Group 13 metal carbochalcogenoato complexes: Synthesis, X-ray structure analysis, and reactions

A series of alkali metal tetrakis(carbochalcogenoato)-gallates and -indates M[M '(EOCR)(4)](solv.) (M = alkali metal; M ' = Ga, In; E = S, Se) and tris(carbodithioato)aluminum, -gallates and -indates M ' (SSCR)(3) (M ' = Al, Ga, In) were prepared by the reactions of alkali metal carbochalcogenate with metal trihalogenides (M ' X-3; M ' = Al, Ga, In; X = Cl, Br) and by those of piperidinium carbodithioates or carbodithioic and carboselenoic acids with M ' X-3, respectively. An X-ray molecular structure analysis revealed that they have an acetone molecule as a crystal solvent. The reactions of the potassium complexes K[M ' (EOCR)(4)](H2O) (E = S, Se) with methanol and primary and secondary amines gave the corresponding methyl ester and amides in good yields, while the reactions with iodomethane and iodine gave S- and Se-methyl chalcogenoesters RCOEMe (E = S, Se) in good yields. Similar reactions of the tris(carbodithioato)gallates and -indates led to the corresponding O-methyl thioesters, thioamides, and S-methyl dithioesters in moderate to good yields. Oxidation of the tetrakis- and tris-derivatives with iodine afforded the corresponding diacyl dichalcogenides (RCOE)(2) (E = S, Se) and di(carbothioyl) disulfides in quantitative yields. These reactions appeared to occur on the carbonyl or selenium atom of the tetrakis compounds and on the sulfide sulfur or thiocarbonyl carbon atom of the tris-compounds, respectively. A possible mechanism for these I-2-oxidation reactions is discussed.