Croft, S. L., Yardley, V., Rock, P. & Douglas, K. T. (2005). J. Med. Chem. 48, 8087-8097.]).

[Scheme 1]

Herein, we report the X-ray structure of 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline methanol monosolvate (1) which features an aryl methyl thio­ether group and an imino-2-pyrrole motif. The imine pendant prevents the reversible formation of the benzo­thia­zoline, a transformation that was evident in the structure we reported previously that featured a free amino group and was bonded to a palladium centre (Setifi et al., 2014[Setifi, Z., Setifi, F., El Ammari, L., El-Ghozzi, M., Sopková-de Oliveira Santos, J., Merazig, H. & Glidewell, C. (2014). Acta Cryst. C70, 19-22.]). Li and co-workers first described the synthesis of (1) in 16% isolated yield (He et al., 2009[He, L.-P., Liu, J.-Y., Pan, L., Wu, J.-Q., Xu, B.-C. & Li, Y.-S. (2009). J. Polym. Sci. A Polym. Chem. 47, 713-721.]). The 1H and 13C NMR data were reported and are congruent with our data (Basuli et al., 1996[Basuli, F., Chattopadhyay, P. & Sinha, C. (1996). Polyhedron, 15, 2439-2444.]). Compound (1) was complexed with CrCl3(thf)3 (He et al., 2009[He, L.-P., Liu, J.-Y., Pan, L., Wu, J.-Q., Xu, B.-C. & Li, Y.-S. (2009). J. Polym. Sci. A Polym. Chem. 47, 713-721.]) and with VCl3(thf)3 (Mu et al., 2011[Mu, J.-S., Shi, X.-C. & Li, Y.-S. (2011). J. Polym. Sci. A Polym. Chem. 49, 2700-2708.]) as ethyl­ene polymerization catalysts (He et al., 2009[He, L.-P., Liu, J.-Y., Pan, L., Wu, J.-Q., Xu, B.-C. & Li, Y.-S. (2009). J. Polym. Sci. A Polym. Chem. 47, 713-721.]). We now provide additional compound data such as HRMS, UV–vis and FT–IR.

2. Structural commentary

Fig. 1[link] shows the mol­ecular structure of the yellow title compound. The imino group is coplanar with the pyrrole group, and the dihedral angle between the plane of the combined (pyrrol-2-yl)imino moiety and that of the benzene ring carbons is 42.71 (5)°. The imino group N1–C8 bond distance [1.2829 (17) Å] is normal. The sulfur and imino nitro­gen atoms are very nearly coplanar with the benzene ring atoms [S is 0.0595 (18) Å and N1 is 0.0620 (19) Å out of plane], while the methyl carbon C7 is 0.310 (3) Å out of the benzene ring plane.

[Figure 1]
Figure 1
Perspective view of the 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline mol­ecule showing the atom-labelling scheme. Non-hydrogen atoms are represented by Gaussian ellipsoids at the 30% probability level.

The three heteroatoms of the main mol­ecule of (1) are each involved in hydrogen-bonding inter­actions with the adjacent co-crystallized solvent methanol mol­ecule (Fig. 2[link] and Table 1[link]). The closest inter­action is between the protonated nitro­gen of the pyrrol-2-yl group and the methanol oxygen [N2⋯O1S = 2.9030 (16) Å; H2N⋯O1S = 2.025 (18) Å]. The methanol hydroxyl group shows somewhat weaker inter­actions with the imino nitro­gen [N1⋯H1SO = 2.49 (2) Å; N1⋯O1S = 3.1116 (16) Å] and the sulfur atom [S1⋯H1SO = 2.76 (3) Å; S⋯O1S = 3.5134 (12) Å].

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2N⋯O1S 0.884 (18) 2.025 (18) 2.9030 (16) 172.0 (16)
O1S—H1SO⋯S 0.83 (3) 2.76 (3) 3.5134 (12) 152 (2)
O1S—H1SO⋯N1 0.83 (3) 2.49 (2) 3.1116 (16) 132 (2)
C7—H7B⋯O1Si 0.98 2.55 3.5181 (18) 168
Symmetry code: (i) -x, -y+1, -z.
[Figure 2]
Figure 2
Illustration of hydrogen-bonded inter­actions (dotted lines) between the 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline mol­ecule and a nearby solvent methanol mol­ecule.

3. Supra­molecular features

As shown in Fig. 3[link], the methanol mol­ecules are sandwiched between the main mol­ecules of (1) in such a manner as to preclude ππ stacking inter­actions between aromatic rings of adjacent mol­ecules. The hydrogen-bonded methanol–main molecule units are linked by pairs of weakC—H⋯Omethanol inter­actions, forming inversion dimers consisting of two main molecules and two solvent molecules (Table 1[link]).

[Figure 3]
Figure 3
Packing view of (1) as viewed slightly offset from along the a axis.

