The Chemistry of Various Tetraorganodistibines and Tetraorganodibismuthines.

Recent X-ray crystallographic analyses of thermochromic distibines show that the metal atoms form a nearly linear chain with unusually close intermolecular contacts. Presumably there is an extended bonding along this Sb-Sb(.)(.)(.)Sb-Sb chain and the color is probably due to electronic excitation along the chain. These distibines and dibismuthines, a new class of one-dimensional materials, have not been well explored. We have undertaken the synthesis and study of new distibines and dibismuthines in an attempt to define the requirements for thermochromism, study the properties of these compounds and attempt to "fine-tune" the intermolecular metal-metal distances by adjusting the steric bulk of the organic substituents. New tetravinyldistibines R(,4)Sb(,2) (where R = vinyl, 1; isopropenyl, 2; (E)- and (Z)-propenyl, 3 and 4; (E)-1-methyl-1-propenyl, 5, and 2-methyl-1-propenyl, 6, have been prepared from the reaction of the corresponding tertiary stibines with active metals in liquid ammonia followed by treatment with 1,2-dichloroethane. While all the distibines show yellow liquid phases, 1 and 2 freeze to violet and orange solids. Compounds 3-6 freeze to yellow solids. In an analogous manner, tetramethyldibismuthine, 7, tetraisopropenyldibismuthine, 8, and tetrakis(2-methyl-1-propenyl)dibismuthine, 9, have been prepared from the tertiary bismuthines. While all of the dibismuthines are red liquids, 7 and 8 freeze reversibly to blue and purple solids and 9 freezes to a red solid. The dibismuthines decompose thermally to give the tertiary bismuthines and bismuth metal. The ('1)H NMR, Raman, IR, UV, solid reflectance and mass spectra of compounds 1-9 have been studied. The reactions of tetramethyldibismuthine, -distibine and -diarsine with a variety of free radical, electrophilic and nucleophilic reagents have been studied. The reactions afforded products in which the metal-metal bonds had been cleaved. The exchange reactions of the tetramethyldipnicogens, forming the interpnicogen compounds, were explored. In addition, the exchange reactions of the tetramethyldipnicogens with the dimethyldichalcogens, forming compounds containing pnicogen-chalcogen bonds, were studied.PhDOrganic chemistryUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159988/1/8412199.pd