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Abstract
Red specimens of [Co[(NH)4Ox]2(S4O6)·H2O (I), Co2S4O15N8C4H26, crystallize in the monoclinic space group P21/c. The cell is defined by the following constants: a = 7.7601(7), b = 10.079(1), c = 29.865(3) Å, β = 90.914(8)°, V = 2335.59 Å3, d (z = 4; M.W. = 672.42 gm – mole−1) = 1.912 gm-cm−3. A total of 3430 data was collected in the interval 4.0° ≤ 2Θ ≤ 50.0° of which 1915 were unique and had intensities greater than 3σ(I). The data were corrected for absorption using empirical Psi scan curves (five reflections, μ = 18.395 cm−1); the relative transmission coefficients ranged from 0.9697 to 0.9988. The final values of the discrepancy parameters were R(F) = 0.0388 and Rw(F) = 0.0484.
The axial Col-N distances are 1.950(4) and 1.936(4) Å, while those associated with Co2 are 1.949(5) and 1.952(4) Å. Col-N distances in the equatorial plane are 1.942(3) and 1.918(4) Å, respectively. For the second cation, the equatorial Co-N distances are 1.910(4) and 1.938(4) Å. Thus, the feature of short and long Co-N distances is consistent for both cations. The Col-O distances are 1.906(3) and 1.896(3) Å, while those for Co2 are 1.914(3) and 1.899(4) Å, showing a distortion in these bonds which we have observed in earlier studies of bidentate oxalates and carbonates of Co(III) amines, and which seem to parallel the inequivalence of the Co-N bonds.
The stereochemistry of the tetrathionate anion is as follows: (a) the outer S-S(O3) bonds are 2.127(2) and 2.120(2) Å in length, while the central S-S distance is 2.014(2) Å (b) the S-O distances range from 1.430(4) to 1.461(4) Å with mean value of 1.445(4) Å. The S1-S2-S3-S4 torsional angle is 97.8°, which is a few degrees larger than the value found in its alkali salts - a result, no doubt, of the hydrogen bonding to the amines of the two cations.
The two independent cations are linked to one another by hydrogen-bonded interactions with the O3S - fragments of the tetrathionates in such a way that there are approximate (non-crystallographic) mirror planes perpendicular to all three axes. We suggest this is the reason why this substance crystallizes via the racemic pathway.