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)

The reaction of 1,5-Ph 4 P 2 N 4 S 2 Ph 2 with [PtCl 2 CPEt 3 )] 2 in chloroform at 60 °C produces the 1:1 adduct trans-PtCl 2 (PEt 3 )(Ph 4 P 2 N 4 S 2 Ph 2 ) in which the platinum is attached to a nitrogen atom on the basis of 31 P nmr spectroscopy. By contrast, the corresponding reactions of 1,5-Ph 4 P 2 N 4 Se 2 R 2 (R = Me, Et, Ph) produce the 2:1 adducts [PtCl 2 (PEt 3 )] 2 (Ph 4 P 2 N 4 Se 2 R 2 ) ( 7 a, R = Me; 7 b, R = Et; 7 c, R = Ph) which have been characterized by 1 H, 31 P and 77 Se nmr spectroscopy and, in the case of 7 b, by X-ray crystallography. Crystals of 7 b are monoclinic, space group C2/c, with a = 27.803(7) Å, b = 12.378(7) Å, c = 15.752(8) Å, β = 115.49(2)°, V = 4893(3) Å 3 , 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 7 b are attached to distal nitrogen atoms of the disordered P 2 N 4 Se 2 ring. The reaction of the six-membered ring Ph 4 P 2 N 3 SPh with [PtCl 2 (PEt 3 )] 2 in dichloromethane at 23 °C occurs in a regiospecific manner to give the 1:1 adduct PtCl 2 (PEt 3 )(Ph 4 P 2 N 3 SPh) in which, on the basis of 31 P nmr spectroscopy, the platinum is coordinated to a nitrogen atom between phosphorus and sulfur.