A dimeric cobalt(II)-suberate complex with 3-amino­pyridine

The title complex, [mu]-octane-1,8-dioato-bis[bis(3-aminopyridine)chloro(methanol)cobalt(II)], [Co₂(C₈H₁₂O₄)Cl₂(C₅H₆N₂)₄(CH₄O)₂], is located on a crystallographic centre of inversion. The coordination around each of the Co centres is distorted octa­hedral, involving two N, three O and one Cl atom. Discrete dimers are connected in a three-dimensional arrangement through N-H...O, N-H...Cl and O-H...O hydrogen-bond inter­actions.

S1. Comment

Carboxylate ligands are one of the most widely used class of bridging ligands in coordination chemistry. The versatility of the carboxylate group is illustrated by a variety of coordination modes in which it connects metal centers, the most common being the so-called syn–syn, syn–anti and anti–anti modes. The versatility can be enhanced by ligands that contain more than one carboxylate group (di-, tri- and polycarboxylates). Among them α,ω-aliphatic dicarboxylates are interesting not just because they contain two terminal functional carboxylate groups, but also by the fact that these two groups are linked by flexible alkyl chains which by their conformational freedom offer a greater degree of structural diversity. In recent years our research has been devoted to the synthesis and structural analysis of metal complexes with monocarboxylates and different aminopyridines (see for example Lah, Giester, Lah et al., 2001; Lah, Giester, Šegedin et al., 2001; Lah et al., 2002; Kozlevcar et al., 2004). As a part of our ongoing project we have extended our investigations to metal complexes with saturated α,ω-aliphatic dicarboxylates. We report here the synthesis and crystal structure of a dimeric Co^II complex with anions of suberic acid (1,8-octanedioic acid) and 3-aminopyridine and discuss its structure in terms of the known structurally characterized metal–suberate complexes.

Despite our attempts to prepare a new coordination polymer of higher dimensions, compound (I) (Fig. 1) exists as a centrosymmetric dimer in which the suberate dianion (SA) connects two cobalt ions with both carboxylate groups simultaneously adopting chelating bidentate modes. The coordination around the metal center is completed by two 3-aminopyridine ligands coordinated through endocyclic N atoms, a chloride anion and a methanol molecule (Table 1). Thus, each Co center has a distorted octahedral geometry. The central C atoms of the alkyl chain adopt a trans conformation [C2—C3—C4—C4ⁱ = 178.6 (2)°; (i) −x + 2, −y, −z + 1] while the C1—C2—C3—C4 torsion angle of −64.3 (3)° indicates gauche geometry. The presence of several hydrogen-bond donors and acceptors anticipates a complex hydrogen-bonding scheme. Apparently, the orientation of the 3-aminopyridine ligands and the location of the amino groups on meta positions prevent the formation of intramolecular hydrogen bonds. However, both crystallographically independent amino groups and the methanol molecule are, as donors, involved in the formation of hydrogen bonds. One of the amino groups (N12) donates both H atoms to the Cl atoms of two different neighbouring dimeric units. Taking into account a center of symmetry, the result is the formation of an eight-membered ring. The second amino group (N22) participates in hydrogen bonding with one H atom only, which is in contact with the carboxylate O atom of the adjacent molecule (Fig 2). The two-dimensional layers that are formed by hydrogen-bond contacts including the NH₂ groups are further connected into a three-dimensional arrangement through O—H···O interactions between methanol and carboxylate O atoms of neighbouring units (Fig. 3). See Table 2 for details of the hydrogen bonding.

