Synthesis and Crystal Structures of the First Stable Mononuclear Dihydrogermyl(hydrido) Platinum(II) Complexes

The first stable dihydrogermyl(hydrido) platinum(II) complex cis-(Ph3P)2Pt(H)(GeH2Trip) (2) was synthesized by the oxidative addition reaction of an overcrowded trihydrogermane, TripGeH3 (1, Trip = 9-triptycyl), with (Ph3P)2Pt(η2-C2H4) in toluene. The reaction of 1 with (dppe)PtCl2 in the presence of NaBH4 afforded the corresponding hydrido complex (dppe)Pt(H)(GeH2Trip) (3) together with bis(germyl) platinum(II) complex (dppe)Pt(GeH2Trip)2 (4). In addition, the ligand exchange reaction of complex 2 with free Cy2PCH2CH2PCy2 in toluene resulted in the formation of (dcpe)Pt(H)(GeH2Trip) (5) in moderate yield. The structures of complexes 2−5 were fully determined on the basis of their NMR and IR spectra and elemental analyses. Moreover, the low-temperature X-ray crystallography of 2, 3, and 5 revealed that the platinum center has a distorted square-planar environment, probably due to the steric requirement of the cis-coordinated phosphine ligands and the bulky 9-triptycyl group on the germanium atom. Furthermore, the thermal rearrangement of bis(germyl) complex 4 in toluene at 60 °C gave digermyl(hydrido) complex (dppe)Pt(H)[Ge(HTrip)GeH2Trip] (6) in high yield without irreversible reductive elimination of tetrahydrodigermane.