Coordination with Transition Metals

The 0,0-diesters of dithiophosphoric adds, (RO)2P(S)SH, were first reported in 1908.120 Chemical interest in these compounds is threefold (a) their coordination with transition metal ions (b) their use as analytical reagents (c) the biological activity of both the ligands and their metal complexes. They have been used for the vulcanization of rubber121122 and as insecticides the latter activity is related to their enzyme-inhibition ability.123... 

The exceptional behaviour of heterounsaturated monomers of carbene-like structure, such as carbon monoxide and isocyanides, should be remembered here. Carbon monoxide readily undergoes copolymerisation with various unsaturated hydrocarbon monomers via coordination with transition metals [2]. By contrast, isocyanides are homopolymerised via coordination with a... 

Reactions of hetarenes coordinated with transition metals 93AHC (58)123. 

The products formed by hydrolysis are effective primary and secondary antioxidants. Polyfunctional antioxidants are formed during the application of cyclic arylene phosphites and various HD and chain breaking moieties which autosynergetically enhance their antioxidative activity. In addition to decomposing hydroperoxides, aromatic phosphites can also react with unsaturated (vinyl) groups in the polymer, coordinate with transition metal residues, help to preserve the hindered phenol, and prevent discoloration by reacting with quinoidal compounds. 

Allenylidenes could be considered as divalent radicals derived from allenes. In a similar way to vinylidenes, allenylidenes can be stabilized by coordination with transition metals and again ruthenium is one of the most widely used metals. Metal-allenylidene complexes can be easily obtained from terminal propargylic alcohols by dehydration of the initially formed metal-hydroxyvinylidenes, in which the reactivity of these metal complexes is based on the electrophilic nature of Ca and Cy, while Cp is nucleophilic. Catalytic processes based on nucleophilic additions and pericyclic reactions involving the it system of ruthenium allenylidenes afford interesting new structures with high selectivity and atom economy. 

Free vinylidene is a high-energy tautomer of an alkyne that can be effectively stabilized by coordination with transition metals [1-5]. Since the first formation and stabilization of vinylidenes at a transition metal center reported in 1966 [6, 7], a... 

Scheme 3.22. Synthesis of nitrogen-containing superben and its coordination with transition metal complexes.

Free hydrazine (N2H4), hydrazine hydrate, and monoprotonated hydrazine (N2H5" ) are all good ligands for coordination with transition metals. The monoprotonated hydrazine (N2H5+) has a lone pair of electrons and can coordinate to metal ions despite its low basicity. This is due to the presence of a positive charge adjacent to the donor atom that makes it a... 

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