Developments in Chalcogen-Halide Chemistry

The fundamental chemistry and compounds reported prior to 1984 are summarized in CCC (1987). The development and expansion of coordination chemistry provided many possibilities and opportunities for the selection of ligands. Many combinations of coordinated atoms have been reported including halogen, chalcogen, nitrogen, phosphorus, carbon, and hydrogen. Initially, classical halides and their derivatives are described, followed successively by less electronegative atoms. 

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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