Chalcogen alkyl complexes

Due to the reduced availability of the lone pair at the chalcogen atom, the sulfur or selenium atom in p -chalcogenoaldehyde or -ketone complexes cannot be alkylated by the usual alkylating agents. 

The ligands that have been used in the preparation of metal nitride complexes are quite varied. They include halides, carbogenic groups (alkyl moiety and Cp ), pnic-togens (amine, amide, imide, phosphine, and arsine), and chalcogens (ether, alkox-ide, oxo, thioalkoxide, and selenides). Chart 1 provides a listing of the various ligands and the associated nitrido metal complexes. 

The chemistry of l-phospha-4-boracyclohexa-2,5-dienes has been further developed to include preparations of the less substituted derivative (44) and its 1-arsa analogue (45) which is formed as a 2 1 mixture with its dihydro counterpart (46) (Scheme 6). The chemistry of (5) includes its methanolysis to (47), its oxidation with chalcogens to phosphorus(V) compounds (48), and its conversion to F-methyl and ethyl derivatives (49) with potassium in DME followed by alkylation with alkyl halides. The. B-r-butyl derivative (50) is also available from the addition of the alkylithium, but attempts to prepare the corresponding 5-Me derivative were thwarted by the failure of the intermediate ate complex (51) to undergo demethoxylation <83JOM(250)33>. 

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