In summary, 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline is a conjugated imine that exhibits three hydrogen-bonding inter­actions to methanol within the crystal packing which would make the compound effective for tridentate N,N,S metal chelation, particularly in the case where the N-hydrogen of the pyrrol-2-yl group is deproton­ated to form an anionic species.

4. Thio­ether bonding in related structures

This is the first crystallographic report of an NNS ligand system found in 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline. The closest related structure to (1) is the reported mol­ecular structure of 3-(imino-N-2-methyl­sulfanylphen­yl)imidazo[1,5-a]pyridinium-1-thiol­ate (Patra et al., 2011a[Patra, A. K., Roy, S., Javed, S. & Olmstead, M. M. (2011a). Dalton Trans. 40, 12866-12876.]), where the imine-carbon atom is α to a nitro­gen heteroatom and crystallizes in space group P[\overline{1}]. Related NNS-type ligands are published with their respective metal complexes.

A closely related compound that features a pyridyl group instead of a pyrrole has been extensively reported in metal complexes and whether the thio­ether bonds to the metal centre varies, which sheds perspective on the binding nature of compound (1). For example, the thio­ether of the pyridyl ligand does not initially bind to the metal centre of a manganese carbonyl complex unless in the presence of oxygen (Lumsden et al., 2014[Lumsden, S. E. A., Durgaprasad, G., Thomas Muthiah, K. A. & Rose, M. J. (2014). Dalton Trans. 43, 10725-10738.]). When reacted with a rhenium carbonyl complex (Jana et al., 2013[Jana, M. S., Pramanik, A. K., Kundu, S., Sarkar, D. & Mondal, T. K. (2013). Inorg. Chim. Acta, 399, 138-145.]), the thio­ether does not participate in bonding, and in contrast, the thio­ether binds to iron in its respective carbonyl complex (Mu­thiah et al., 2015[Muthiah, K. A. T., Durgaprasad, G., Xie, Z., Williams, O. M., Joseph, C., Lynch, V. M. & Rose, M. J. (2015). Eur. J. Inorg. Chem. pp. 1675-1691.]).

This variance in thio­ether bonding is also found when reacting the pyridyl ligand with various copper complexes (Addison et al., 1984[Addison, A. W., Rao, T. N. & Sinn, E. (1984). Inorg. Chem. 23, 1957-1967.]; Schnödt et al., 2011[Schnödt, J., Manzur, J., García, A., Hartenbach, I., Su, C., Fiedler, J. & Kaim, W. (2011). Eur. J. Inorg. Chem. pp. 1436-1441.]; Patra et al., 2011b[Patra, A. K., Roy, S. & Mitra, P. (2011b). Inorg. Chim. Acta, 370, 247-253.]; Chatterjee et al., 2012[Chatterjee, S. K., Roy, S., Barman, S. K., Maji, R. C., Olmstead, M. M. & Patra, A. K. (2012). Inorg. Chem. 51, 7625-7635.]; Balamurugan et al., 2006[Balamurugan, R., Palaniandavar, M., Stoeckli-Evans, H. & Neuburger, M. (2006). Inorg. Chim. Acta, 359, 1103-1113.]) where copper is our target metal centre for (1) and for our other NNS ligands. Addison and co-workers have reported a systematic study on the properties of various copper–thio­ether inter­actions (Addison et al., 1984[Addison, A. W., Rao, T. N. & Sinn, E. (1984). Inorg. Chem. 23, 1957-1967.]). In the study, they considered the presence of a nitro­gen donor in an equatorial plane to the thio­ether, strong donor solvents, and the redox chemistry of the resultant metal complexes, which would affect the displacement of the thio­ether group.

The methanol mol­ecule present in the X-ray structure of (1) does illustrate the three heteroatoms that could bond to a metal centre, though perspective can be gained from the metal complexes formed with the pyridyl ligand relative. The reported mol­ecular structures with the pyridyl metal complexes all feature distorted octa­hedral geometry. In the case of (1), the thio­ether group sits above the neighbouring benzene ring, which would contribute to the formation of a distorted octa­hedral complex and remove the direct equatorial inter­action of the sulfur to the donating nitro­gen of the imine group. In addition, the pyrrole substituent is relatively less basic than pyridine, hence deprotonation of the pyrrole ligand must occur to elicit coordination of a metal centre.

5. Synthesis and crystallization

All chemicals were purchased from commercial sources (Fisher Scientific and Sigma–Aldrich) and used without further purification. A colorless solution containing 0.683 g (7.18 mmol) of 2-pyrrole­carboxaldehyde dissolved in 15 mL of MeOH was added drop-wise to a light-green solution containing 1.00 g (7.18 mmol) of 2-(methyl­sulfan­yl)aniline in 5 mL of MeOH with stirring. After refluxing the light-green solution overnight, the solution changed color to olive green. The solution was cooled to ambient temperature, and the solvent was removed under reduced pressure. The olive-green residue was dissolved in 10 mL of MeOH, and was placed in the freezer at 263 K with a needle-punctured rubber septum. Crystals formed from the solution, and, after several days, were collected by vacuum filtration and washed with cold hexa­nes. 0.780 g (50%) of yellow crystals were isolated.