A search of the Cambridge Structural Database (Version 5.27 with August 2006 update; Allen, 2002) gave 26 hits for transition metal complexes with coordinated suberic acid or its anions (either hydrogensuberate or suberate dianions). Most of them (18) are polymers with dimensions varying from one-dimensional to three-dimensional. Only eight examples of structures with discrete entities are known, viz. three manganes dimers (Zheng & Lin, 2001; Zheng & Kong, 2003 or Zheng, Lin & Kong, 2003), a zinc monomer and a dimer (Wei et al., 2002), a copper monomer and a dimer (McCann et al., 1995; Devereux et al., 1999) and one example of a cobalt dimer (Zheng & Kong, 2003 or Zheng, Lin & Kong, et al., 2003). There is one feature common to all these discrete structures; they all contain additional bifunctioinal N-ligands (1,10-phenantroline or 2,2'-bipyridine) that by chelation occupy two coordination sites and are large enough to prevent further interactions with larger ligands in the directions to polymer formation. The above-mentioned cobalt dimer has [Co₂(phen)₂(H₂O)₂(SA)₂] stoichiometry. The two cobalt ions, in a severely distorted octahedral environment, are linked by two SA dianions that serves as tridentate ligands with one of the carboxylate groups involved in chelation and the second coordinated in a monodentate fashion. The remaining coordination sites on Co are occupied by phenanthroline N atoms and water molecules. The related system of oxalate as the first from the holologue series of α,ω-dicarboxylates and aminopyridines has already been investigated in cobalt, nickel and copper chemistry (Castillo et al., 2001). However, the structures of none of the reported complexes resemble that of (I); all the reported compounds are polymers.

S2. Experimental

CoCl₂·6H₂O (0.40 g, 1.68 mmol) and suberic acid (0.29 g, 1.67 mmol) were combined in 7.0 ml of methanol. The resulting pink mixture was stirred for 20 min. 3-Aminopyridine (0.20 g, 2.13 mmol) was added, and the resulting deep-blue solution was stirred for 1 h and then filtered. On cooling of the filtrate to 278 K, the colour changed from blue to violet. The change of colour upon cooling/heating is reversible. On standing at 278 K, violet prismatic crystals formed in 66% yield.

S3. Refinement

All H atoms (except those of the MeOH hydroxy group and amino groups) were placed in geometrically calculated positions (C—H = 0.93–0.97 Å) and were refined using a riding model. The hydoxy H atom (H1M) and the H atoms of the amino groups (H12A, H12B, H22A and H22B) were found in the difference Fourier map and were freely refined.

Computing details

Data collection: Collect (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO AND SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia,1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003).

Figures

	Fig. 1. The dimeric structure of (I). Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity. [Symmetry code: (i) −x + 2, −y, −z + 1.]
	Fig. 2. Two-dimensional layers in (I), formed by hydrogen bonds including NH2 groups. C-bound H atoms have been omitted.
	Fig. 3. A packing diagram of (I), viewed along the a axis, showing the complete hydrogen-bonding scheme. C-bound H atoms have been omitted.

tetrakis(3-aminopyridine)dichloro-bis(methanol)-µ2-suberato-dicobalt(II)

Crystal data

[Co2(C5H6N2)4(CH4O)2Cl2(C8H12O4)]	Z = 1
Mr = 801.49	F(000) = 416
Triclinic, P1	Dx = 1.491 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71069 Å
a = 7.3955 (2) Å	Cell parameters from 3157 reflections
b = 11.2390 (3) Å	θ = 1.0–26.4°
c = 11.7463 (3) Å	µ = 1.13 mm^−1
α = 104.505 (1)°	T = 150 K
β = 106.052 (1)°	Prism, violet
γ = 95.888 (1)°	0.12 × 0.12 × 0.10 mm
V = 892.73 (4) Å^3

Data collection

Nonius KappaCCD diffractometer	3185 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.018
Graphite monochromator	θmax = 26.3°, θmin = 3.5°
ω scans at κ=55°	h = −9→9
6468 measured reflections	k = −13→14
3599 independent reflections	l = −14→14

