Hydride-phosphine complexes

Scheme 7.4 Formation of surface rhodium siloxide complexes containing phosphine and hydride ligands.

Mdssbauer spectra of bonding and structure in, 15 184-187 reactions with diborane, 16 213 stabilization of, 5 17, 18-19 cyanates, 17 297, 298 cyanide complexes of, 8 143-144 cyclometallated bipyridine complex, 30 76 diazene complexes, 27 231-232 dinitrogen complexes, 27 215, 217 diphosphine complexes of, 14 208-219 dithiocarbamates, 23 253-254 -1,2-dithiolene complexes, 22 323-327 hydrogen bonding, 22 327 halide complexes with phosphine, etc., 6 25 hexaflouride, structure, 27 104 hydride complexes, 20 235, 248-281, see also Transition metal-hydride complexes... 

In a study which is relevant to the mechanism of hydrolysis of phosphonium salts, Glaser and Streitwieser297 studied the ions H4PO- and H3PFO- and their derivatives with Li +, NH4 and HF at the 6-31G level augmented by diffuse functions. They found that the structures of the anions are those of a hydride or fluoride ion solvated by or complexed with phosphine oxide, rather than phosphoranes297. A very important point is that earlier studies with diffuse functions yielded the pentacoordinated phosphoranes which they judged297 to be computational artifacts of the small basis set. 

Several complex hydrides have been prepared, such as AgBH4 these were all thermally unstable.383 More stable complexes were obtained with substituted boranes when isolated as phosphine derivatives.386-388... 

Phosphines and their derivatives are known to be very useful ligands toward transition metals and a variety of complexes with phosphine as a ligand have been prepared for all kinds of transition metals. If one of the substituents on a coordinating tertiary phosphorus compound is abstracted as an anion, it would form a cationic phosphenium complex. Actually this strategy has been widely used, and halide, hydride, and alkoxide have been abstracted as an anion by an appropriate Lewis acid. An alternative method to prepare cationic phosphenium complexes is a direct reaction of a phosphenium cation with a transition metal complex having appropriate... 

Many phosphine-borane complexes Y3P BZ3 have been characterized. They include compouuds where Y = alkoxy, aUcyl, amino, halide, and hydride groups, and Z = alkyl, halide, and hydride. The stabilities of these complexes vary widely depending on the Lewis acidity and basicity of the boron and phosphorus moieties, respectively. The relative stabilities of Lewis acid-base complexes with BH3 are R3P > R3N > R3AS > R3Sb, but with BF3 the order is R3N > R3P > R3AS > RsSb. The stabihties of the borou halide complexes of phosphines follow the same order as the amine complexes BI3 > BBrs > BCI3 > BF3. 

Mo and W atoms play an important role in oxidative addition to C-H bonds. W activates linear and cyclic saturated hydrocarbons in the presence of PMe3, while Mo reacts with bidentate phosphine to give a Mo (hydride)phosphine complex ... 

The formation of Ag(I) and Au(I) hydrides at > lOOO C in H is confirmed by spectroscopic studies on the metal hydrides and deuterides in the vapor phase . Attempts to prepare an Au hydride-phosphine complex from H in solution fail, although one is almost certainly formed as an intermediate ... 

In the absence of strongly rr-bonding ligands such as tertiary phosphines, complex hydrides, e.g., [A1HJ and [BHJ react with Cu, Ag and Au halides to form metal-hydrogen compounds, usually of low thermal stability. Uncomplexed CuH is unstable, even at — 80 C. 

The induction period can be explained as the result of reactions a or /3. The first, proposed by Heck 89), requires that tetracarbonylnickel have basic properties, but this could not be proved. In fact, the protonation reaction of carbonyls and carbonyl derivatives has been studied by Wilkinson and co-workers 64) Ni(CO)4 does react with acids but, contrary to Fe(CO)5, gives no NMR signal—indicating the formation of a hydride. However, the basic properties of some systems have been recently shown in complexes with phosphines and arsines. The platinum (0) 39, 40) derivatives yield stable hydrides according to the following equilibria ... 

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