Preparation and nuclear magnetic resonance characterization of N-bonded complexes of platinum(II) with phosphorus-nitrogen rings containing three-coordinate chalcogens: X-ray structure of [PtCl2(PEt3)]2(Ph4P2N4Se2Et2)

Article abstract of DOI:10.1139/v93-227

The reaction of 1,5-Ph₄P₂N₄S₂Ph₂ with [PtCl₂(PEt₃)]₂ in chloroform at 60°C produces the 1:1 adduct trans-PtCl₂(PEt₃)(Ph₄P₂N₄S₂Ph₂) in which the platinum is attached to a nitrogen atom on the basis of ³¹P nmr spectroscopy. By contrast, the corresponding reactions of 1,5-Ph₄P₂N₄Se₂R₂ (R = Me, Et, Ph) produce the 2:1 adducts [PtCl₂(PEt₃)]₂(Ph₄P₂N₄Se₂R₂) (7a, R = Me; 7b, R = Et; 7c, R = Ph) which have been characterized by ¹H, ³¹P and ⁷⁷Se nmr spectroscopy and, in the case of 7b, by X-ray crystallography. Crystals of 7b are monoclinic, space group C2/c, with a = 27.803(7) A, b = 12.378(7) A, c = 15.752(8) A, β = 115.49(2)°, V = 4893(3) A³, and Z = 4. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at R = 0.037 and R(w) = 0.022. The platinum centres in 7b are attached to distal nitrogen atoms of the disordered P₂N₄Se₂ ring. The reaction of the six-membered ring Ph₄P₂N₃SPh with [PtCl₂(PEt₃)]₂ in dichloromethane at 23°C occurs in a regiospecific manner to give the 1:1 adduct PtCl₂(PEt₃)(Ph₄P₂N₃SPh) in which, on the basis of ³¹P nmr spectroscopy, the platinum is coordinated to a nitrogen atom between phosphorus and sulfur.