Construction of Organoplatinum(II) Complexes by a Tripod Phosphine Ligand:A Joint Experimental and Computational Investigation

The chemistry of ۱,۱,۱-tris(diphenylphosphino)methane (tppm) as a ligand is less explored[۱]in comparison with bis(diphenylphosphino)methane (dppm)[۲], and only a handful of studies aredocumented in the literature. This ligand opens up an opportunity for systematic investigation ofthe steric and electronic effects on chemical and physical properties, in which, by purposefulvariation of the substituent groups on phosphorus, a wide array of properties can be "fine-tuned"[۳].Taking this considerable potential into account, two organoplatinum(II) complexes [PtR۲(tppm)] (R= Me, ۱, p-MeC۶H۴, ۲) were synthesized starting from the well-known precursor [PtR۲(SMe۲)۲] (R= Me, A, p-MeC۶H۴, B) through ligand substitution in acetone. The structures of the obtained Pt(II)complexes were characterized by NMR spectroscopy, HR ESI-MS(+), and X-ray crystallography(Figure ۱). In these Pt(II) complexes, the tppm ligand is bound to the Pt center via monodentatechelatingmode, rendering one of the tppm's P atoms uncoordinated.In the following, computationalcalculations using density functional theory (DFT) and time-dependent DFT (TD-DFT) werecarried out in order to gain deep insight into experimental observations.Figure ۱. Crystal structure of ۲.