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metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296
Volume 61| Part 12| December 2005| Pages m497-m500
doi:10.1107/S0108270105033913

Bis[(2-pyrid­yl)(2-pyridyl­amino)­methanol­ato]cobalt(III) perchlorate: a consequence of cobalt ion-assisted oxidative deamination of a tris­­(pyrid­yl)aminal ligand

CROSSMARK_Color_square_no_text.svg
Harry Adams,a* Musa S. Shongwe,b Ibtisam Al-Bahri,b Eiman Al-Busaidib and Michael J. Morrisa

aDepartment of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, England, and bDepartment of Chemistry, College of Science, Sultan Qaboos University, PO Box 36, Al-Khod 123, Muscat, Oman
*Correspondence e-mail: h.adams@sheffield.ac.uk

(Received 14 September 2005; accepted 19 October 2005; online 11 November 2005)

The title compound, [Co(C11H10N3O)2]ClO4, designated [Co(L2)2]ClO4, was synthesized by reaction of CoII with two molar equivalents of (2-pyrid­yl)­bis­(2-pyridylamino)­methane (L1) under ambient conditions, whereby the divalent metal ion was oxidized concomitantly with oxygenation and deamination of the aminal polydentate ligand to generate the tridentate ligand anion (2-pyrid­yl)(2-pyridyl­amino)­methanol­ate, L2−. In the X-ray crystal structure of the complex cation, [Co(L2)2]+, the two L2− ligands are coordinated to the central cobalt(III) metal ion in a facial mode to afford a pseudo-octa­hedral geometry. The four pyridyl N atoms constitute the equatorial plane on which the cobalt(III) ion lies; the methanol­ate O atoms occupy the axial positions.

Comment

One of the crucial requirements for a metal to act as an electron carrier at biochemical redox centres is the availability of at least two readily accessible stable oxidation states of the metal that differ by one unit. Hence, several of the first-row transition metals play major roles in a diverse range of enzymatic and electron-transfer processes in biological systems. Cobalt is well known for its role in the inorganic biochemistry of the cobalamins, rare examples of naturally occurring organometallic compounds (Cotton et al., 1999[Cotton, F. A., Wilkinson, G., Murillo, C. A. & Bochmann, M. (1999). Advanced Inorganic Chemistry, 6th ed., pp. 814-835. New York: John Wiley & Sons.]). At the centre of the coenzymes of the cobalamins, namely 5′-deoxy­adenosylcobalamin (coenzyme B12) and methyl­cobalamin (MeB12), cobalt participates in catalytic radical-induced 1,2-rearrangement reactions and bio­methyl­ations, respectively (Lippard & Berg, 1994[Lippard, S. J. & Berg, J. M. (1994). Principles of Inorganic Chemistry, pp. 336-343. Mill Valley: University Science Books.]; Bertini & Luchinat, 1994[Bertini, I. & Luchinat, C. (1994). Bioinorganic Chemistry, edited by I. Bertini, H. B. Gray, S. J. Lippard & J. S. Valentine, pp. 97-101. Sausalito: University Science Books.]; Kaim & Schwederski, 1994[Kaim, W. & Schwederski, B. (1994). Bioinorganic Chemistry: Inorganic Elements in the Chemistry of Life, pp. 39-55, 112-118. Chichester: John Wiley & Sons.]). In the catalytic cycles of these processes, cobalt shuttles between the divalent and trivalent states, and in MeB12, the relatively uncommon +1 state is also utilized (Drennan et al., 1994[Drennan, C. L., Huang, S., Drummond, J. T., Matthews, R. G. & Ludwig, M. L. (1994). Science, 266, 1669-1674.]; Kräutler & Kratky, 1996[Kräutler, B. & Kratky, C. (1996). Angew. Chem. Int. Ed. Engl. 35, 167-170.]).

The importance of low-spin cobalt(III) revolves around the kinetic inertness of its compounds, which has facilitated mechanistic studies in coordination chemistry. Virtually all octa­hedral cobalt(III) complexes are diamagnetic (configuration t2g6), with the exception of [CoF6]3− and [CoF3(H2O)3] (Cotton et al., 1999[Cotton, F. A., Wilkinson, G., Murillo, C. A. & Bochmann, M. (1999). Advanced Inorganic Chemistry, 6th ed., pp. 814-835. New York: John Wiley & Sons.]). Generally, in coordination chemistry, CoIII is obtained from CoII by atmospheric or chemical oxidation (using oxidants such as H2O2). The title compound, (I)[link], was synthesized by reaction of Co(ClO4)2·6H2O with two molar equivalents of (2-pyrid­yl)­bis­(2-pyridylamino)methane (L1) (Galvez et al., 1986[Galvez, E., Lorente, A., Iriepa, I., Florencio, F. & García-Blanco, S. (1986). J. Mol. Struct. 142, 447-450.]; Arulsamy & Hodgson, 1994[Arulsamy, N. & Hodgson, D. J. (1994). Inorg. Chem. 33, 4531-4536.]) in EtOH in the presence of mol­ecular oxygen at room temperature (see scheme[link] below). Compound (I)[link] was also obtained from the template reaction of stoichiometric amounts of pyridine-2-carbaldehyde, 2-amino­pyridine and Co(ClO4)2·6H2O in re­fluxing ethanol. Microanalyses (C, H and N) of a crystalline sample of (I) are consistent with the suggested chemical formulation of (I). The IR spectrum of this compound exhibits a sharp absorption at 3356 cm−1, confirming the presence of NH (secondary amine) in the L2− ligand synthesized in situ. The aliphatic and aromatic ν(C—H) absorptions occur at 2875 and 3080 cm−1, respectively. The pyridyl ring vibrations are indicated by the stretching frequencies in the range 1400–1620 cm−1. The uncoordinated perchlorate ion is characterized by an intense and broad absorption centred around 1090 cm−1 and a moderate and sharp band at 625 cm−1 (Nakamoto, 1997[Nakamoto, K. (1997). Infrared and Raman Spectra of Inorganic and Coordination Compounds, 5th ed., pp. 82-83. New York: John Wiley & Sons.]; Srinivasan et al., 2005[Srinivasan, S., Annaraj, J. & Athappan, P. R. (2005). J. Inorg. Biochem. 99, 876-882.]).

