Macrocyclic polyphosphane ligands. Cobalt(II) and nickel(II) complexes of the γ and ε diastereoisomers of 4,7,13,16-tetraphenyl-4,7,13,16-tetraphospha-1,10-dithiacyclo-octadecane(L1) and the crystal structure of [Co(ε-L1)][BPh4]2·EtOH

Abstract

The chiral configuration of the title diastereoisomer, ε-L¹, has been ascertained by the X-ray crystal-structure determination of its cobalt(II) complex [Co(ε-L¹)][BPh₄]₂·EtOH. The complex crystallises in the monoclinic space group P2₁/c, with a= 14.590(3), b= 13.004(3), c= 40.972(9)Å, β= 91.80(4)°, and Z= 4. Least-squares refinement gave R= 0.114 for 1 241 observed reflections. The cobalt atom is six-co-ordinated by two sulphur and four phosphorus atoms of the macrocycle forming a distorted cis-octahedral geometry. The nickel complexes are attributed a similar stereochemistry on the basis of their electronic spectra. The stereochemistry of the cobalt and nickel complexes of γ-L¹ has been investigated by electronic spectroscopy. The γ-L¹ isomer behaves as a quadridentate tetraphosphane ligand, the two sulphur atoms being unco-ordinated.