Tertiary phosphine abstraction from a platinum(II) coordination complex with SeCN −: Crystal and molecular structures of Se [dbnd]PTA and [Se [dbnd]PTA-Me]I · CH 3OH

Abstract

Reacting [PtCl(PTA) 3]Cl(PTA = 1,3,5-triaza-7-phosphatricyclo[3.3.1.1 3,7]decane) with KSeCN in aqueous or MeOH medium results in the abstraction of the PTA ligands to yield Se PTA. 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[3.3.1.1 3,7]decane iodide), reacts accordingly with KSeCN, albeit significantly slower. The crystal structure of Se PTA, 1, and [Se PTA-Me]I · CH 3OH, 2, revealed P Se bond distances of 2.0991(19) and 2.100(2) Å, respectively. The first order phosphorous selenium coupling constants, 1 J P–Se (D 2O), of 722 and 788 Hz for Se PTA and [Se PTA-Me]I, respectively, indicates the latter is significantly less electron rich.