On the correlation between bond lengths, chemical shifts, and cone angles in octahedral cobaloximes containing P-donor ligands. Crystal structure of trans-chlorobis(dimethylglyoximato)(phosphite)cobalt(III) complexes with phosphite = P(OMe)₂Ph and P(OMe)Ph₂

The crystal structures of the title compounds, [CoCl(Hdmg)₂{P(OMe)₂Ph}] (1) and [CoCl(Hdmg)₂{P(OMe)Ph₂}] (2), are reported and discussed. Compound (1) crystallizes in the tetragonal system, space group I4₁/a, with unit-cell parameters a = 33.78(1), c = 8.421(6) Å, and Z = 16; (2) crystallizes in the orthorhombic system, space group Pbca, with unit-cell parameters a = 18.230(8), b = 15.725(7), c = 17.134(8) Å, and Z = 8. Both structures have been solved by Patterson and Fourier methods and refined by block-diagonal anisotropic least-squares methods to final R values of 0.030 for both compounds, using 1 359 (1) and 1 859 (2) independent reflections. The Co-Cl and Co-P bond lengths are 2.288(2) and 2.213(2) Å, in (1) and 2.290(1) and 2.242(1) Å in (2). The equatorial dimethylglyoximate ligands are nearly coplanar making dihedral angles of 2.3 and 0.9° in (1) and (2) respectively. Each unit of (1) clathrates 0.125 toluene molecules in large channels around a kind of tetrad rotatory inversion axis. Linear correlations between Co-P bond lengths, Tolman's cone angles, and ¹H n.m.r. chemical shifts are found and discussed in terms of the steric cis influence in the [CoX(Hdmg)₂(PR₃)] series.