6. Spectroscopic investigations

NMR spectra were recorded on a Bruker Avance II 400 MHz spectrometer operating at 400.17 MHz for 1H and 100.6 MHz for 13C, and were referenced to tetra­methyl­silane (δ = 0 p.p.m.). High-resolution MS data were obtained using a Waters XevoG2 QToF instrument in positive electrospray ionization mode. Theoretical m/z values are reported for an abundance greater than 10% of base signal. UV-Vis spectra were recorded in quartz cuvettes on a Varian Cary 100 Bio UV–Vis spectrometer. FT–IR spectra were recorded on a Thermo Nicolet 6700 FT–IR Spectrometer as KBr pellet (approximately 1.5 mg compound in 300 mg anhydrous KBr) in the 4,000 cm−1 to 400 cm−1 range with 2 cm−1 resolution.

Spectroscopic measurements confirmed the structure of (1). High-resolution mass spectrometry gave an [M]+ ion of 217.0833 m/z, close to the calculated mass of 217.0755 m/z and the IR spectrum of (1) exhibited an imine stretch of 1611 cm−1 that is characteristic for aniline-based imines. Absorbances located at 290 nm and 300 nm in the UV spectrum are characteristic of the ππ* transition of pyrrole and C=N bonds, respectively. The ππ* transition of benzene is also present with an absorbance around 350 nm.

1H NMR (400 MHz, CDCl3) δ = 9.63 (bs, 1H), 8.22 (s, 1H), 7.22–7.14 (m, 3H), 7.03 (bs, 1H), 6.99 (d, J = 7.6 Hz, 1H), 6.71 (dd, J = 1.2, 3.6 Hz, 1H), 6.34 (t, J = 2.8 Hz, 1H), 2.47 (s, 3H) p.p.m.13C{1H} NMR (100 MHz, CDCl3) δ = 149.1, 148.9, 133.9, 131.0, 125.9, 125.2, 124.3, 123.0, 117.5, 116.4, 110.6, 14.7 p.p.m. FT–IR (KBr) 3264, 3154, 2934, 3127, 3109. 3079, 3060, 2980, 2968, 2912, 2890, 2854, 1611, 1573, 1568, 1550, 1470, 1450, 1439, 1418, 1333, 1308, 1267, 1246, 1205, 1133, 1094, 1070, 1038, 975, 970, 956, 927, 882, 864, 844, 829, 781, 746, 725, 678, 603, 586 cm−1. HRMS (ESI–TOF) m/z: [M]+ Calculated for C12H12N2S 217.0755; found 217.0833. λmax/nm (DMF, 0.022 mg mL−1) 303 (λ/dm3 mol−1cm−1 21700), 270 (19100), 208 (sh).

7. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Hydrogen atoms attached to carbons were assigned positions based on the sp2 or sp3 hybridization geometries of their attached atoms. Hydrogens attached to sp2-hybridized carbons were given isotropic displacement parameters Uiso(H) = 1.2Uiso(C) for their attached atoms, while methyl-group hydrogens were given isotropic displacement parameters Uiso(H) = 1.5Ueq(C) for their attached carbons. The coordin­ates and displacement parameters for the hydrogens attached to N2 and O1S were allowed to refine freely.

Table 2
Experimental details

Crystal data
Chemical formula C12H12N2S·CH4O
Mr 248.34
Crystal system, space group Monoclinic, P21/c
Temperature (K) 193
a, b, c (Å) 7.5959 (4), 7.0062 (4), 24.4986 (14)
β (°) 98.4543 (7)
V3) 1289.61 (12)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.24
Crystal size (mm) 0.24 × 0.20 × 0.15
 
Data collection
Diffractometer Bruker APEXII CCD
Absorption correction Integration (SADABS; Bruker, 2013[Bruker (2013). APEX2, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.935, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections 10802, 3055, 2579
Rint 0.025
(sin θ/λ)max−1) 0.663
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.090, 1.04
No. of reflections 3055
No. of parameters 165
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.28, −0.20
Computer programs: APEX2 and SAINT (Bruker, 2013[Bruker (2013). APEX2, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXD (Schneider & Sheldrick, 2002[Schneider, T. R. & Sheldrick, G. M. (2002). Acta Cryst. D58, 1772-1779.]), SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and Mercury (Macrae et al., 2006[Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453-457.]).