[Scheme 1]

As observed previously for other octa­hedral CoIII complexes with S = 0 (e.g. Mak et al., 1991[Mak, S.-T., Wong, W.-T., Yam, V. W.-W., Lai, T.-F. & Che, C.-M. (1991). J. Chem. Soc. Dalton Trans. pp. 1915-1922.]; Emseis et al., 2004[Emseis, P., Failes, T. W., Hibbs, D. E., Leverett, P. & Williams, P. A. (2004). Polyhedron, 23, 1749-1767.]), the 1H NMR spectrum of [Co(L2)2]ClO4 in DMSO-d6 exhibits sharp resonances, showing that (I) is indeed diamagnetic. A signal corresponding to the secondary amine H atom is observed at 5.52 p.p.m., and several multiplets in the chemical shift range 6.22–8.85 p.p.m. are associated with the pyridyl H atoms. Further evidence for the singlet ground state of compound (I)[link] is provided by UV–visible spectroscopy. The electronic spectrum of (I)[link] (Fig. 1[link]) displays a shoulder at 398 nm [partially obscured by an intense intra­ligand π→π* band at 315 nm (∊ = 19500 M−1 cm−1)] and a weak band at 514 nm (∊ = 80 M−1 cm−1), typical of low-spin CoIII complexes. Owing to the common chromophore CoIIIN4O2, regardless of the differences in the other moieties present, the related CoIII compounds carbonatobis­[2-(2-pyridylamino)-5,6-dihydro-4H-1,3-thia­zine]cobalt(III) chloride (Barros-García et al., 2004[Barros-García, F. J., Bernalte-García, A., Higes-Rolando, F. J., Luna-Giles, F. & Pedrero-Marín, R. (2004). Polyhedron, 23, 1453-1460.]), (4,11-diacetato-1,4,8,11-tetra­azabicyclo[6.6.2]hexa­decane)­cobalt(III) hexa­fluoro­phosphate (Lichty et al., 2004[Lichty, J., Allen, S. M., Grillo, A. I., Archibald, S. J. & Hubin, T. J. (2004). Inorg. Chim. Acta, 357, 615-618.]) and trans-bis­(1,3-diamino-2-propanolato)-cobalt(III) perchlorate (Bruce, 2003[Bruce, D. A. (2003). J. Chem. Crystallogr. 33, 569-574.]) have electronic spectra that resemble that of compound (I), with two cobalt-based absorptions in each case at 395 (shoulder) and 532 nm, 355 and 494 nm, and 394 and 498 nm, respectively. For all these aforementioned compounds, including (I)[link], the two absorptions are attributable to ligand–field transitions; the higher-energy absorption represents the 1A1g→1T2g transition, whereas the other is ascribed to the 1A1g→1T1g transition. Commonly, the higher-energy d–d band is masked by intra­ligand π→π* or LMCT bands (Djebbar-Sid et al., 2001[Djebbar-Sid, S., Benali-Baitich, O. & Deloume J. P. (2001). J. Mol. Struct. 569, 121-128.]; Tiliakos et al., 2001[Tiliakos, M., Cordopatis, P., Terzis, A., Raptopoulou, C. P., Perlepes, S. P. & Manessi-Zoupa, E. (2001). Polyhedron, 20, 2203-2214.]; Shongwe, Al-Hatmi et al., 2002[Shongwe, M. S., Al-Hatmi, S. K. M., Marques, H. M., Smith, R., Nukada, R. & Mikuriya, M. (2002). J. Chem. Soc. Dalton Trans. pp. 4064-4069.]; Saha et al., 2003[Saha, N. C., Butcher, R. J., Chaudhuri, S. & Saha, N. (2003). Polyhedron, 22, 383-390.]; Barros-García et al., 2004[Barros-García, F. J., Bernalte-García, A., Higes-Rolando, F. J., Luna-Giles, F. & Pedrero-Marín, R. (2004). Polyhedron, 23, 1453-1460.]). The pink–red colour of (I) is consistent with the electronic absorptions (Fig. 1[link]).

Definitive evidence for the cobalt ion-assisted transformation of (2-pyrid­yl)bis(2-pyridylamino)methane (L1) to (2-pyridyl)bis­(2-pyridylamino)methanol­ate (L2−) in situ was provided by single-crystal X-ray crystallography. Compound (I)[link] was isolated at room temperature as pink–red block-shaped crystals; it crystallized in the ortho­rhom­bic space group Pca21. The crystal structure of (I) comprises a complex cation, [Co(L2)2]+, and a disordered perchlorate counter-anion (Fig. 2[link]). The arrangement of the discrete mononuclear complex cations and counter-ions is shown in Fig. 3[link]. Selected bond distances and angles are given in Table 1[link]. The crystal structure of the complex cation shows two tridentate (2-pyrid­yl)­bis­(2-pyridylamino)methanol­ate ligands coordinated facially to the cobalt(III) ion to form a distorted octa­hedral geometry. The distortion, evidenced by deviations from idealized Oh angles of 90° and differences in bond distances in the coordination sphere, is a consequence of ligand constraints. The cobalt(III) ion resides on a pseudo-twofold axis of symmetry and on an equatorial plane formed by the pyridyl N atoms of the two ligands. The methanol­ate O atoms, in the axial positions [O1—Co1—O2 = 172.61 (19)°], have stronger inter­actions with the central metal atom [CoIII—Omethanolate = 1.893 (4) and 1.894 (4) Å] than do the pyridyl N atoms (Table 1[link]). The CoIII—Omethanolate distances compare favourably with the CoIII—Opropanolate [1.867 (6) and 1.921 (5) Å; Bruce, 2003[Bruce, D. A. (2003). J. Chem. Crystallogr. 33, 569-574.]], CoIII—Ocarboxylate [1.882 (6) and 1.916 (3) Å; Shongwe, Al-Juma & Fernandes, 2002[Shongwe, M. S., Al-Juma, S. A. & Fernandes, M. A. (2002). Acta Cryst. E58, m457-m459.]; Lichty et al., 2004[Lichty, J., Allen, S. M., Grillo, A. I., Archibald, S. J. & Hubin, T. J. (2004). Inorg. Chim. Acta, 357, 615-618.]], CoIII—Onaphtholate [1.886 (4)–1.9139 (17) Å; Kurahashi, 1976[Kurahashi, M. (1976). Bull. Chem. Soc. Jpn, 49, 3053-3059.]; Shongwe, Al-Juma & Fernandes, 2002[Shongwe, M. S., Al-Juma, S. A. & Fernandes, M. A. (2002). Acta Cryst. E58, m457-m459.]], CoIII—Ophenolate [1.862 (6)–1.928 (2) Å; Nassimbeni et al., 1976[Nassimbeni, L. R., Percy, G. C. & Rodgers, A. L. (1976). Acta Cryst. B32, 1252-1256.]; Chen et al., 1991[Chen, M.-Q., Xu, J.-X. & Zhang, H.-L. (1991). Xiegou Huaxue (J. Struct. Chem.), 10, 1-9.]; Shongwe, Al-Hatmi et al., 2002[Shongwe, M. S., Al-Hatmi, S. K. M., Marques, H. M., Smith, R., Nukada, R. & Mikuriya, M. (2002). J. Chem. Soc. Dalton Trans. pp. 4064-4069.]] and CoIII—Ocarbonate distances [1.907 (2) and 1.919 (2) Å; Barros-García et al., 2004[Barros-García, F. J., Bernalte-García, A., Higes-Rolando, F. J., Luna-Giles, F. & Pedrero-Marín, R. (2004). Polyhedron, 23, 1453-1460.]]. Likewise, the CoIII—Npyridyl distances of (I) [1.917 (4)–1.962 (4) Å] are normal (Tiliakos et al., 2001[Tiliakos, M., Cordopatis, P., Terzis, A., Raptopoulou, C. P., Perlepes, S. P. & Manessi-Zoupa, E. (2001). Polyhedron, 20, 2203-2214.]; Ghiladi et al., 2003[Ghiladi, M., Gomez, J. T., Hazell, A., Kofod, P., Lumtscher, J. & McKenzie, C. J. (2003). Dalton Trans. pp. 1320-1325.]; Barros-García et al., 2004[Barros-García, F. J., Bernalte-García, A., Higes-Rolando, F. J., Luna-Giles, F. & Pedrero-Marín, R. (2004). Polyhedron, 23, 1453-1460.]; Stamatatos et al., 2005[Stamatatos, T. C., Bell, A., Cooper, P., Terzis, A., Raptopoulou, C. P., Heath, S. L., Winpenny, R. E. P. & Perlepes, S. P. (2005). Inorg. Chem. Commun. 8, 533-538.]). Owing to steric constraints, the two CoIII—Npyridyl distances (for each L2− ligand) in (I)[link] are significantly different (by 0.044 Å). Similar behaviour has been demonstrated by the CoIII complex of deprotonated N,N′-bis­(2-pyrid­yl)urea (Tiliakos et al., 2001[Tiliakos, M., Cordopatis, P., Terzis, A., Raptopoulou, C. P., Perlepes, S. P. & Manessi-Zoupa, E. (2001). Polyhedron, 20, 2203-2214.]).

