Pseudohalides complex hydrides

The hydride complexes [MoH(CO)2(chel)2]+ (chel = variety of chelating diphosphines and arsines) are prepared by protonation of the parent Mo° dicarbonyls and appear to have a monocapped octahedral structure in solution, with the fluxional hydride moving around the possible capping positions. This process has been extensively studied by NMR.65 A number of other cationic seven-coordinate analogues [MoX(CO)2(chel)2]+ (X = halide or pseudohalide chel = chelating ligand usually phosphine or arsine) are also known (Table 5).la... 

This report deals with those publications from 2000 that described advances in metal carbonyl chemistry. This includes those studies that explore the chemistry of the simple metal carbonyls themselves [such as Mo(CO)6 and Fe(CO)s], metal carbonyl halides [e.gf. Mn(CO)sBr], pseudohalides le.g. Mn(CO)5(CN)] and hydrides [e.g. Re(CO)5H], This section is not restricted to mononuclear species. Indeed, carbonyl complexes containing more than one metal atom have formed a large part of this report for many years and the percentage of polynuclear carbonyl complexes is, if anything, increasing. 

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