Trans effect hydride ligand

In the triazenido complex, there is a slight trans labilizing effect of the hydride over the carbonyl, as reflected in the trans Ru-N distances. This effect is much more pronounced in the amidinato complex because of the absence of disorder and perhaps because the four-membered ring has opened up so that atom N(2) is more nearly trans to the hydride ligand. 

Transfer of a hydride to another ligand on substitution is also possible (equation 59). Alternatively, substitution reactions can occur without loss of the H ligand. This is common where only one H is present (equation 60). The presence of the coordinated hydrogen can even encourage such reactions by its high trans effect and perhaps even by transfer to a CO (or related ligand, where one is present) to give a transient formyl and an open site (equation 61). 

The latter is outside the scope of organometallic chemistry, but within the first two topics the work involved three main themes olefin and acetylene complexes, alkyl and aryl complexes, and hydride complexes. As continuous subsidiary themes throughout ran the complex chemistry of tertiary phosphines and such ligands, the nature of the trans effect, and the nature of the coordinate bond. All the work from 1947 to 1969 was carried out in the Butterwick Research Laboratories, later renamed Akers Research Laboratories, of Imperial Chemical Industries Ltd., and I am indebted to that Company and particularly to Mr. R. M. Winter, the Company s Controller of Research, and Sir Wallace Akers, its Director of Research, who in 1947, made available to me the opportunity to develop my research in my own way, in those laboratories. 

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