The metal ion-assisted conversion of L1 to L2− has been demonstrated previously (Arulsamy & Hodgson, 1994[Arulsamy, N. & Hodgson, D. J. (1994). Inorg. Chem. 33, 4531-4536.]) using manganese(II) and iron(II) to form the MIII complexes [Mn(L2)2]ClO4 and [Fe(L2)2]ClO4, respectively, which are chemically isostructural with (I)[link]. It is noteworthy that in the case of the high-spin (t2g3eg1) MnIII analogue, the equatorial bonds (Mn—Npyridyl) appear elongated in accordance with the Jahn–Teller effect (evident axial compression). In the reaction of MII (M = Mn, Fe or Co) with L1 in air, oxygen is inserted into the ligand at the aliphatic C atom, causing deamination, as shown in the scheme[link]. Cytochrome P450-dependent incorporation of O atoms from freely available mol­ecular oxygen into organic chemical substrates occurs extensively in nature (Kaim & Schwederski, 1994[Kaim, W. & Schwederski, B. (1994). Bioinorganic Chemistry: Inorganic Elements in the Chemistry of Life, pp. 39-55, 112-118. Chichester: John Wiley & Sons.]). In our system, we and others (Arulsamy & Hodgson, 1994[Arulsamy, N. & Hodgson, D. J. (1994). Inorg. Chem. 33, 4531-4536.]) have shown that a crucial requirement for the oxidative degradation of the aminal ligand L1 is accessibility of a stable MIII oxidation state. Oxygenation of the ligand occurs in conjunction with oxidation of the MII ions. In the case of Ni2+ (Arulsamy & Hodgson, 1994[Arulsamy, N. & Hodgson, D. J. (1994). Inorg. Chem. 33, 4531-4536.]) and Cu2+, the ligand L1 remains intact during the reaction.

[Figure 1]
Figure 1
The electronic absorption spectrum of (I) in dimethyl sulfoxide (DMSO): 0.10 mM (lower line) and 3.0 mM (higher line).
[Figure 2]
Figure 2
The crystal structure of (I), showing the mononuclear complex cation and the disordered perchlorate counter-ion.
[Figure 3]
Figure 3
The packing of (I).

Experimental

L1 was synthesized following literature procedures (Galvez et al., 1986[Galvez, E., Lorente, A., Iriepa, I., Florencio, F. & García-Blanco, S. (1986). J. Mol. Struct. 142, 447-450.]; Arulsamy & Hodgson, 1994[Arulsamy, N. & Hodgson, D. J. (1994). Inorg. Chem. 33, 4531-4536.]). A solution of 2-amino­pyridine (4.7152 g, 0.050 mol) in ethanol (20 ml) was mixed with a solution of pyridine-2-carbaldehyde (2.6780 g, 0.025 mol) in ethanol (20 ml) to give a light-yellow–brown solution. This solution was heated under reflux for 10 h, during which time its colour remained essentially the same. Slow evaporation of the solution at room temperature over a period of 5 d gave colourless block-shaped crystals, which were washed several times with ice-cold ethanol and dried in air (yield 6.1012 g, 88.0%; m.p. 389–391 K). Microanalysis found: C 69.40, H 5.47, N 25.15%; calculated for C16H15N5 (Mr = 277.328): C 69.30, H 5.45, N 25.25%; IR (KBr, cm−1): 3290, 3245 (N—H); UV–vis (DMSO, nm): 260 (∊ = 15500 M−1 cm−1), 300 (∊ = 9540 M−1 cm−1). For the preparation of (I)[link], Co(ClO4)2·6H2O (0.1464 g, 0.40 mmol) was added to a solution of L1 (0.2219 g, 0.80 mmol) in ethanol (20 ml); an orange solution formed immediately and progressively darkened over time with continuous stirring at room temperature. After 5 min of stirring, the pink–red solution was filtered and kept at room temperature. After three days of slow evaporation, bright pink–red block-shaped crystals were deposited. After one week, the crystals had grown larger and become dark red. The crystals were washed with ice-cold ethanol and dried in air (yield 0.1375 g, 61.5%). [Co(L2)2]ClO4 was also obtained in higher yield (75%) from the template reaction of stoichiometric amounts (0.20 mmol scale based on the CoII salt) of 2-amino­pyridine, pyridine-2-­carbaldehyde and Co(ClO4)2·6H2O (m.p. 514–515 K). Microanalysis found: C 47.20, H 3.62, N 14.94%; calculated for C22H20ClCoN6O6 (Mr = 558.82): C 47.29, H 3.61, N 15.04%; IR (KBr, cm−1): 3356 (N—H), 1090, 625 (ClO4−); UV–vis (DMSO, nm): 263 (∊ = 19500 M−1 cm−1), 315 (∊ = 7800 M−1 cm−1), 398 (shoulder), 514 (∊ = 80 M−1 cm−1); 1H NMR (DMSO-d6, p.p.m.): δ 5.52 (d), 6.22–8.85 (m).

