Macrocyclic polyphosphane ligands. Cobalt(II) and nickel(II) complexes of (4RS, 7RS, 13RS, 16RS)-tetraphenyl-1,10-dithia-4,7,13,16-tetraphosphacyclo-octadecane and crystal structure of the nickel dibromide complex

Abstract

The chiral configuration of the title diastereoisomer, δ-L¹, has been ascertained by the X-ray crystal structure of its nickel complex [Ni(δ-L¹)]Br₂·5.5H₂O. The complex crystallises in the monoclinic space group P2₁/n with a= 17.375(5), b= 15.047(5), c= 16.122(5)Å, β= 90.33(4)°, and Z= 4. Least-squares refinement gives R= 0.066 for the 1 881 observed reflections. The nickel atom is five-co-ordinated by one sulphur and four phosphorus atoms of the macrocycle according to a distorted trigonal-bipyramidal geometry. The stereochemistry of some cobalt(II) and nickel(II) complexes of this ligand are investigated in the solution and in the solid state by electronic spectroscopy.