Crystal-Structures of cis-(N-Base)Chlorobis-(Ethane-1,2-Diamine)Cobalt(III) Dichloride (N-Base = Ammonia, Pyridine)

Abstract

The crystal structures of the two title compounds, cis-[Co(en)₂(NH₃) Cl ] Cl₂, (1), and cis-[Co(en)₂( py ) Cl ]Cl₂.H₂O, (2), have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by full-matrix least-squares techniques to residuals of 0.025 and 0.036 for 1744 and 3243 independent 'observed' reflections. Crystals of (1) and (2) are monoclinic, P2₁/c, Z = 4. For (1), a 7.499(1), b 11.986(2), c 14.325(3)Ǻ, β 111.45(1)°; for (2), a 7.617(2), b 12.866(3), c 16.561(5), β 97.33(2)°. Both complexes are racemates with cation conformations Δ( δ,λ ), (1), and Δ( λ,λ ), (2). The structure determinations suggest that variations in the rate of base hydrolysis of these complexes and their imidazole analogue may be correlated with the degree of steric crowding associated with the introduction of the monodentate nitrogen base into the coordination sphere.