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.072	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0222P)^2 + 0.7104P] where P = (Fo^2 + 2Fc^2)/3
3599 reflections	(Δ/σ)max = 0.005
238 parameters	Δρmax = 0.81 e Å^−3
0 restraints	Δρmin = −0.32 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Co1	0.83083 (4)	0.36023 (2)	0.26676 (2)	0.01840 (9)
Cl1	1.09870 (7)	0.48057 (5)	0.24732 (4)	0.02239 (12)
O1	0.92758 (19)	0.32824 (13)	0.44642 (12)	0.0217 (3)
O2	0.6284 (2)	0.26129 (13)	0.33218 (13)	0.0246 (3)
C1	0.7627 (3)	0.26816 (18)	0.42889 (18)	0.0210 (4)
C2	0.7289 (3)	0.2055 (2)	0.5226 (2)	0.0262 (5)
H2A	0.6108	0.1445	0.4846	0.031*
H2B	0.7131	0.2678	0.5913	0.031*
C3	0.8914 (4)	0.1401 (2)	0.5725 (2)	0.0347 (5)
H3A	1.0099	0.2009	0.6086	0.042*
H3B	0.8665	0.1097	0.6381	0.042*
C4	0.9180 (4)	0.0319 (2)	0.4762 (2)	0.0348 (5)
H4A	0.9394	0.0620	0.4096	0.042*
H4B	0.8005	−0.0297	0.4416	0.042*
N11	0.6291 (2)	0.34125 (15)	0.09381 (15)	0.0220 (4)
C12	0.4518 (3)	0.36211 (18)	0.0832 (2)	0.0242 (4)
H12	0.4129	0.3792	0.1535	0.029*
C13	0.3210 (3)	0.35911 (19)	−0.0311 (2)	0.0281 (5)
C14	0.3824 (3)	0.3329 (2)	−0.1349 (2)	0.0328 (5)
H14	0.3005	0.3310	−0.2115	0.039*
C15	0.5631 (3)	0.3099 (2)	−0.1240 (2)	0.0328 (5)
H15	0.6048	0.2914	−0.1932	0.039*
C16	0.6838 (3)	0.3144 (2)	−0.00876 (19)	0.0274 (5)
H16	0.8067	0.2983	−0.0019	0.033*
N12	0.1381 (3)	0.37748 (19)	−0.0389 (2)	0.0345 (5)
N21	0.9065 (2)	0.18399 (15)	0.19406 (15)	0.0206 (4)
C22	1.0871 (3)	0.16606 (19)	0.22372 (19)	0.0231 (4)
H22	1.1840	0.2353	0.2676	0.028*
C23	1.1384 (3)	0.0490 (2)	0.19239 (19)	0.0244 (4)
C24	0.9901 (3)	−0.05349 (19)	0.1266 (2)	0.0269 (5)
H24	1.0166	−0.1336	0.1039	0.032*
C25	0.8037 (3)	−0.0341 (2)	0.0958 (2)	0.0276 (5)
H25	0.7035	−0.1012	0.0513	0.033*
C26	0.7663 (3)	0.08437 (19)	0.13102 (19)	0.0249 (5)
H26	0.6399	0.0959	0.1105	0.030*
N22	1.3262 (3)	0.0353 (2)	0.2280 (2)	0.0361 (5)
O1M	0.7753 (2)	0.53724 (14)	0.35736 (13)	0.0205 (3)
C1M	0.6415 (3)	0.5548 (2)	0.4250 (2)	0.0319 (5)
H1A	0.5157	0.5126	0.3716	0.048*
H1B	0.6414	0.6425	0.4550	0.048*
H1C	0.6775	0.5212	0.4938	0.048*
