Platinum hydride complexes structure

Hydride complexes of platinum have received considerable study since the preparation of PtHCl(PEt3)2- Spectroscopic studies by NMR techniques have been widely used because of the structural information which can be obtained from coupling constant data to Pt and other nuclei. Platinum is widely used as a heterogeneous catalyst, and vibrational studies on platinum hydride complexes have been useful for comparison of a hydrogen atom bonded to a single platinum with that bonded to a surface. Complexes of platinum have been used to catalyze hydrogenation, hydrosilylation and isomerization reactions with alkenes and alkynes, as well as H/D exchange reactions on alkanes. Hydride complexes are frequently proposed as intermediates in these reactions, and the pathways related to the known chemistry of hydride complexes. 

The great majority of platinum(I) complexes are binuclear with monofunctional or bifunctional bridging groups. However, there is also a series of unsupported dimers with the general structure shown in (12). These are generally stabilized by phosphine, carbonyl, and isocyanide ligands.17 Dimeric hydride complexes can have terminal or bridging hydrides and these are discussed above in Section 6.5.2.1.4. 

Section III.C A Hydrido(methyl)carbene Complex of Platinum(IV) (223) and Methyl(hydrido)platinum(IV) Complexes with Flexible Tridentate Nitrogen-Donor Ligands (224) are structurally related to the system shown in Scheme 13 and give additional information on how steric and electronic factors influence the stability of platinum(IV) methyl hydrides. 

The only example of a dihydride complex, lra i-[(Cy3P)2Pd(H)2], is formed by the reduction of bis(acetoacetonate)palladium(II) with triaUcylaluminum in the presence of PCy3 (Scheme 4). Its structure is deduced by analogy to the corresponding characterized platinum dihydride complex. The isolated product was reported to have an unusually low v(Pd—H) infrared band the authors ascribed this to the strong trans effect of the hydride ligands. However, the insolubility of the complex precludes any definitive NMR examination. 

Other Ligands.—Reactions of platinum(n) complexes PtHX(PR3>2 with azides, which give amido-complexes, may proceed by attack at the co-ordinated hydride. In Friedel-Crafts sulphination of Fe(butadiene)-(CO)s, attack is both at the metal and at the diene ligand, for an X-ray study has revealed that the structure of the intermediate is (49). ... 

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