Bridging nitrido groups

Iron centers that are more electron-deficient than iron(III) compounds are used for efficient and highly specific oxidation reactions in, for example, heme and nonheme enzymes [166-172]. Most iron(IV)-complexes found in biological reaction cycles possess terminal or bridging 0x0 groups as is known from a large number of structural and spectroscopic investigations. With the exception of iron(IV)-nitrido groups, nonoxo iron(IV) centers very rarely take part in such reactions. 

An essential feature of [Tc=N] + complexes is the Lewis basicity of the nitrido group, which can react with strong Lewis acids such as trivalent boron compounds. Recently the first nitrido bridges between technetium and boron were produced by an acid-base reaction between... 

An unusual dimeric complex has been synthesized by the reaction of [ReNCU] with TMSNPPha in acetonitrile. The rhenium atoms in [ Re(N)Cl(NPPh3C6H4) 2] (57), which possesses a Re—Re bond, are /i2-bridged via the A-atoms of the phosphoraneiminato ligands and the coordination spheres of the metal atoms are completed by nitrido and chloro ligands as well as by a Re—C bond to one phenyl group. 

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