Crystal data

  • [Co(C11H10N3O)2]ClO4

  • Mr = 558.82

  • Orthorhombic, P c a 21

  • a = 14.802 (3) Å

  • b = 8.6144 (18) Å

  • c = 17.832 (4) Å

  • V = 2273.8 (8) Å3

  • Z = 4

  • Dx = 1.632 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 1903 reflections

  • θ = 2.3–27.6°

  • μ = 0.93 mm−1

  • T = 150 (2) K

  • Block, red

  • 0.32 × 0.12 × 0.12 mm
Data collection

  • Bruker SMART 1000 diffractometer

  • ω scans

  • Absorption correction: multi-scan(SADABS; Bruker, 1997[Bruker (1997). SMART, SAINT, SHELXTL and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])Tmin = 0.756, Tmax = 0.897

  • 23722 measured reflections

  • 5164 independent reflections

  • 4598 reflections with I > 2σ(I)

  • Rint = 0.065

  • θmax = 27.6°

  • h = −19 → 18

  • k = −10 → 11

  • l = −23 → 22
Refinement

  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.060

  • wR(F2) = 0.159

  • S = 1.12

  • 5164 reflections

  • 336 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0829P)2 + 2.318P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 1.33 e Å−3

  • Δρmin = −0.46 e Å−3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 2431 Friedel pairs

  • Flack parameter: 0.11 (2)

Table 1
Selected geometric parameters (Å, °)[link]

Co1—O1 1.893 (4) 
Co1—O2 1.894 (4)
Co1—N3 1.917 (4)
Co1—N6 1.930 (4)
Co1—N2 1.959 (4)
Co1—N5 1.962 (4)
O1—Co1—O2 172.61 (19)
O1—Co1—N3 83.59 (16)
O2—Co1—N3 90.82 (17)
O1—Co1—N6 91.29 (16)
O2—Co1—N6 83.94 (15)
N3—Co1—N6 90.73 (16)
O1—Co1—N2 90.21 (16)
O2—Co1—N2 94.64 (15)
N3—Co1—N2 90.19 (16)
N6—Co1—N2 178.32 (16)
O1—Co1—N5 94.80 (16)
O2—Co1—N5 90.84 (17)
N3—Co1—N5 178.29 (17)
N6—Co1—N5 89.86 (15)
N2—Co1—N5 89.27 (16)

Attempts to solve the structure in space group Pcam with the central Co atom on a crystallographic twofold axis proved to be unsuccessful. Refinement and full convergence of the structure was achieved in the space group Pca21. H atoms were positioned geometrically and refined with a riding model, with C—H distances of 0.95–1.00 Å, N—H distances of 0.88 Å, and Uiso(H) values constrained to be 1.2 times Ueq of the carrier atom. The maximum residual electron density is 1.05 Å from atom O2.

Data collection: SMART (Bruker, 1997[Bruker (1997). SMART, SAINT, SHELXTL and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SMART; data reduction: SAINT (Bruker, 1997[Bruker (1997). SMART, SAINT, SHELXTL and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990[Sheldrick, G. M. (1990). Acta Cryst. A46, 467-473.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.]); molecular graphics: SHELXTL (Bruker, 1997[Bruker (1997). SMART, SAINT, SHELXTL and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S0108270105033913/fa1161sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270105033913/fa1161Isup2.hkl


Comment top

One of the crucial requirements for a metal to act as an electron carrier at biochemical redox centres is the availability of at least two readily accessible stable oxidation states of the metal that differ by one unit. Hence several of the first-row transition metals play major roles in a diverse range of enzymatic and electron-transfer processes in biological systems. Cobalt is well known for its role in the inorganic biochemistry of the cobalamins, rare examples of naturally occurring organometallic compounds (Cotton et al., 1999). At the centre of the coenzymes of the cobalamins, namely 5'-deoxyadenosylcobalamin (coenzyme B12) and methylcobalamin (MeB12), cobalt participates in catalytic radical-induced 1,2-rearrangement reactions and biomethylations, respectively (Lippard & Berg, 1994; Bertini & Luchinat, 1994; Kaim & Schwederski, 1994). In the catalytic cycles of these processes, cobalt shuttles between the divalent and trivalent states, and in MeB12 the relatively uncommon +1 state is also utilized (Drennan et al., 1994; Kräutler & Kratky, 1996).

The importance of low-spin cobalt(III) revolves around the kinetic inertness of its compounds, which has facilitated mechanistic studies in coordination chemistry. Virtually all octahedral cobalt(III) complexes are diamagnetic (configuration t2g6), with the exception of [CoF6]3− and [CoF3(H2O)3] (Cotton, et al., 1999). Generally, in coordination chemistry, CoIII is obtained from CoII by atmospheric or chemical oxidation (using oxidants such as H2O2). The title compound, [Co(C11H10N3O)2]ClO4, (I), was synthesized by reaction of Co(ClO4)2.6H2O with two molar equivalents of (2-pyridyl)bis(2-pyridylamino)methane (L1) (Galvez et al., 1986; Arulsamy & Hodgson, 1994) in EtOH in the presence of molecular oxygen at room temperature (see scheme). Compound (I) was also obtained from the template reaction of stoichiometric amounts of 2-pyridinecarboxaldehyde, 2-aminopyridine and Co(ClO4)2·6H2O in refluxing ethanol. Microanalyses (C, H and N) of a crystalline sample of (I) are consistent with the suggested chemical formulation of (I). The IR spectrum of this compound exhibits a sharp absorption at 3356 cm−1, confirming the presence of NH (secondary amine) in the ligand L2− synthesized in situ. The aliphatic and aromatic ν(C—H) absorptions occur at 2875 and 3080 cm−1, respectively. The pyridyl ring vibrations are indicated by the stretching frequencies in the range 1400–1620 cm−1. The uncoordinated perchlorate ion is characterized by an intense and broad absorption centred around 1090 cm−1 and a moderate and sharp band at 625 cm−1 (Nakamoto, 1997; Srinivasan et al., 2005).

As observed previously for other octahedral CoIII complexes with S = 0 (e.g. Mak et al., 1991; Emseis et al., 2004), the 1H NMR spectrum of [Co(L2)2]ClO4 in DMSO-d6 exhibits sharp resonances, showing that (I) is indeed diamagnetic. A signal corresponding to the secondary amine H atom is observed at 5.52 p.p.m., and several multiplets in the chemical shift range 6.22–8.85 p.p.m. are associated with the pyridyl H atoms. Further evidence for the singlet ground state of compound (I) is provided by UV–visible spectroscopy. The electronic spectrum of (I) (Fig. 1) displays a shoulder at 398 nm [partially obscured by an intense intraligand π → π* band at 315 nm (ε = 19500 M−1 cm−1)] and a weak band at 514 nm (ε = 80 M−1 cm−1), typical of low-spin CoIII complexes. Owing to the common chromophore CoIIIN4O2, regardless of the differences in the other moieties present, the related CoIII compounds carbonato-κ2O,O'- bis[2-(pyridyl-κN)amino-5,6-dihydro-4H-1,3-thiazine-κN]cobalt(III) choride (Barros-García et al., 2004), 4,11-diacetato-1,4,8,11-tetraazabicyclo[6.6.2] hexadecanecobalt(III) hexafluorophosphate (Lichty et al., 2004) and trans-bis(1,3-diamino-2-propanolato-N,N',O)cobalt(III) perchlorate (Bruce, 2003) have electronic spectra that resemble that of compound (I), with two cobalt-based absorptions in each case at 395 (shoulder) and 532 nm, 355 and 494 nm, and 394 and 498 nm, respectively. For all these aforementioned compounds, including (I), the two absorptions are attributable to ligand–field transitions; the higher-energy absorption represents the 1A1g → 1T2g transition, whereas the other is ascribed to the 1A1g → 1T1 g transition. Commonly, the higher-energy d–d band is masked by intraligand π → π* or LMCT bands (Djebbar-Sid et al., 2001; Tiliakos et al., 2001; Shongwe, Al-Hatmi et al., 2002 and/or Shongwe, Al-Juma & Fernandes, 2002; Saha et al., 2003; Barros-García et al., 2004). The pink–red colour of (I) is consistent with the electronic absorptions (Fig. 1).

