Preparation and P-31 Nmr Characterization of N-Bonded Complexes of Platinum(ii) with a Phosphadithiatriazine - X-Ray Structure of Trans-Ptcl2(pet3)(eta-1-N-Ph2ps2n3)

by Chivers, Tristram; Hilts, Robert W.; Krouse, Ian H.; Cordes, A. Wallace; Hallford, Randal L.; Scott, Syrona Renae Horton

The reaction of Ph2PS2N3 with [Pt2(mu-Cl)2(PEt3)4][BF4]2 or [PtCl2(PEt3)]2 in dichloromethane at 23-degrees-C produces the 1:1 adducts cis-[PtCl(PEt3)2(Ph2PS2N3)][BF4], 3, and trans-[PtC12(PEt3)(Ph2PS3N2)], 4, respectively, in good yields. The P-31 NMR data for 3 and 4 indicate that (i) the platinum is attached to a nitrogen atom adjacent to phosphorus in both these adducts, (ii) the PEt3 ligands in 3 are in mutually cis positions, and (iii) the PEt3 ligand in 4 is trans to the heterocyclic nitrogen. These structural features were confirmed by an X-ray analysis of 4. Crystals of 4 are monoclinic, space group P2(1)/c, with a = 14.920(3) angstrom, b = 8.966(5) angstrom, c = 19.103(5) angstrom, beta = 109.32(2)-degrees, V = 2411.6(16) angstrom3 , and Z = 4. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at R = 0.050 and R(w) = 0.053. The Pt-N bond length is 2.122(15) angstrom and the coordinated nitrogen atom is lifted ca. 0.63(2) angstrom out of the plane containing the other heterocyclic ring atoms. The attachment of a platinum(II) centre to the PN3S2 ring perturbs the S-N bond lengths significantly. The S-N distance involving the coordinated nitrogen is 1.672(16) angstrom, while the other S-N distances are 1.631(19), 1.555(19), and 1.562(19) angstrom, indicative of a localized sulfur diimide (-N=S-N-) structure. The UV-visible spectra of 3 and 4 in CH2Cl2 exhibit absorption bands at 514 and 528 nm, respectively, but dissociation of these adducts to give the free ligand Ph2PS2N3 occurs readily in dilute solution.

Canadian Journal of Chemistry-Revue Canadienne de Chimie
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1480-3291; 0008-4042