Metal carbonyl-dihydrogen reactions

Photochemical Reactions of Metal Carbonyls with Dihydrogen... 

The reactions between unsaturated metal carbonyls and dihydrogen have attracted much interest. Sweany discovered that a reversible interconversion between Fe(CO)4 and Fe(CO)4H2 could be initiated by selective photolysis ... 

The relationship between metal carbonyl hydrides and dihydrogen complexes of metal carbonyl derivatives has been further explored.The interactions of d ML5 fragments with H2 have been studied by EHMO methods,and the structures and some reactions of n -H2 complexes of Cr, Mo, W, Fe and Co carbonyl derivatives examined.Intramolecular ligand rearrangements in [M(C0)5H] anions (M = Cr or Mo) have been investigated using variable temperature n.m.r. A twist mechanism that provides a pathway for intramolecular axial-equatorial CO exchange is favoured.The catalytic role of these... 

By contrast, the reactions of the P-diketiminato-stabUized gaUium dihydiide HC(MeCDippN)2 GaH2 with a range of mono- and dinuclear metal carbonyl reagents demonstrate, perhaps more clearly than any other systems, the propensity for gallanes to lose dihydrogen and form... 

The direct reductive amination (DRA) is a useful method for the synthesis of amino derivatives from carbonyl compounds, amines, and H2. Precious-metal (Ru [130-132], Rh [133-137], Ir [138-142], Pd [143]) catalyzed reactions are well known to date. The first Fe-catalyzed DRA reaction was reported by Bhanage and coworkers in 2008 (Scheme 42) [144]. Although the reaction conditions are not mild (high temperature, moderate H2 pressure), the hydrogenation of imines and/or enam-ines, which are generated by reaction of organic carbonyl compounds with amines, produces various substituted aryl and/or alkyl amines. A dihydrogen or dihydride iron complex was proposed as a reactive intermediate within the catalytic cycle. 

FTIR has been mainly used to obtain structural details of films and to monitor intercalation of metal ions into the film structure and the subsequent reactions of the films with dihydrogen chalcogenides. Both transmission (FTIR-T) and reflection-absorbance (FTIR-RA) modes have been utilized. For the most part these studies have involved films of fatty acids with divalent metal ions. The key features of the FTIR spectra of these films include the asymmetric and symmetric stretching modes of the carboxylate group vs(C02-) and va(C02 ), associated with the M2+/carboxylate complex, and the carbonyl stretching mode v(C=0) of the proton-ated fatty acid. The disappearance of the v(C02 ) (1500-1600 cm-1) and appearance of the v(C=0) bands (—1700 cm-1), concurrent with the formation of the metal chalcogenide and regeneration of the fatty acid, have been used to evaluate... 

Following these, this method has been widely used Table IV lists more recent applications. Only those reactions that evolve dihydrogen are included here. Oxidative addition reactions leading to metal hydride derivatives are included in Table V, while processes involving elimination of dihydrogen between hydridosilanes and metal hydride derivatives containing no carbonyl groups are deferred until Section H,G,1. 

---