Definitive evidence for the cobalt ion-assisted transformation of (2-pyridyl)bis (2-pyridylamino)methane (L1) to (2-pyridyl)bis(2-pyridylamino)methanolate (L2−) in situ was provided by single-crystal X-ray crystallography. Compound (I) was isolated at room temperature as pink–red block-shaped crystals; it crystallized in the orthorhombic space group Pca21. The crystal structure of (I) comprises a complex cation, [Co(L2)2]+, and a disordered perchlorate counter-anion (Fig. 2). The arrangement of the discrete mononuclear complex cations and counter-ions is shown in Fig. 3. Selected bond distances and angles are given in Table 1. The crystal structure of the complex cation shows two tridentate (2-pyridyl)bis(2-pyridylamino)methanolate ligands coordinated facially to the cobalt(III) ion to form a distorted octahedral geometry. The distortion, evidenced by deviations from idealized Oh angles and differences in bond distances in the coordination sphere, is a consequence of ligand constraints. The cobalt(III) ion resides on a pseudo-twofold axis of symmetry and on an equatorial plane formed by the pyridyl N atoms of the two ligands. The methanolate O atoms, in the axial positions [O1—Co1—O2 = 172.61 (19)°], have stronger interactions with the central metal atom [CoIII—Omethanolate = 1.893 (4) and 1.894 (4) Å] than do the pyridyl N atoms (Table 1). The CoIII—Omethanolate distances compare favourably with the CoIII—Opropanolate [1.867 (6) and 1.921 (5) Å; Bruce, 2003], CoIII–Ocarboxylate [1.882 (6) and 1.916 (3) Å; Shongwe, Al-Hatmi et al., 2002 and/or Shongwe, Al-Juma & Fernandes, 2002; Lichty et al., 2004], CoIII–Onaphtholate [1.886 (4)–1.9139 (17) Å; Kurahashi, 1976; Shongwe, Al-Hatmi et al., 2002 and/or Shongwe, Al-Juma & Fernandes, 2002], CoIII–Ophenolate [1.862 (6)–1.928 (2) Å; Nassimbeni et al., 1976; Chen et al., 1991; Shongwe, Al-Hatmi et al., 2002 and/or Shongwe, Al-Juma & Fernandes, 2002] and CoIII–Ocarbonate [1.907 (2) and 1.919 (2) Å; Barros-García et al., 2004]. Likewise, the CoIII–Npyridyl distances of (I) [1.917 (4)–1.962 (4) Å] are normal (Tiliakos et al., 2001; Ghiladi et al., 2003; Barros-García et al., 2004; Stamatatos et al., 2005). Owing to steric constraints, the two CoIII–Npyridyl distances (for each L2− ligand) in (I) are significantly different (by 0.044 Å). Similar behaviour has been demonstrated by the CoIII complex of deprotonated N,N'-bis(2-pyridyl)urea (Tiliakos et al., 2001).

The metal ion-assisted conversion of L1 to L2− has been demonstrated previously (Arulsamy & Hodgson, 1994) using manganese(II) and iron(II) to form the MIII complexes [Mn(L2)2]ClO4 and [Fe(L2)2]ClO4, respectively, chemically isostructural with [Co(L2)2]ClO4, (I). It is noteworthy that in the case of the high-spin (t2g3eg1) MnIII analogue, the equatorial bonds (Mn—Npyridyl) appear elongated in accordance with the Jahn–Teller effect (evident axial compression). In the reaction of MII (M = Mn, Fe or Co) with L1 in air, oxygen is inserted into the ligand at the aliphatic C atom, causing deamination as shown in the scheme. Cytochrome P450-dependent incorporation of O atoms from freely available molecular oxygen into organic chemical substrates occurs extensively in nature (Kaim & Schwederski, 1994). In our system, we and others (Arulsamy & Hodgson, 1994) have shown that a crucial requirement for the oxidative degradation of the aminal ligand L1 is accessibility of a stable MIII oxidation state. Oxygenation of the ligand occurs in conjunction with oxidation of the MII ions. In the case of Ni2+ (Arulsamy & Hodgson, 1994) and Cu2+, the ligand L1 remains intact during the reaction.

Experimental top

L1 was synthesized following literature procedures (Galvez et al., 1986; Arulsamy & Hodgson, 1994). A solution of 2-aminopyridine (4.7152 g, 0.050 mol) in ethanol (20 ml) was mixed with a solution of 2-pyridinecarboxaldehyde (2.6780 g, 0.025 mol) in ethanol (20 ml) to give a light-yellow–brown solution. This solution was heated under reflux for 10 h, during which time its colour remained essentially the same. Slow evaporation of the solution at room temperature over a period of five days gave blocks of colourless crystals, which were washed several times with ice-cold ethanol and dried in air. (Yield 6.1012 g, 88.0%; m.p. 389–391 K.) Microanalysis found: C 69.40, H 5.47, N 25.15%; calculated for C16H15N5 (Mr = 277.328): C 69.30, H 5.45, N 25.25%; IR (KBr1, cm−1): 3290, 3245 (N–H); UV–vis (DMSO, nm): 260 (ε = 15500 M−1 cm−1), 300 (ε = 9540 M−1 cm−1). For the preparation of (I), Co(ClO4)2·6H2O (0.1464 g, 0.40 mmol) was added to a solution of L1 (0.2219 g, 0.80 mmol) in ethanol (20 ml); an orange solution formed immediately and progressively darkened with time during continuous stirring at room temperature. After 5 min of stirring, the pink–red solution was filtered and kept at room temperature. Within three days of slow evaporation, bright pink–red blocks of crystals were deposited. After one week, the crystals had grown larger and become dark red. The crystals were washed with ice-cold ethanol and dried in air. (Yield 0.1375 g, 61.5%.) [Co(L2)2]ClO4 was also obtained in higher yield (75%) from the template reaction of stoichiometric amounts (0.20 mmol scale based on the CoII salt) of 2-aminopyridine, 2-pyridinecarboxaldehyde and Co(ClO4)2·6H2O. (M.p. 514–515 K.) Microanalysis found: C 47.20, H 3.62, N 14.94%; calculated for C22H20ClCoN6O6 (Mr 558.82): C 47.29, H 3.61, N 15.04%; IR (KBr, cm−1): 3356 (N–H), 1090, 625 (ClO4−); UV–vis (DMSO, nm): 263 (ε = 19500 M−1 cm−1), 315 (ε = 7800 M−1 cm−1), 398 (shoulder), 514 (ε = 80 M−1 cm−1); 1H NMR (DMSO-d6, p.p.m.): δ 5.52 (d), 6.22–8.85 (m).