H1M	0.873 (4)	0.574 (3)	0.398 (2)	0.035 (8)*
H22A	1.407 (4)	0.100 (3)	0.253 (3)	0.047 (8)*
H12A	0.130 (4)	0.419 (3)	0.043 (3)	0.062 (9)*
H22B	1.354 (4)	−0.034 (3)	0.196 (3)	0.052 (9)*
H12B	0.073 (5)	0.413 (3)	−0.110 (3)	0.070 (10)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.01630 (15)	0.01797 (15)	0.01848 (15)	0.00144 (10)	0.00128 (11)	0.00639 (11)
Cl1	0.0187 (2)	0.0230 (3)	0.0240 (3)	0.00067 (19)	0.00496 (19)	0.0076 (2)
O1	0.0185 (7)	0.0219 (7)	0.0224 (7)	0.0008 (6)	0.0027 (6)	0.0076 (6)
O2	0.0211 (7)	0.0243 (8)	0.0274 (8)	0.0018 (6)	0.0033 (6)	0.0115 (6)
C1	0.0226 (10)	0.0168 (10)	0.0234 (10)	0.0056 (8)	0.0064 (9)	0.0056 (8)
C2	0.0294 (11)	0.0256 (11)	0.0269 (11)	0.0049 (9)	0.0110 (9)	0.0110 (9)
C3	0.0449 (14)	0.0323 (13)	0.0280 (12)	0.0072 (11)	0.0074 (11)	0.0149 (10)
C4	0.0442 (14)	0.0290 (12)	0.0342 (13)	0.0107 (11)	0.0091 (11)	0.0167 (10)
N11	0.0206 (9)	0.0183 (8)	0.0236 (9)	0.0011 (7)	0.0013 (7)	0.0069 (7)
C12	0.0225 (11)	0.0176 (10)	0.0271 (11)	0.0009 (8)	0.0004 (9)	0.0064 (8)
C13	0.0203 (11)	0.0152 (10)	0.0394 (13)	−0.0030 (8)	−0.0049 (9)	0.0101 (9)
C14	0.0394 (14)	0.0256 (12)	0.0244 (11)	−0.0042 (10)	−0.0035 (10)	0.0107 (9)
C15	0.0389 (13)	0.0297 (12)	0.0243 (11)	−0.0027 (10)	0.0040 (10)	0.0085 (9)
C16	0.0292 (11)	0.0245 (11)	0.0241 (11)	−0.0009 (9)	0.0040 (9)	0.0067 (9)
N12	0.0293 (11)	0.0340 (11)	0.0355 (12)	0.0056 (9)	0.0020 (9)	0.0109 (9)
N21	0.0200 (9)	0.0183 (8)	0.0205 (8)	0.0010 (7)	0.0030 (7)	0.0052 (7)
C22	0.0225 (11)	0.0190 (10)	0.0237 (10)	−0.0005 (8)	0.0030 (8)	0.0056 (8)
C23	0.0243 (11)	0.0242 (11)	0.0246 (11)	0.0030 (9)	0.0073 (9)	0.0080 (9)
C24	0.0329 (12)	0.0168 (10)	0.0284 (11)	0.0022 (9)	0.0084 (10)	0.0042 (9)
C25	0.0258 (11)	0.0224 (11)	0.0277 (11)	−0.0035 (9)	0.0019 (9)	0.0054 (9)
C26	0.0216 (10)	0.0230 (11)	0.0247 (11)	−0.0003 (8)	0.0017 (9)	0.0055 (9)
N22	0.0245 (11)	0.0251 (11)	0.0522 (14)	0.0050 (9)	0.0060 (10)	0.0062 (10)
O1M	0.0173 (7)	0.0218 (7)	0.0205 (7)	0.0029 (6)	0.0031 (6)	0.0060 (6)
C1M	0.0214 (11)	0.0380 (13)	0.0333 (12)	0.0055 (10)	0.0088 (10)	0.0047 (10)