Supporting information


Chemical context top

Compounds that contain N- and S-donor atoms have exhibited biomedical activities such as anti­bacterial properties. In addition, such N,S-compounds can be useful ligands to form transition metal complexes which we have been investigating for their use as biomimetic models for Cu enzyme models (Alberto et al., 2013; Cross et al., 2011). Recently, we have reported the synthesis and structure of xylylene-bridged bis-[ortho-amino­thio­phenols] for the design of binuclear transition metal complexes (Alberto et al., 2013; Cross et al., 2011). Copper complexes of these N2S2-ligands are studied as small biomimetic metal models for the analysis of non-blue/type-II copper enzymes such as peptidylglycine α-hy­droxy­lating monooxygenase (PHM), which is one of the two non-coupled copper ion domains of the bifunctional peptidylglycine α-amidating monooxygenase (PAM, EC 1.14.17.3) (Klinman, 2006; McIntyre et al., 2009). Recently, we reported the X-ray structure of a trinuclear palladium(II) complex containing N,S-coordinating 2-(benzyl­sulfanyl)anilinide and 1,3-benzo­thio­azole-2-thiol­ate ligands (Cross et al., 2014). The 2-amino­thio­phenol group can be used as a synthetic building motif for the preparation of benzo­thia­zolines (Chou et al., 2008), thio­ethers (Ham et al., 2006; Schwindt et al., 1976a) and polyurethanes (Schwindt et al., 1976b), and has medical applications in anti­trypanosomal, anti­leishmanial and anti­malarial treatments (Parveen et al., 2005).

Herein, we report the X-ray structure of 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline methanol monosolvate (1) which features an aryl methyl thio­ether group and an imino-2-pyrrole motif. The imine pendant prevents the reversible formation of the benzo­thia­zoline, a transformation that was evident in the structure we reported previously that featured a free amino group and was bonded to a palladium centre (Setifi et al., 2014). Li and co-workers first described the synthesis of (1) in 16% isolated yield (He et al., 2009). The 1H and 13C NMR data were reported and are congruent with our data (Basuli et al., 1996). Compound (1) was complexed with CrCl3(thf)3 (He et al., 2009) and with VCl3(thf)3 (Mu et al., 2011) as ethyl­ene polymerization catalysts (He et al., 2009). We now provide additional compound data such as HRMS, UV–vis and FT–IR.

Structural commentary top

Fig. 1 shows the molecular structure of this yellow compound. The imino group is coplanar with the pyrrole group, and the dihedral angle between the plane of the combined (pyrrol-2-yl)imino moiety and that of the benzene ring carbons is 42.71 (5)°. The imino group N1–C8 bond distance [1.2829 (17) Å] is normal. The sulfur and imino nitro­gen atoms are very nearly coplanar with the benzene ring atoms [S is 0.0595 (18) Å and N1 is 0.0620 (19) Å out of plane], while the methyl carbon C7 is 0.310 (3) Å out of the benzene ring plane.

As shown in Fig. 2, the three heteroatoms of the main molecule of (1) are each involved in hydrogen-bonding inter­actions with the adjacent co-crystallized solvent methanol molecule. The closest inter­action is between the protonated nitro­gen of the pyrrol-2-yl group and the methanol oxygen [N2···O1S = 2.9030 (16) Å; H2N···O1S = 2.025 (18) Å]. The methanol hydroxyl group shows somewhat weaker inter­actions with the imino nitro­gen [N1···H1SO = 2.49 (2) Å; N1···O1S = 3.1116 (16) Å] and the sulfur atom [S1···H1SO = 2.76 (3) Å; S···O1S = 3.5134 (12) Å].

Supra­molecular features top

Table 1 provides information on hydrogen-bonding inter­actions and Fig. 3 illustrates the crystal packing as viewed roughly along the a axis of the unit cell. The methanol molecules are sandwiched between the main molecules of (1) in such a manner as to preclude ππ stacking inter­actions between aromatic rings of adjacent molecules. Weak inter­molecular C—H···X inter­actions are observed: C7—H7B···O1S(-x, 1 - y, -z) = 2.55 Å.

In summary, 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline is a conjugated imine that exhibits three hydrogen-bonding inter­actions to methanol within the crystal packing which would make the compound effective for tridentate N,N,S metal chelation, particularly in the case where the N-hydrogen of the pyrrol-2-yl group is deprotonated to form an anionic species.

Thio­ether bonding in related structures top

This is the first crystallographic report of an NNS ligand system found in 2-methyl­sulfanyl-N-[(1H-pyrrol-2-yl)methyl­idene]aniline. The closest related structure to (1) is the reported molecular structure of 3-(imino-N-2- methyl­sulfanyl­phenyl)­imidazo[1,5-a]pyridinium-1-thiol­ate (Patra et al., 2011a), where the imine-carbon atom is α to a nitro­gen heteroatom and crystallizes in space group P1. Related NNS-type ligands are published with their respective metal complexes.