Refinement top

Attempts to solve the structure in space group Pcam with the central Co atom on a crystallographic twofold axis proved to be unsuccessful. Refinement and full convergence of the structure was achieved in space group Pca21. H atoms were positioned geometrically and refined with a riding model, with C—H distances of 0.95–1.00 Å, N—H distances of 0.88 Å, and Uiso(H) values constrained to be 1.2 times Ueq of the carrier atom. The maximum residual electron density is 1.05 Å from O2. Please check changes to text.

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The electronic absorption spectrum of (I) in DMSO: 0.10 mM (lower line) and 3.0 mM (higher line).
[Figure 2] Fig. 2. The crystal structure of (I), showing the mononuclear complex cation and the disordered perchlorate counter-ion.
[Figure 3] Fig. 3. The packing of (I).
Bis[(2-pyridyl)(2-pyridylamino)methanolato]cobalt(III) perchlorate top
Crystal data top
[Co(C11H10N3O)2]ClO4Dx = 1.632 Mg m−3
Mr = 558.82Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pca21Cell parameters from 1903 reflections
a = 14.802 (3) Åθ = 2.3–27.6°
b = 8.6144 (18) ŵ = 0.93 mm−1
c = 17.832 (4) ÅT = 150 K
V = 2273.8 (8) Å3Block, red
Z = 40.32 × 0.12 × 0.12 mm
F(000) = 1144
Data collection top
Bruker SMART 1000
diffractometer		5164 independent reflections
Radiation source: fine-focus sealed tube4598 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.065
Detector resolution: 100 pixels mm-1θmax = 27.6°, θmin = 2.3°
ω scansh = −19→18
Absorption correction: multi-scan
(SADABS; Bruker, 1997)		k = −10→11
Tmin = 0.756, Tmax = 0.897l = −23→22
23722 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.060H-atom parameters constrained
wR(F2) = 0.159 w = 1/[σ2(Fo2) + (0.0829P)2 + 2.318P]
where P = (Fo2 + 2Fc2)/3
S = 1.12(Δ/σ)max = 0.001
5164 reflectionsΔρmax = 1.33 e Å−3
336 parametersΔρmin = −0.46 e Å−3
157 restraintsAbsolute structure: Flack (1983), 2431 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.11 (2)
Crystal data top
[Co(C11H10N3O)2]ClO4V = 2273.8 (8) Å3
Mr = 558.82Z = 4
Orthorhombic, Pca21Mo Kα radiation
a = 14.802 (3) ŵ = 0.93 mm−1
b = 8.6144 (18) ÅT = 150 K
c = 17.832 (4) Å0.32 × 0.12 × 0.12 mm
Data collection top
Bruker SMART 1000
diffractometer		5164 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1997)		4598 reflections with I > 2σ(I)
Tmin = 0.756, Tmax = 0.897Rint = 0.065
23722 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.060H-atom parameters constrained
wR(F2) = 0.159Δρmax = 1.33 e Å−3
S = 1.12Δρmin = −0.46 e Å−3
5164 reflectionsAbsolute structure: Flack (1983), 2431 Friedel pairs
336 parametersAbsolute structure parameter: 0.11 (2)
157 restraints
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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)
Co10.24559 (5)1.01485 (6)0.02269 (6)0.02530 (17)
N10.3694 (3)0.7771 (6)0.1108 (2)0.0393 (10)
H10.40990.72390.13620.047*
N20.2862 (2)0.8041 (4)−0.0012 (2)0.0250 (8)
N30.1814 (3)0.9376 (4)0.1083 (2)0.0245 (8)
N40.1840 (3)1.1709 (6)−0.1290 (3)0.0391 (10)
H40.16051.1982−0.17240.047*
N50.3146 (3)1.0928 (4)−0.0633 (2)0.0253 (8)
N60.2040 (3)1.2228 (4)0.0433 (2)0.0260 (8)
O10.3417 (3)1.0368 (4)0.0919 (2)0.0347 (8)
O20.1396 (3)1.0026 (4)−0.0366 (2)0.0336 (9)
C10.3440 (3)0.7226 (6)0.0433 (2)0.0278 (8)
C20.2595 (3)0.7382 (6)−0.0671 (3)0.0312 (9)
H20.21670.7925−0.09690.037*
C30.2902 (3)0.6010 (6)−0.0926 (3)0.0343 (8)
H30.27100.5618−0.13980.041*
C40.3509 (4)0.5169 (6)−0.0482 (3)0.0338 (8)
H4A0.37430.4201−0.06480.041*
C50.3762 (3)0.5777 (5)0.0205 (3)0.0314 (8)
H50.41560.52070.05230.038*
C60.3340 (3)0.9183 (7)0.1442 (3)0.0366 (9)
H60.36940.94490.19030.044*
C70.2348 (3)0.8920 (6)0.1647 (3)0.0330 (8)
C80.2016 (4)0.8321 (6)0.2308 (3)0.0374 (8)
H80.24130.80210.27000.045*
C90.1093 (4)0.8167 (6)0.2388 (3)0.0428 (9)
H90.08450.77510.28360.051*
C100.0539 (4)0.8619 (6)0.1813 (3)0.0417 (9)
H10−0.00970.85090.18610.050*
C110.0904 (3)0.9238 (6)0.1160 (3)0.0364 (9)
H110.05160.95650.07660.044*
C120.2746 (3)1.1519 (5)−0.1246 (3)0.0259 (8)
C130.3277 (4)1.2015 (6)−0.1864 (3)0.0325 (8)
H130.29961.2429−0.22990.039*
C140.4196 (4)1.1894 (6)−0.1827 (3)0.0373 (9)
H140.45561.2220−0.22390.045*
C150.4601 (3)1.1297 (6)−0.1190 (3)0.0372 (9)
H150.52401.1220−0.11540.045*
C160.4064 (3)1.0824 (6)−0.0620 (3)0.0347 (9)
H160.43431.0397−0.01870.042*
C170.1241 (3)1.1484 (6)−0.0658 (3)0.0354 (9)
H170.05991.1563−0.08290.042*
C180.1435 (3)1.2756 (6)−0.0067 (3)0.0334 (8)
C190.1046 (4)1.4184 (6)−0.0006 (3)0.0375 (9)
H190.06251.4535−0.03710.045*
C200.1273 (4)1.5098 (6)0.0590 (4)0.0439 (10)
H200.10121.61000.06390.053*
C210.1871 (4)1.4583 (7)0.1116 (3)0.0418 (9)
H210.20151.52120.15370.050*
C220.2280 (4)1.3096 (6)0.1029 (3)0.0370 (10)
H220.27101.27270.13820.044*
Cl10.42351 (7)0.49852 (13)0.26271 (5)0.0309 (3)
O30.3445 (8)0.410 (2)0.2458 (9)0.049 (3)0.52 (3)
O3'0.3764 (12)0.3605 (14)0.2413 (9)0.051 (3)0.48 (3)
O40.3815 (3)0.6404 (5)0.2853 (3)0.0709 (15)
O50.4783 (3)0.5337 (5)0.1990 (2)0.0426 (9)
O60.4769 (3)0.4433 (6)0.3239 (2)0.0527 (11)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Co10.0303 (3)0.0205 (3)0.0251 (3)−0.0047 (2)−0.0116 (2)0.0057 (3)
N10.0280 (19)0.061 (3)0.029 (2)0.0086 (19)−0.0059 (16)−0.003 (2)
N20.0286 (17)0.0226 (19)0.0238 (17)−0.0038 (15)−0.0059 (14)0.0061 (14)
