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

Abstract

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.

Steric Effect of a Phosphane Ligand on the Equilibrium of Ge–Ge Bond Formation at a Platinum Center

“…The Pt–P and Pt–Ge bond lengths are similar to those of previously reported germylplatinum complexes 8–12. The P–Pt–P bond angles are 85.44(7)° for 2 and 85.75(5)° for 3 , which are smaller than those of the PPh 3 analogues,8,9 because the steric repulsion between the substituents on the two phosphorus atoms is reduced. The two aryl groups on the germanium atoms in 2 are arranged in propeller form, while those in 3 are in twisted‐parallel form.…”

Si–H Bond Activation of a Primary Silane with a Pt(0) Complex: Synthesis and Structures of Mononuclear (Hydrido)(dihydrosilyl) Platinum(II) Complexes

“…The SiH 2 resonance appeared as a multiplet at δ = 4.68 ppm. The 31 P{ 1 H} NMR spectrum of 2 exhibited two doublets ( 2 J P-P = 15 Hz) at δ = 33.8 and 34.5 with 195 Pt-31 P coupling constants, 2183 and 1963 Hz, which were assigned to the phosphorus atoms lying trans to the hydrido and dihydrosilyl ligands, respectively, in agreement with the NMR data for reported germanium congener [cis-PtH(GeH 2 Trip)(PPh 3 ) 2 ] [δ = 31.2 ( 1 J Pt-P = 2317 Hz) and 31.6 ( 1 J Pt-P = 2252 Hz)] [37]. The silicon atom of 2 gave rise to a resonance around δ = −40.6 with splitting due to 31 P- 29 Si couplings ( 2 J P(trans)-Si = 161, 2 J P(cis)-Si = 15 Hz) and 195 Pt satellites ( 1 J Pt-Si = 1220 Hz) in the 29 Si{ 1 H} NMR spectrum.…”

“…[36]. Meanwhile, we succeeded in the first isolation of a series of hydrido(dihydrogermyl) platinum(II) complexes [PtH(GeH2Trip)(L)] (Trip = 9-triptycyl) using a bulky substituent, 9-triptycyl group [37]. In addition, we reported the first syntheses and structural characterizations of hydrido palladium(II) complexes with a dihydrosilylor dihydrogermyl ligand, [PdH(EH2Trip)(dcpe)] (E = Si, Ge) [38].…”

Synthesis, Structure, and Reactivity of a Mononuclear η2‐(Ge–H)palladium(0) Complex Bearing a PGeP‐Pincer‐Type Germyl Ligand: Reactivity Differences between Silicon and Germanium

“…Braddock‐Wilking, Osakada, and Mochida reported preparation and structure of germyl‐bridged diplatinum or dipalladium complexes having two M–H–Ge three‐center–two‐electron bonds (Figure ) . Regarding mononuclear complexes, no precedent of an η 2 ‐(Ge–H) group 10 metal complex has been reported although there are several examples of the formation of germylpalladium(II) or ‐platinum(II) complexes through oxidative addition of the Ge–H bond to zero valent Pd or Pt metals . It is conceivable that the weaker bond dissociation energy of a Ge–H σ‐bond than that of a Si–H bond facilitates oxidative addition from the η 2 ‐(Ge–H)M 0 intermediate .…”