Tertiary phosphine abstraction from a platinum(II) coordination complex with SeCN−: Crystal and molecular structures of Sedouble bond; length as m-dashPTA and [Sedouble bond; length as m-dashPTA-Me]I · CH3OH

Reacting [PtCl(PTA)3]Cl(PTA = 1,3,5-triaza-7-phosphatricyclo[3.3.1.13,7]decane) with KSeCN in aqueous or MeOH medium results in the abstraction of the PTA ligands to yield Sedouble bond; length as m-dashPTA. The reaction also proceeds quantitatively by direct reaction of PTA and KSeCN in water or methanol. The methylated PTA ligand, [PTA-Me]I (1-methyl-1-azonia-3,5-diaza-7-phosphatricyclo[3.3.1.13,7]decane iodide), reacts accordingly with KSeCN, albeit significantly slower. The crystal structure of Sedouble bond; length as m-dashPTA, 1, and [Sedouble bond; length as m-dashPTA-Me]I · CH3OH, 2, revealed Pdouble bond; length as m-dashSe bond distances of 2.0991(19) and 2.100(2) Å, respectively. The first order phosphorous selenium coupling constants, 1JP–Se (D2O), of 722 and 788 Hz for Sedouble bond; length as m-dashPTA and [Sedouble bond; length as m-dashPTA-Me]I, respectively, indicates the latter is significantly less electron rich.