Geometric parameters (Å, º)

Co1—N11	2.1070 (16)	C14—H14	0.9300
Co1—O1M	2.1466 (15)	C15—C16	1.386 (3)
Co1—N21	2.1470 (17)	C15—H15	0.9300
Co1—O1	2.1662 (13)	C16—H16	0.9300
Co1—O2	2.1887 (14)	N12—H12A	0.98 (3)
Co1—Cl1	2.3793 (5)	N12—H12B	1.04 (3)
O1—C1	1.268 (2)	N21—C22	1.334 (3)
O2—C1	1.264 (2)	N21—C26	1.341 (3)
C1—C2	1.508 (3)	C22—C23	1.396 (3)
C2—C3	1.529 (3)	C22—H22	0.9300
C2—H2A	0.9700	C23—N22	1.371 (3)
C2—H2B	0.9700	C23—C24	1.397 (3)
C3—C4	1.510 (3)	C24—C25	1.380 (3)
C3—H3A	0.9700	C24—H24	0.9300
C3—H3B	0.9700	C25—C26	1.372 (3)
C4—C4^i	1.516 (5)	C25—H25	0.9300
C4—H4A	0.9700	C26—H26	0.9300
C4—H4B	0.9700	N22—H22A	0.83 (3)
N11—C12	1.334 (3)	N22—H22B	0.85 (3)
N11—C16	1.348 (3)	O1M—C1M	1.430 (3)
C12—C13	1.411 (3)	O1M—H1M	0.75 (3)
C12—H12	0.9300	C1M—H1A	0.9600
C13—N12	1.371 (3)	C1M—H1B	0.9600
C13—C14	1.390 (3)	C1M—H1C	0.9600
C14—C15	1.365 (3)
N11—Co1—O1M	95.08 (6)	N12—C13—C12	120.5 (2)
N11—Co1—N21	90.75 (6)	C14—C13—C12	117.7 (2)
O1M—Co1—N21	174.16 (6)	C15—C14—C13	119.9 (2)
N11—Co1—O1	154.37 (6)	C15—C14—H14	120.1
O1M—Co1—O1	88.17 (5)	C13—C14—H14	120.1
N21—Co1—O1	86.44 (6)	C14—C15—C16	119.2 (2)
N11—Co1—O2	94.26 (6)	C14—C15—H15	120.4
O1M—Co1—O2	90.97 (6)	C16—C15—H15	120.4
N21—Co1—O2	88.29 (6)	N11—C16—C15	122.2 (2)
O1—Co1—O2	60.21 (5)	N11—C16—H16	118.9
N11—Co1—Cl1	99.58 (5)	C15—C16—H16	118.9
O1M—Co1—Cl1	85.16 (4)	C13—N12—H12A	110.8 (18)
N21—Co1—Cl1	94.17 (5)	C13—N12—H12B	115.0 (18)
O1—Co1—Cl1	106.03 (4)	H12A—N12—H12B	116 (3)
O2—Co1—Cl1	165.89 (4)	C22—N21—C26	118.41 (18)
C1—O1—Co1	90.65 (11)	C22—N21—Co1	122.13 (13)
C1—O2—Co1	89.72 (12)	C26—N21—Co1	118.80 (14)
O2—C1—O1	119.22 (18)	N21—C22—C23	123.50 (19)
O2—C1—C2	120.82 (18)	N21—C22—H22	118.2
O1—C1—C2	119.96 (18)	C23—C22—H22	118.2
C1—C2—C3	113.29 (18)	N22—C23—C22	121.1 (2)
C1—C2—H2A	108.9	N22—C23—C24	121.7 (2)
C3—C2—H2A	108.9	C22—C23—C24	117.09 (19)
C1—C2—H2B	108.9	C25—C24—C23	119.0 (2)
C3—C2—H2B	108.9	C25—C24—H24	120.5
H2A—C2—H2B	107.7	C23—C24—H24	120.5
C4—C3—C2	114.22 (19)	C26—C25—C24	119.9 (2)
C4—C3—H3A	108.7	C26—C25—H25	120.0
C2—C3—H3A	108.7	C24—C25—H25	120.0
C4—C3—H3B	108.7	N21—C26—C25	122.0 (2)
C2—C3—H3B	108.7	N21—C26—H26	119.0
H3A—C3—H3B	107.6	C25—C26—H26	119.0
C3—C4—C4^i	114.8 (2)	C23—N22—H22A	116 (2)
C3—C4—H4A	108.6	C23—N22—H22B	118 (2)
C4^i—C4—H4A	108.6	H22A—N22—H22B	120 (3)
C3—C4—H4B	108.6	C1M—O1M—Co1	125.62 (13)
C4^i—C4—H4B	108.6	C1M—O1M—H1M	110 (2)
H4A—C4—H4B	107.5	Co1—O1M—H1M	104 (2)
C12—N11—C16	118.68 (18)	O1M—C1M—H1A	109.5
C12—N11—Co1	122.06 (14)	O1M—C1M—H1B	109.5
C16—N11—Co1	119.15 (14)	H1A—C1M—H1B	109.5
N11—C12—C13	122.3 (2)	O1M—C1M—H1C	109.5
N11—C12—H12	118.9	H1A—C1M—H1C	109.5
C13—C12—H12	118.9	H1B—C1M—H1C	109.5
N12—C13—C14	121.7 (2)

Symmetry code: (i) −x+2, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1M—H1M···O1^ii	0.75 (3)	1.98 (3)	2.683 (2)	156 (3)
N22—H22A···O2^iii	0.83 (3)	2.13 (3)	2.952 (3)	175 (3)
N12—H12A···Cl1^iv	0.98 (3)	2.41 (3)	3.375 (2)	169 (3)
N12—H12B···Cl1^v	1.04 (3)	2.40 (3)	3.430 (2)	169 (3)

Symmetry codes: (ii) −x+2, −y+1, −z+1; (iii) x+1, y, z; (iv) x−1, y, z; (v) −x+1, −y+1, −z.