A closely related compound that features a pyridyl group instead of a pyrrole has been extensively reported in metal complexes and whether the thio­ether bonds to the metal centre varies, which sheds perspective on the binding nature of compound (1). For example, the thio­ether of the pyridyl ligand does not initially bind to the metal centre of a manganese carbonyl complex unless in the presence of oxygen (Lumsden et al., 2014). When reacted with a rhenium carbonyl complex (Jana et al., 2013), the thio­ether does not participate in bonding, and in contrast, the thio­ether binds to iron in its respective carbonyl complex (Mu­thiah et al., 2015).

This variance in thio­ether bonding is also found when reacting the pyridyl ligand with various copper complexes (Addison et al., 1984; Schnödt et al., 2011; Patra et al., 2011b; Chatterjee et al., 2012; Balamurugan et al., 2006) where copper is our target metal centre for (1) and for our other NNS ligands. Addison and co-workers have reported a systematic study on the properties of various copper–thio­ether inter­actions (Addison et al., 1984). In the study, they considered the presence of a nitro­gen donor in an equatorial plane to the thio­ether, strong donor solvents, and the redox chemistry of the resultant metal complexes, which would affect the displacement of the thio­ether group.

The methanol molecule present in the X-ray structure of (1) does illustrate the three heteroatoms that could bond to a metal centre, though perspective can be gained from the metal complexes formed with the pyridyl ligand relative. The reported molecular structures with the pyridyl metal complexes all feature distorted o­cta­hedral geometry. In the case of (1), the thio­ether group sits above the neighbouring benzene ring, which would contribute to the formation of a distorted o­cta­hedral complex and remove the direct equatorial inter­action of the sulfur to the donating nitro­gen of the imine group. In addition, the pyrrole substituent is relatively less basic than pyridine, hence deprotonation of the pyrrole ligand must occur to elicit coordination of a metal centre.

Synthesis and crystallization top

All chemicals were purchased from commercial sources (Fisher Scientific and Sigma–Aldrich) and used without further purification. A colorless solution containing 0.683 g (7.18 mmol) of 2-pyrrole­carboxaldehyde dissolved in 15 mL of MeOH was added drop-wise to a light-green solution containing 1.00 g (7.18 mmol) of 2-(methyl­sulfanyl)aniline in 5 mL of MeOH with stirring. After refluxing the light-green solution overnight, the solution changed color to olive green. The solution was cooled to ambient temperature, and the solvent was removed under reduced pressure. The olive green residue was dissolved in 10 mL of MeOH, and was placed in the freezer at 263 K with a needle-punctured rubber septum. Crystals formed from the solution, and, after several days, were collected by vacuum filtration and washed with cold hexanes. 0.780 g (50%) of yellow crystals were isolated.

Spectroscopic investigations top

NMR spectra were recorded on a Bruker Avance II 400 MHz spectrometer operating at 400.17 MHz for 1H and 100.6 MHz for 13C, and were referenced to tetra­methyl­silane (δ = 0 p.p.m.). High-resolution MS data were obtained using a Waters XevoG2 QToF instrument in positive electrospray ionization mode. Theoretical m/z values are reported for an abundance greater than 10% of base signal. UV-Vis spectra were recorded in quartz cuvettes on a Varian Cary 100 Bio UV–Vis spectrometer. FT–IR spectra were recorded on a Thermo Nicolet 6700 FT–IR Spectrometer as KBr pellet (approximately 1.5 mg compound in 300 mg anhydrous KBr) in the 4,000 cm-1 to 400 cm-1 range with 2 cm-1 resolution.

Spectroscopic measurements confirmed the structure of (1). High-resolution mass spectrometry gave an [M]+ ion of 217.0833 m/z, close to the calculated mass of 217.0755 m/z and the IR spectrum of (1) exhibited an imine stretch of 1611 cm-1 that is characteristic for aniline-based imines. Absorbances located at 290 nm and 300 nm in the UV spectrum are characteristic of the ππ* transition of pyrrole and CN bonds, respectively. The ππ* transition of benzene is also present with an absorbance around 350 nm.

1H NMR (400 MHz, CDCl3) δ = 9.63 (bs, 1H), 8.22 (s, 1H), 7.22–7.14 (m, 3H), 7.03 (bs, 1H), 6.99 (d, J = 7.6 Hz, 1H), 6.71 (dd, J = 1.2, 3.6 Hz, 1H), 6.34 (t, J = 2.8 Hz, 1H), 2.47 (s, 3H) p.p.m.13C{1H} NMR (100 MHz, CDCl3) δ = 149.1, 148.9, 133.9, 131.0, 125.9, 125.2, 124.3, 123.0, 117.5, 116.4, 110.6, 14.7 p.p.m. FT–IR (KBr) 3264, 3154, 2934, 3127, 3109. 3079, 3060, 2980, 2968, 2912, 2890, 2854, 1611, 1573, 1568, 1550, 1470, 1450, 1439, 1418, 1333, 1308, 1267, 1246, 1205, 1133, 1094, 1070, 1038, 975, 970, 956, 927, 882, 864, 844, 829, 781, 746, 725, 678, 603, 586 cm-1. HRMS (ESI–TOF) m/z: [M]+ Calculated for C12H12N2S 217.0755; found 217.0833. λmax/nm (DMF, 0.022 mg mL-1) 303 (λ/dm3 mol-1cm-1 21700), 270 (19100), 208 (sh).

