Synthesis and structure of [Pt2(?-H)(?-CHCH2Ph)(diphos)2][BF4]

Cationic dinuclear platinum and palladium complexes with bridging hydrogermylene and hydrido ligands

Hydride-abstraction reactions of hydrido(dihydrogermyl) complexes [MH(GeH2Trip)(dcpe)] [M = Pt, Pd, Trip = 9-triptycyl, dcpe = 1,2-bis(dicyclohexylphosphino)ethane] with B(C6F5)3 led to the unexpected formation of new cationic (μ-germyl)(μ-hydrido) dinuclear platinum and palladium complexes, [{M(dcpe)}2(μ-GeHTrip)(μ-H)](+).

Rational design of porous coordination polymers based on bis(phosphine)MCl2 complexes that exhibit high-temperature H2 sorption and chemical reactivity

MCl2 complexes of a new p-carboxylated 1,2-bis(diphenylphosphino)benzene ligand are effectively utilized as tetratopic building blocks to prepare isostructural porous coordination polymers with accessible reactive metal sites (M = Pd, Pt). The crystalline materials exhibit unusual and fully reversible H2 sorption at 150 °C. Post-synthetic reactivity is also possible, in which Pt-Cl bonds can be activated to provide organometallic species in the pores.

Reaction Chemistry of Complexes Containing PtH, PtSH, or PtS Fragments: From Their Apparent Simplicity to the Maze of Reactions Underlying Their Interconversion

The relevance of platinum in the reaction of thiophene and derivatives with homogeneous transition-metal complexes as models for hydrodesulfurization has led us to the study of the reaction chemistry of complexes containing Pt--H, Pt--SH, and Pt--S fragments. Exploration of the reactions triggered by addition of controlled amounts of Na2S or NaSH to [Pt2(H)2(mu-H)(dppp)2]ClO4 (1) has provided evidence of the formation of complexes [Pt2(mu-H)(mu-S)(dppp)2]ClO4 (2), [Pt(H)(SH)(dppp)] (3), [Pt2(mu-S)2(dppp)2] (4), [Pt2(mu-S)(dppp)2] (5) and [Pt(SH)2(dppp)], in which dppp denotes 1,3-bis(diphenylphosphanyl)propane. Consequently, complexes 1, 2, and 5 as well as the already reported 3, 4, and [Pt(SH)2(dppp)] have been obtained and fully characterized spectroscopically. Also the crystal structures of 1 and 2 have been solved. Complexes 1-5 constitute the main framework of the network of reactions that account for the evolution of 1 under various experimental conditions as shown in Scheme 1. Apparently, this network has complexes 2 and 4 as dead-ends. However, their reciprocal interconversion by means of the replacement of one bridging hydride or sulfide ligand in the respective {Pt(mu-H)(mu-S)Pt} and {Pt(mu-S)2Pt} cores enables the closure of the reaction cycle involving complexes 1-5. Theoretical calculations support the existence of the undetected intermediates proposed for conversion from 1 to 2 and from 3 to 2 and also account for the fluxional behavior of 1 in solution. The intermediates proposed are consistent with the experimental results obtained in comparable reactions carried out with labeled reagents, which have provided evidence that complex 1 is the source of the hydride ligands in complexes 2 and 3. Overall, our results show the strong dependence on the experimental conditions for the formation of complexes 1-5 as well as for their further conversion in solution.

Multinuclear (1H,31P and195Pt) NMR study and dynamical analysis of binuclear µ-hydrido µ-carbonyl Pt(i) cations with chelating diphosphines

The dynamic behaviour of the binuclear mu-hydrido mu-carbonyl cations with chelating diphosphines, [Pt2(P-P)2(mu-H)(mu-CO)]+ [P-P = dppe, 1, dppp, 2, and dppb, 3] have been investigated by multinuclear (1H, 31P and 195Pt) variable temperature NMR spectroscopy. The 195Pt and 1H results are consistent with intramolecular mutual exchange of the P atoms with respect to the bridging ligands in all of the complexes 1-3. A detailed dynamical analysis carried out on complexes 2 and 3 shows that the dynamical process exchanges the P atoms within a single diphosphino ligand, and excludes the simultaneous P atom exchange in both ligands. The bite of the diphosphino ligands affects the rate of this process in the order 3 > 2 > 1. The process follows an activation law with deltaH++ = 67 and 60 kJ mol(-1) for 2 and 3, respectively, so that P-Pt bond breaking should not be involved. The positive activation entropy (17-19 J K(-1) mol(-1)) hints at a mechanism where the intermediate(s) have a less ordered structure than that of the stable complex. In accordance with the NMR results, two reactivity experiments provided further evidence of the intramolecular nature of the observed dynamics and exclude any equilibration path via Pt-P and/or Pt-Pt bond breaking. On these grounds, a mechanism involving rotation about a Pt-Pt bond could be proposed.