Macrocyclic polyphosphane ligands. Cobalt(II) and nickel(II) complexes of 5RS,8RS,16RS,19RS-tetraphenyl-5,8,16,19-tetraphospha-1,12-dithiacyclodocosane (δ-L1) and the crystal structure of [Co(δ-L1)][BF4]2·0.5H2O

Abstract

The chiral configuration of the title ligand, δ-L¹, has been established by the X-ray crystal structure determination of its cobalt complex [Co(δ-L¹)][BF₄]₂·0.5H₂O. The compound crystallises in the orthorhombic space group Fddd, with a= 31.424(6), b= 24.633(5), c= 22.223(5)Å, and Z= 16. Least-squares refinement gave R= 0.080 for 1 695 observed reflections. The cobalt atom is low-spin and octahedrally co-ordinated by the macrocycle which adopts meridional configurations for the P(CH₂)₃S(CH₂)₃P moieties. The stereochemistry of some cobalt(II) and nickel(II) complexes of δ-L¹ with 1 : 1, 2 : 1, and 3 : 2 metal-to-ligand ratios is discussed.