Refinement details top

Hydrogen atoms attached to carbons were assigned positions based on the sp2 or sp3 hybridization geometries of their attached atoms. Hydrogens attached to sp2-hybridized carbons were given isotropic displacement parameters 120% of those of the Ueq's for their attached atoms, while methyl-group hydrogens were given isotropic displacement parameters 150% of those for their attached carbons. The coordinates and displacement parameters for the hydrogens attached to N2 and O1S were allowed to refine freely.

Related literature top

For related literature, see: Addison et al. (1984); Alberto Acosta-Ramirez, Larade, Lloy, Cross, McLellan, Martell, McDonald & Bierenstiel (2013); Basuli et al. (1996); Chou et al. (2008); Cross et al. (2011, 2014); Ham et al. (2006); He et al. (2009); Schnödt et al. (2011); Klinman (2006); McIntyre et al. (2009); Jana et al. (2013); Mu et al. (2011); Balamurugan et al. (2006); Parveen et al. (2005); Patra et al. (2011a, 2011b) Chatterjee et al. 2012); Muthiah et al. (2014, 2015); Schwindt et al. (1976a, 1976b); Setifi et al. (2014).

Computing details top

Data collection: APEX2 (Bruker, 2013); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXD (Schneider & Sheldrick, 2002); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Perspective view of the 2-methylsulfanyl-N-[(1H-pyrrol-2-yl)methylidene]aniline molecule showing the atom-labelling scheme. Non-hydrogen atoms are represented by Gaussian ellipsoids at the 30% probability level.
[Figure 2] Fig. 2. Illustration of hydrogen-bonded interactions (dotted lines) between the2-methylsulfanyl-N-[(1H-pyrrol-2-yl)methylidene]aniline molecule and a nearby solvent methanol molecule.
[Figure 3] Fig. 3. Packing view of (1) as viewed slightly offset from along the a axis.
2-Methylsulfanyl-N-[(1H-pyrrol-2-yl)methylidene]aniline methanol monosolvate top
Crystal data top
C12H12N2S·CH4OF(000) = 528
Mr = 248.34Dx = 1.279 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 7.5959 (4) ÅCell parameters from 5994 reflections
b = 7.0062 (4) Åθ = 2.7–27.9°
c = 24.4986 (14) ŵ = 0.24 mm1
β = 98.4543 (7)°T = 193 K
V = 1289.61 (12) Å3Fragment, colourless
Z = 40.24 × 0.20 × 0.15 mm
Data collection top
Bruker APEXII CCD
diffractometer
2579 reflections with I > 2σ(I)
ω scansRint = 0.025
Absorption correction: integration
(SADABS; Bruker, 2013)
θmax = 28.1°, θmin = 1.7°
Tmin = 0.935, Tmax = 1.000h = 99
10802 measured reflectionsk = 99
3055 independent reflectionsl = 3132
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.032 w = 1/[σ2(Fo2) + (0.0414P)2 + 0.4071P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.090(Δ/σ)max < 0.001
S = 1.04Δρmax = 0.28 e Å3
3055 reflectionsΔρmin = 0.20 e Å3
165 parametersExtinction correction: SHELXL2014 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0044 (11)
Crystal data top
C12H12N2S·CH4OV = 1289.61 (12) Å3
Mr = 248.34Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.5959 (4) ŵ = 0.24 mm1
b = 7.0062 (4) ÅT = 193 K
c = 24.4986 (14) Å0.24 × 0.20 × 0.15 mm
β = 98.4543 (7)°
Data collection top
Bruker APEXII CCD
diffractometer
3055 independent reflections
Absorption correction: integration
(SADABS; Bruker, 2013)
2579 reflections with I > 2σ(I)
