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

Abstract

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 tBuLi 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.