N30.0279 (18)0.0208 (17)0.0249 (19)−0.0036 (14)−0.0075 (14)0.0034 (15)
N40.034 (2)0.052 (3)0.031 (2)0.0114 (19)−0.0072 (17)−0.013 (2)
N50.0322 (19)0.0193 (17)0.0245 (19)−0.0040 (14)−0.0067 (15)0.0021 (15)
N60.0352 (18)0.0233 (17)0.0194 (18)−0.0078 (15)−0.0034 (14)0.0008 (13)
O10.0373 (19)0.0327 (18)0.034 (2)−0.0110 (15)−0.0172 (16)0.0102 (16)
O20.0361 (19)0.0201 (17)0.045 (2)−0.0069 (13)−0.0200 (17)0.0093 (14)
C10.0264 (17)0.0323 (19)0.0247 (19)0.0024 (15)0.0019 (15)0.0042 (15)
C20.036 (2)0.034 (2)0.0229 (18)−0.0084 (16)−0.0047 (16)−0.0002 (17)
C30.0411 (18)0.0331 (18)0.0289 (17)−0.0105 (16)0.0022 (15)−0.0037 (15)
C40.0386 (18)0.0291 (17)0.0337 (18)−0.0062 (14)0.0094 (16)−0.0013 (15)
C50.0319 (16)0.0310 (17)0.0313 (17)0.0041 (14)0.0068 (15)0.0061 (16)
C60.0391 (19)0.043 (2)0.027 (2)0.0048 (19)−0.0065 (17)−0.0053 (18)
C70.0393 (18)0.0346 (19)0.0251 (17)0.0070 (16)0.0005 (15)0.0004 (16)
C80.0512 (18)0.0300 (18)0.0311 (18)0.0089 (16)0.0066 (16)0.0024 (16)
C90.0537 (19)0.0301 (19)0.0445 (19)0.0012 (17)0.0158 (17)−0.0015 (17)
C100.0399 (18)0.0309 (19)0.054 (2)−0.0012 (16)0.0133 (16)−0.0104 (17)
C110.033 (2)0.025 (2)0.051 (2)0.0019 (17)−0.0021 (18)−0.0082 (18)
C120.0346 (19)0.0230 (18)0.0202 (17)0.0019 (16)−0.0017 (15)−0.0009 (15)
C130.0447 (18)0.0267 (18)0.0263 (17)0.0048 (16)0.0047 (15)0.0005 (15)
C140.0433 (18)0.0272 (18)0.0413 (18)−0.0031 (16)0.0100 (16)−0.0022 (16)
C150.0316 (18)0.0288 (18)0.051 (2)−0.0022 (15)−0.0012 (15)−0.0063 (16)
C160.0303 (19)0.028 (2)0.046 (2)0.0025 (16)−0.0111 (16)−0.0028 (18)
C170.0314 (19)0.040 (2)0.035 (2)0.0034 (18)−0.0017 (17)0.0035 (18)
C180.0319 (17)0.0351 (18)0.0333 (18)0.0067 (15)0.0062 (15)0.0050 (16)
C190.0366 (18)0.0333 (18)0.0426 (19)0.0037 (16)0.0141 (16)0.0037 (15)
C200.043 (2)0.0361 (19)0.053 (2)−0.0044 (16)0.0167 (17)−0.0053 (16)
C210.046 (2)0.0378 (19)0.042 (2)−0.0156 (17)0.0164 (16)−0.0159 (17)
C220.041 (2)0.038 (2)0.032 (2)−0.0163 (17)0.0067 (18)−0.0082 (19)
Cl10.0309 (5)0.0407 (6)0.0212 (5)−0.0057 (4)−0.0008 (5)0.0070 (4)
O30.041 (5)0.061 (7)0.044 (4)−0.022 (5)−0.001 (5)−0.002 (5)
O3'0.041 (6)0.066 (7)0.045 (4)−0.026 (5)−0.002 (6)0.000 (5)
O40.061 (3)0.083 (4)0.068 (3)0.041 (3)0.012 (2)0.013 (3)
O50.0388 (19)0.049 (2)0.040 (2)−0.0011 (18)0.0103 (17)0.0137 (19)
O60.050 (2)0.070 (3)0.039 (2)0.017 (2)−0.0053 (19)0.022 (2)
Geometric parameters (Å, º) top
Co1—O11.893 (4)C7—C81.378 (7)
Co1—O21.894 (4)C8—C91.380 (8)
Co1—N31.917 (4)C8—H80.9500
Co1—N61.930 (4)C9—C101.369 (9)
Co1—N21.959 (4)C9—H90.9500
Co1—N51.962 (4)C10—C111.390 (8)
N1—C11.344 (6)C10—H100.9500
N1—C61.453 (7)C11—H110.9500
N1—H10.8800C12—C131.419 (7)
N2—C11.363 (6)C13—C141.365 (7)
N2—C21.364 (6)C13—H130.9500
N3—C71.339 (6)C14—C151.384 (8)
N3—C111.359 (6)C14—H140.9500
N4—C121.353 (6)C15—C161.353 (8)
N4—C171.448 (7)C15—H150.9500
N4—H40.8800C16—H160.9500
N5—C121.344 (6)C17—C181.547 (8)
N5—C161.362 (6)C17—H171.0000
N6—C181.344 (6)C18—C191.362 (7)
N6—C221.346 (6)C19—C201.365 (8)
O1—C61.388 (7)C19—H190.9500
O2—C171.379 (6)C20—C211.364 (9)
C1—C51.397 (7)C20—H200.9500
C2—C31.345 (7)C21—C221.425 (8)
C2—H20.9500C21—H210.9500
C3—C41.400 (8)C22—H220.9500
C3—H30.9500Cl1—O51.428 (2)
C4—C51.384 (8)Cl1—O41.429 (2)
C4—H4A0.9500Cl1—O61.429 (2)
C5—H50.9500Cl1—O31.430 (3)
C6—C71.529 (7)Cl1—O3'1.430 (3)
C6—H61.0000
O1—Co1—O2172.61 (19)C8—C7—C6127.1 (5)
O1—Co1—N383.59 (16)C7—C8—C9118.6 (5)
O2—Co1—N390.82 (17)C7—C8—H8120.7
O1—Co1—N691.29 (16)C9—C8—H8120.7
O2—Co1—N683.94 (15)C10—C9—C8119.2 (5)
N3—Co1—N690.73 (16)C10—C9—H9120.4
O1—Co1—N290.21 (16)C8—C9—H9120.4
O2—Co1—N294.64 (15)C9—C10—C11120.3 (5)
N3—Co1—N290.19 (16)C9—C10—H10119.9
N6—Co1—N2178.32 (16)C11—C10—H10119.9
O1—Co1—N594.80 (16)N3—C11—C10120.2 (5)
O2—Co1—N590.84 (17)N3—C11—H11119.9
N3—Co1—N5178.29 (17)C10—C11—H11119.9
N6—Co1—N589.86 (15)N5—C12—N4122.0 (4)
N2—Co1—N589.27 (16)N5—C12—C13120.1 (4)
C1—N1—C6124.0 (4)N4—C12—C13117.9 (4)
C1—N1—H1118.0C14—C13—C12119.5 (5)
C6—N1—H1118.0C14—C13—H13120.3
C1—N2—C2118.0 (4)C12—C13—H13120.3
C1—N2—Co1122.9 (3)C13—C14—C15120.0 (5)
C2—N2—Co1119.0 (3)C13—C14—H14120.0
C7—N3—C11118.9 (4)C15—C14—H14120.0
C7—N3—Co1114.1 (3)C16—C15—C14118.3 (5)
C11—N3—Co1127.0 (3)C16—C15—H15120.9
C12—N4—C17123.1 (4)C14—C15—H15120.9
C12—N4—H4118.5C15—C16—N5123.6 (5)
C17—N4—H4118.5C15—C16—H16118.2
C12—N5—C16118.6 (4)N5—C16—H16118.2
C12—N5—Co1122.4 (3)O2—C17—N4108.3 (4)
C16—N5—Co1118.9 (3)O2—C17—C18110.9 (4)
C18—N6—C22120.8 (4)N4—C17—C18108.8 (4)
C18—N6—Co1113.6 (3)O2—C17—H17109.6
C22—N6—Co1125.6 (3)N4—C17—H17109.6
C6—O1—Co1107.6 (3)C18—C17—H17109.6
C17—O2—Co1107.3 (3)N6—C18—C19122.3 (5)
N1—C1—N2121.1 (4)N6—C18—C17109.7 (4)
N1—C1—C5118.5 (4)C19—C18—C17128.0 (5)
N2—C1—C5120.3 (4)C18—C19—C20118.6 (5)
C3—C2—N2124.0 (5)C18—C19—H19120.7
C3—C2—H2118.0C20—C19—H19120.7
N2—C2—H2118.0C19—C20—C21120.5 (5)
C2—C3—C4118.8 (5)C19—C20—H20119.8
C2—C3—H3120.6C21—C20—H20119.8
C4—C3—H3120.6C20—C21—C22119.6 (5)
C5—C4—C3118.6 (5)C20—C21—H21120.2
C5—C4—H4A120.7C22—C21—H21120.2
C3—C4—H4A120.7N6—C22—C21118.2 (5)
C4—C5—C1120.3 (5)N6—C22—H22120.9
C4—C5—H5119.9C21—C22—H22120.9
C1—C5—H5119.9O5—Cl1—O4106.9 (3)
O1—C6—N1108.0 (4)O5—Cl1—O6111.3 (3)
O1—C6—C7110.4 (4)O4—Cl1—O6108.0 (3)
N1—C6—C7108.7 (4)O5—Cl1—O3114.2 (7)
O1—C6—H6109.9O4—Cl1—O399.4 (8)
N1—C6—H6109.9O6—Cl1—O3115.8 (7)
C7—C6—H6109.9O5—Cl1—O3'104.0 (7)
N3—C7—C8122.8 (5)O4—Cl1—O3'125.0 (9)
N3—C7—C6110.1 (4)O6—Cl1—O3'101.4 (8)