Tmin = 0.935, Tmax = 1.000Rint = 0.025
10802 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0320 restraints
wR(F2) = 0.090H atoms treated by a mixture of independent and constrained refinement
S = 1.04Δρmax = 0.28 e Å3
3055 reflectionsΔρmin = 0.20 e Å3
165 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S0.27868 (4)0.27649 (5)0.03023 (2)0.02884 (11)
N10.43422 (14)0.29520 (16)0.14334 (4)0.0274 (2)
N20.19082 (15)0.38459 (17)0.21958 (5)0.0308 (3)
H2N0.169 (2)0.457 (3)0.1897 (7)0.049 (5)*
C10.50824 (16)0.24857 (17)0.05218 (5)0.0242 (3)
C20.56495 (17)0.25724 (17)0.10935 (5)0.0255 (3)
C30.74554 (18)0.24302 (19)0.12952 (6)0.0309 (3)
H30.78460.25130.16810.037*
C40.86910 (17)0.2168 (2)0.09371 (6)0.0338 (3)
H40.99220.20800.10780.041*
C50.81268 (18)0.2034 (2)0.03767 (6)0.0340 (3)
H50.89720.18370.01320.041*
C60.63324 (17)0.21859 (19)0.01680 (6)0.0296 (3)
H60.59550.20850.02180.036*
C70.2639 (2)0.2898 (2)0.04355 (6)0.0345 (3)
H7A0.34190.39180.05330.052*
H7B0.14080.31710.05980.052*
H7C0.30110.16780.05780.052*
C80.44496 (18)0.21148 (19)0.19028 (5)0.0289 (3)
H80.53560.11880.19980.035*
C90.32524 (18)0.25263 (19)0.22884 (5)0.0280 (3)
C100.31947 (19)0.1746 (2)0.28029 (5)0.0330 (3)
H100.39690.07900.29770.040*
C110.1793 (2)0.2613 (2)0.30227 (6)0.0362 (3)
H110.14400.23560.33720.043*
C120.10244 (19)0.3905 (2)0.26377 (5)0.0348 (3)
H120.00390.47050.26750.042*
O1S0.15530 (14)0.62192 (16)0.12144 (4)0.0388 (3)
H1SO0.221 (3)0.551 (4)0.1064 (10)0.090 (8)*
C1S0.2439 (2)0.7991 (2)0.12954 (7)0.0493 (4)
H1SA0.20390.86590.16070.074*
H1SB0.21670.87680.09610.074*
H1SC0.37260.77750.13750.074*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S0.02473 (17)0.0349 (2)0.02682 (18)0.00058 (12)0.00369 (12)0.00038 (13)
N10.0292 (5)0.0298 (6)0.0235 (5)0.0037 (4)0.0048 (4)0.0030 (4)
N20.0348 (6)0.0332 (6)0.0238 (5)0.0001 (5)0.0020 (4)0.0037 (5)
C10.0252 (6)0.0213 (6)0.0265 (6)0.0033 (4)0.0054 (5)0.0004 (5)
C20.0274 (6)0.0223 (6)0.0274 (6)0.0025 (5)0.0055 (5)0.0006 (5)
C30.0304 (6)0.0302 (7)0.0310 (7)0.0018 (5)0.0007 (5)0.0017 (5)
C40.0236 (6)0.0322 (7)0.0452 (8)0.0007 (5)0.0035 (5)0.0003 (6)
C50.0292 (6)0.0333 (8)0.0421 (8)0.0020 (5)0.0135 (6)0.0056 (6)
C60.0304 (6)0.0305 (7)0.0294 (7)0.0040 (5)0.0089 (5)0.0042 (5)
C70.0400 (7)0.0345 (8)0.0273 (7)0.0033 (6)0.0006 (5)0.0031 (5)
C80.0309 (6)0.0283 (7)0.0274 (6)0.0039 (5)0.0043 (5)0.0017 (5)
C90.0313 (6)0.0276 (7)0.0246 (6)0.0035 (5)0.0028 (5)0.0002 (5)
C100.0367 (7)0.0346 (7)0.0271 (7)0.0008 (6)0.0029 (5)0.0058 (5)
C110.0413 (8)0.0446 (8)0.0234 (6)0.0034 (6)0.0072 (5)0.0013 (6)
C120.0346 (7)0.0392 (8)0.0312 (7)0.0007 (6)0.0068 (5)0.0027 (6)
O1S0.0424 (6)0.0343 (6)0.0414 (6)0.0066 (5)0.0124 (5)0.0013 (5)
C1S0.0525 (9)0.0449 (10)0.0524 (10)0.0038 (8)0.0144 (8)0.0030 (8)
Geometric parameters (Å, º) top
S—C11.7586 (13)C7—H7A0.9800
S—C71.7968 (14)C7—H7B0.9800
N1—C81.2829 (17)C7—H7C0.9800
N1—C21.4118 (16)C8—C91.4334 (18)
N2—C121.3557 (17)C8—H80.9500
N2—C91.3714 (17)C9—C101.3806 (18)
N2—H2N0.884 (18)C10—C111.401 (2)
C1—C61.3924 (17)C10—H100.9500
C1—C21.4049 (18)C11—C121.374 (2)
C2—C31.3915 (18)C11—H110.9500
C3—C41.388 (2)C12—H120.9500
C3—H30.9500O1S—C1S1.412 (2)
C4—C51.380 (2)O1S—H1SO0.83 (3)
C4—H40.9500C1S—H1SA0.9800
C5—C61.3878 (19)C1S—H1SB0.9800
