No abstract

The reaction of 1,1-dibutyl-1-stannacyclohexa-2,5-diene ( 8) with 1,2-bis(dichloroboryl)benzene 9 affords exchange product 10, which on deprotonation followed by reaction with ZrCl 4 gives the very labile o-phenylene-bridged bis(1-boratabenzene)zirconium dicholoride 6. A similar reaction sequence from 8 and 1,1-bis(dichloroboryl)-2-methyl-1-propene 11 affords the 1,1-isobutenyl-bridged bis(1-boratabenzene)zirconium dichloride 7. The X-ray structure of 7 is described.

The reaction of chloromethyl ethynyl sulfide with Bu 2 SnH 2 /LDA affords 2,3-dibutyl-2,3-dihydro-1,3-thiastannole which on reaction with AsBr 3 followed by DBU affords 1,3-thiaarsole in 22% yield. The reaction of allyl mercaptan with 2 equiv of BuLi followed by 1 equiv of Me 2 SnCl 2 affords an 80% yield of 2,3-dihydro-2,2-dimethyl-1,2-thiastannole which on reaction with AsBr 3 followed by DBU gives 1,2-thiaarsole in 56% yield. The NMR, UV and mass spectra are consistent with aromaticity of both thiaarsoles. The structure of 1,2-thiaarsole, measured by electron diffraction, suggests that it is an aromatic compound. The thermal average bond lengths (r g /Å) and bond angles (∠ R /deg) with estimated 2σ uncertainties are r(C-H) ) 1.078( 14), r(C 3 -C 4 ) ) 1.414(10), r(C 4 -C 5 ) ) 1.382(9), r(As-C) ) 1.829(4), r(S-C) ) 1.711(5), ∠(CCC) ) 118.0(12), ∠(AsCC) ) 117.7(10), ∠(SCC) ) 117.9(9), ∠(SAsC) ) 89.8(5), ∠(AsSC) ) 96.6(4). Ab initio molecular orbital calculations at the B3LYP/6-31G* level were performed for both thiaarsoles.

The reaction of 2-methylbenzenethiol with 2 equiv of BuLi followed by (i-Pr) 2 NBCl 2 affords 2,3dihydro-2-(diisopropylamino)-1,2-benzothiaborole ( 10), which can be deprotonated by t-BuLi to form lithium 2-(diisopropylamino)-1,2-benzothiaborolide ( 3). The benzothiaborolide was converted to the Cp*ZrCl 2 complex 11 and the Cp*Ru complex 12, in which the thiaborolide ring is η 5 -coordinated to Ru.