Tetrakis dibismuthines

Tetrakis(trimethylsilyl)dibismuthine has a tram-staggered conformation, shown to good effect in the stereoview (72).203 The intramolecular d Bi—Bi) is 3.035 A and the intramolecular d(Bi- -Bi) is 3.804 A. The Bi—Bi distance averages 2.68 A. The molecules are linked into chains in the crystal, allowing electronic excitations along the chain, accounting for the green metallic lustrous appearance of these crystals. The compound is red in the liquid state. 

Fewer structural data are available for dibismuthines. Published structures include only the thermochromic tetrakis(trimethylsilyl)dibismu-thine (37) (57) and the nonthermochromic tetraphenyldibismuthine (46) (42) although some data from an unpublished structure of tetramethyl-... 

Diphenyl disulfide (0.14 g, 0.64 mmol) was added with vigorous stirring to a solution of tetrakis(4-methylphenyl)dibismuthine (0.50 g, 0.64 mmol) in dichloromethane (15 ml) at 0°C under an argon atmosphere. The reaction mixture turned pale yellow within several minutes. After 15 min the reaction mixture was concentrated to a half volume in vacuo, diluted with pentane (3 ml), and poured onto crushed dry ice. After decantation, the yellow residue was washed with pentane and dried in vacuo to obtain the product (0.57 g, 89%) [87ZN(B)695]. 

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