狩野 直和

The first aryl(arylthio)plumbylene, Tbt(TbtS)Pb: (2; Tbt=2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), teas obtained by the desulfurization of tetrathiaplumbolane, 1, with triphenylphosphine at 50 degrees C, and its structure was established by X-ray crystallographic analysis. The formation of 2 is most likely interpreted in terms of a 1,2-aryl migration in an initially formed plumbanethione, 8, followed by its dimerization and a subsequent metathesis reaction.

Reaction of a plumbylene Tbt(2)Pb: (1) with carbon tetrabromide in THF gave the first crystallographically characterized dibromoplumbane Tbt(2)PbBr(2) (2) bearing two 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) groups. The X-ray crystallographic analysis revealed that 2 has a monomeric structure with a distorted tetrahedral lead center.

Desulfurization of tetrathiaplumbolane 2 at 50 degrees C with three equivalent of triphenylphosphine afforded stable aryl(arylthio)plumbylene and dithiadiplumbetane. The formation of these products is most likely interpreted in terms of generation of a novel arylsulfido bridged cyclic organolead compounds.

Desulfurization of 1,2,3,4,5-tetrathiaplumbolanes 1 by a phosphine reagent gives the first lead-sulfur double-bond compounds, plumbanethiones 2. The cycloaddition reactions of plumbanethiones with MesCNO and PhNCS provide novel Pb-containing heterocycles.

The first examples of Pb-containing cyclic polysulfides, 1,2,3,4,5-tetrathiaplumbolanes (R(1)R(2)-PbS4: 2 (R(1) = Tbt, R(2) = Tip), 3 (R(1) = Tbt, R(2) = Ttm), and 4 (R(1) = R(2) = Tip); Tb t = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Tip = 2,4,6-triisopropylphenyl, and Ttm = 2,4,6-tris[(trimethylsilyl)methyl]phenyl), were synthesized and isolated as stable crystalline compounds by sulfurization of the corresponding kinetically stabilized diarylplumbylenes Tbt(Tip)Pb: (6), Tbt(Ttm)Pb: (7), and Tip(2)Pb: (10). The molecular structures of the novel lead-containing metallacycles 2 and 4 were determined by X-ray crystallographic analysis.

The first examples of Pb-containing cyclic tetrasulfides, R(Tip)PbS4 [4 (R=Tip) and 5 (R=Tbt); Tip=2,4,6-triisopropylphenyl, Tbt=2,4,6-tris[bis(trimethylsilyl)methyl]phenyl], were synthesized and isolated as stable crystalline compounds by the sulfurization of the corresponding overcrowded diarylplumbylenes, Tip(2)Pb: (6) and Tbt(Tip)Pb: (10). Molecular structures of 4 and 5 were determined by X-ray crystallographic analysis. Desulfurization reactions of the tetrathiaplumbolanes 4 and 5 leading to the formation of plumbanethiones R(Tip)Pb=S, novel lead-sulfur double bond compounds, are also described.