C5—H50.9500C1S—H1SC0.9800
C6—H60.9500
C1—S—C7103.05 (7)S—C7—H7C109.5
C8—N1—C2119.01 (12)H7A—C7—H7C109.5
C12—N2—C9109.42 (11)H7B—C7—H7C109.5
C12—N2—H2N126.0 (11)N1—C8—C9122.40 (13)
C9—N2—H2N124.6 (11)N1—C8—H8118.8
C6—C1—C2119.34 (12)C9—C8—H8118.8
C6—C1—S124.24 (10)N2—C9—C10107.17 (12)
C2—C1—S116.42 (9)N2—C9—C8123.75 (12)
C3—C2—C1119.51 (12)C10—C9—C8129.07 (13)
C3—C2—N1123.11 (12)C9—C10—C11107.89 (13)
C1—C2—N1117.19 (11)C9—C10—H10126.1
C4—C3—C2120.54 (13)C11—C10—H10126.1
C4—C3—H3119.7C12—C11—C10106.98 (12)
C2—C3—H3119.7C12—C11—H11126.5
C5—C4—C3119.86 (13)C10—C11—H11126.5
C5—C4—H4120.1N2—C12—C11108.53 (13)
C3—C4—H4120.1N2—C12—H12125.7
C4—C5—C6120.39 (13)C11—C12—H12125.7
C4—C5—H5119.8C1S—O1S—H1SO106.4 (18)
C6—C5—H5119.8O1S—C1S—H1SA109.5
C5—C6—C1120.32 (13)O1S—C1S—H1SB109.5
C5—C6—H6119.8H1SA—C1S—H1SB109.5
C1—C6—H6119.8O1S—C1S—H1SC109.5
S—C7—H7A109.5H1SA—C1S—H1SC109.5
S—C7—H7B109.5H1SB—C1S—H1SC109.5
H7A—C7—H7B109.5
C7—S—C1—C67.76 (13)C2—C1—C6—C52.00 (19)
C7—S—C1—C2172.43 (10)S—C1—C6—C5178.18 (10)
C6—C1—C2—C32.43 (18)C2—N1—C8—C9175.38 (11)
S—C1—C2—C3177.75 (10)C12—N2—C9—C100.08 (15)
C6—C1—C2—N1177.62 (11)C12—N2—C9—C8179.73 (13)
S—C1—C2—N12.55 (15)N1—C8—C9—N20.6 (2)
C8—N1—C2—C341.88 (18)N1—C8—C9—C10179.65 (14)
C8—N1—C2—C1143.11 (12)N2—C9—C10—C110.04 (16)
C1—C2—C3—C41.2 (2)C8—C9—C10—C11179.75 (13)
N1—C2—C3—C4176.13 (12)C9—C10—C11—C120.01 (16)
C2—C3—C4—C50.4 (2)C9—N2—C12—C110.08 (16)
C3—C4—C5—C60.9 (2)C10—C11—C12—N20.06 (17)
C4—C5—C6—C10.4 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2N···O1S0.884 (18)2.025 (18)2.9030 (16)172.0 (16)
O1S—H1SO···S0.83 (3)2.76 (3)3.5134 (12)152 (2)
O1S—H1SO···N10.83 (3)2.49 (2)3.1116 (16)132 (2)
C7—H7B···O1Si0.982.553.5181 (18)168
Symmetry code: (i) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2N···O1S0.884 (18)2.025 (18)2.9030 (16)172.0 (16)
O1S—H1SO···S0.83 (3)2.76 (3)3.5134 (12)152 (2)
O1S—H1SO···N10.83 (3)2.49 (2)3.1116 (16)132 (2)
C7—H7B···O1Si0.982.553.5181 (18)167.9
Symmetry code: (i) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC12H12N2S·CH4O
Mr248.34
Crystal system, space groupMonoclinic, P21/c
Temperature (K)193
a, b, c (Å)7.5959 (4), 7.0062 (4), 24.4986 (14)
β (°) 98.4543 (7)
V3)1289.61 (12)
Z4
Radiation typeMo Kα
µ (mm1)0.24
Crystal size (mm)0.24 × 0.20 × 0.15
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionIntegration
(SADABS; Bruker, 2013)
Tmin, Tmax0.935, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
10802, 3055, 2579
Rint0.025
(sin θ/λ)max1)0.663
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.090, 1.04
No. of reflections3055
No. of parameters165
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.28, 0.20

Computer programs: APEX2 (Bruker, 2013), SAINT (Bruker, 2013), SHELXD (Schneider & Sheldrick, 2002), SHELXL2014 (Sheldrick, 2015), SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006), SHELXTL (Sheldrick, 2008).

 

Acknowledgements

The authors thank NSERC and Cape Breton University for financial support of this research. We also thank M. C. Larade for assistance with data file compilation.

References

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Volume 71| Part 10| October 2015| Pages 1136-1139
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