Coligand effects on bonding mode. Synthesis and properties of (diallylmalonato)platinum(II) complexes of P vs. N donating ligand

Abstract

The reaction of cis-[Pt-II(OH)(2)A(2)] (A = triethylphosphine (PEt3); A(2) = tetrahydro-4H-pyran-4,4-dimethanamine (hpda)) with diallylmalonic acid in aqueous solution affords cis-[Pt(dam)A(2)] (dam = diallylmalonate). The bending mode of the dam is dependent upon the donation effect of the phosphine vs the nitrogen coligand. The crystal structure of cis-[Pt(dam)(PEt3)(2)] (C21H40O4P2Pt . H2O: monoclinic P2(1)/c, a = 13.918(2), b = 12.464(1), c = 15.737(1) Angstrom, beta = 107.097(8)degrees, V = 2609.4(4) Angstrom(3), Z = 4, R = 0.033) discloses that the dam is bonded to the platinum atom in a (kappa(2)O(3))-mode (Pt-O = 2.057(4), 2.061(4) Angstrom) with two phosphine ligands in the cis position. In contrast, for cis-[Pt(dam)(hpda)] (C16H16N2O5Pt . 4.5H(2)O: monoclinic C2/c, a = 28.250(3), b = 11.169(1), c = 13.368(4) Angstrom, beta = 94.16(1)degrees, V = 4207(1) Angstrom(3), Z = 8, R = 0.0293), the dam ligand is chelated to the platinum(II) ion in a (kappa O,eta(2)-C,C)-mode (Pt-O = 2.004(4) Angstrom; Pt-C = 2.089(6), 2.101(6) Angstrom) in the solid state. cis-[Pt(kappa(2)O(3)-dam)(PEt3)(2)] easily reacts with KBr pellet matrix for IR measurements while cis-[Pt(kappa O,eta(2)-C,C-dam)(hpda)] is inert in the pellet. In solution, however, the structure of cis[Pt(kappa(2)O(3)-dam)(hpda)]. [Pt(kappa(2)O(3)-dam)(PEt3)(2)] is locked, whereas cis-[Pt(kappa O,eta(2)-C,C-dam)(hpda)] can be isomerized to cis-[Pt(kappa(2)O(3)-dam)(hpda)].