Synthesis of Cage Compounds Containing Boron, Germanium, and Phosphorus Atoms

Article abstract of DOI:10.1021/ic961026n

The 1:1 reactions of [(ⁱPr₂N)BP(H)B(NⁱPr₂)PLi·DME] and [(tmp)BP(H)B(tmp)PLi·DME] (tmp = 2,2,6,6-tetramethylpiperidino) with organylhalogermanes have been surveyed, and germyl-substituted diphosphadiboretanes of the type R₂NBP(H)B(NR₂)PGe(Cl)R'₂ (R₂N = ⁱPr₂N, tmp; Ge(Cl)R'₂ = Ge(Cl)Me₂ and Ge(Cl)Ph₂) have been isolated and characterized. Subsequent dehydrohalogenation of these compounds with BuLi gave the new bicyclic cage compounds P₂(BNR₂)₂(GeR'₂) (R₂N = tmp, R'=Ph; R₂N = tmp, R' = Me) and/or oligomers [-(R₂N)BP(H)B(NR₂)PGeR'₂-]_n (R₂N = ⁱPr₂N, R' = Me; R₂N = tmp, R' = Me). In addition, the 2:1 reactions of [(R₂N)BP(H)B(NR₂)PLi·DME] with R'₂GeCl₂ have been examined. In one case, the cage compound P₂(BNR₂)₂GeR'₂ (R₂N = tmp, R' = Ph) was obtained while a smaller alkyl group on Ge allowed formation of the bis(diphosphadiboretanyl)germanes [R₂NBP(H)B(NR₂)P]₂GeR'₂ (R₂N = ⁱPr₂N, tmp; R' = Me). Two P₂(BNR₂)₂(GeR'₂)·Cr(CO) ₅ (complexes R₂N = tmp, R' = Ph, Me) were isolated and characterized. The molecular structures of the cage compound P₂(Btmp)₂GePh₂ and the complexes P₂(Btmp)₂GeR'₂·Cr(CO)₅ (R' = Ph, Me) were determined with single-crystal X-ray diffraction techniques. The structural and spectroscopic features are discussed in relation to those of other P₂(BNR₂)₂(ER₂) species.