Chalcogen aryl complexes

Ge amidinate complexes are susceptible to oxidation of elemental chalcogens. Many of these complexes are excellent catalysts for the cycUzation of aryl isocyanates. ... 

Arylimido)vanadium(V) complexes have been prepared from the reaction of VOCl3 with various /wa-substituted aryl isocyanates. The reactivity and structure of some of these have been investigated (78).431 The reactivities of a series of vanadium(V) chalcogens have been reported. The structure of [(Me3Si)2N]2V(Se)[SeSi(SiMe3)3] 432 (79) shows that the V=Se double bond contracts by 8% compared to the single bond in a related dimeric vanadium(IV) structure (vide infra). The... 

The pattern of chemical reactions observed for these compounds clearly sets them apart from "Fischer-type" carbyne complexes of GroupVI e.g., W(hCR)X(CO)4. Whereas the "Fischer-type" complexes typically react with nucleophiles at the carbyne carbon all of the reactions observed for the five coordinate mthenium and osmium complexes, including the cationic examples, are electrophilic additions to the MsC bond. The following sections deal individually with, protonation, addition of halides of the coinage metals, addition of chlorine and chalcogens, and finally an attempted nucleophilic addition where the nucleophile is directed to a remote site on the aryl ring of the carbyne substituent. 

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