Experimental details

Crystal data
Chemical formula[Co(C11H10N3O)2]ClO4
Mr558.82
Crystal system, space groupOrthorhombic, Pca21
Temperature (K)150
a, b, c (Å)14.802 (3), 8.6144 (18), 17.832 (4)
V (Å3)2273.8 (8)
Z4
Radiation typeMo Kα
µ (mm−1)0.93
Crystal size (mm)0.32 × 0.12 × 0.12
Data collection
DiffractometerBruker SMART 1000
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1997)
Tmin, Tmax0.756, 0.897
No. of measured, independent and
observed [I > 2σ(I)] reflections		23722, 5164, 4598
Rint0.065
(sin θ/λ)max (Å−1)0.652
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.060, 0.159, 1.12
No. of reflections5164
No. of parameters336
No. of restraints157
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)1.33, −0.46
Absolute structureFlack (1983), 2431 Friedel pairs
Absolute structure parameter0.11 (2)

Computer programs: SMART (Bruker, 1997), SMART, SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXTL.

Selected geometric parameters (Å, º) top
Co1—O11.893 (4)Co1—N61.930 (4)
Co1—O21.894 (4)Co1—N21.959 (4)
Co1—N31.917 (4)Co1—N51.962 (4)
O1—Co1—O2172.61 (19)N3—Co1—N290.19 (16)
O1—Co1—N383.59 (16)N6—Co1—N2178.32 (16)
O2—Co1—N390.82 (17)O1—Co1—N594.80 (16)
O1—Co1—N691.29 (16)O2—Co1—N590.84 (17)
O2—Co1—N683.94 (15)N3—Co1—N5178.29 (17)
N3—Co1—N690.73 (16)N6—Co1—N589.86 (15)
O1—Co1—N290.21 (16)N2—Co1—N589.27 (16)
O2—Co1—N294.64 (15)
 

Acknowledgements

DOPSAR, Sultan Qaboos University, is gratefully acknowledged for financial support to MSS (grant No. IG/SCI/CHEM/03/02).

References

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Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296
Volume 61| Part 12| December 2005| Pages m497-m500
doi:10.1107/S0108270105033913
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