Two Isomeric Phosphacarboranes 2,1- and 6,1-PCB8H9, the First Representatives of the 10-Vertex closo Phosphacarborane Series
journal contributionposted on 07.05.2002, 00:00 by Josef Holub, Mario Bakardjiev, Bohumil Štíbr, Drahomír Hnyk, Oleg L. Tok, Bernd Wrackmeyer
The reaction between arachno-4-CB8H14 and PCl3 in the presence of PS (PS = proton sponge = 1,8-dimethylamino naphthalene) (dichloromethane, rt, 24 h) produced the neutral phosphacarborane closo-2,1-PCB8H9 (35% yield), while a similar reaction of nido-1-CB8H12 gave the isomeric compound closo-6,1-PCB8H9 (27% yield). The structures of both compounds were derived on the basis of the combined ab initio/GIAO/NMR (1H, 11B, 13C) approach. The optimized structures at a correlated level of theory (MP2) with 6-31G* basis set were used as a basis for calculations of the 11B and 13C chemical shifts at GIAO-SCF/II and GIAO-MP2/II, the latter showing excellent agreement with experimental data.