Rhenium complexes alkyl derivatives

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

Apart from the platinum and nickel compounds with cr-bonded alkyl or aryl ligands, Chatt s group reported between 1961 and 1966 the synthesis of an impressive series of related cobalt(II), iron(II), rhodium(III), iridium(III), rhe-nium(III) and rhenium(V) complexes [39-42]. The paramagnetic cobalt(II) and iron(II) derivatives MR2(PR 3)2 were stable when R was an aryl group with... 

The lability of the N2 ligand towards alkyl and aryl isocyanides has been demonstrated by equation (2) which occurs readily with both alkyl and aryl isocyanides.40 The resulting complexes are electron rich , the alkyl isocyanide derivatives ReCl(CNR)(dppe) (R = Me or Bul) undergoing electrophilic attack upon treatment with HBF4 to form the carbyne complexes trcms-[ReCl(CNHR)(dppe)2]BF4.41 Other noteworthy features of the series of complexes ReCl(CNR)(dppe)2 and ReCl(CNAr)(dppe)2, are the low value of v(CN), the presence of a bent M—CNR coordination mode, and their ease of oxidation (as measured by cyclic voltammetry) to the corresponding rhenium(II) monocations.40... 

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