3426-98-0Relevant academic research and scientific papers
Synthesis and characterization of anionic halogen-containing rhodacarboranes. Crystal and molecular structure of the hydrogen-bonded ion pair [HPPh3][closo-3-Ph3P-3,3-Br2-3,1,2-RhC 2B9H11]
Zheng, Limin,Baker, R. Thomas,Knobler, Carolyn B.,Walker, John A.,Hawthorne, M. Frederick
, p. 3350 - 3355 (2008/10/08)
The title compound was obtained in low yield from the reaction of closo-3,3-(Ph3P)2-3-H-3,1,2-RhC2B 9H11 (1) and BBr3 and was characterized by an X-ray diffraction study. Red crystals of [HPPh3][closo-3-Ph3P-3,3-Br2-3,1,2-RhC 2B9H11]·1.5C6H6, [HPPh3][3]·1.5C6H6, were triclinic, space group P1, with a = 12.591 (5) A?, b = 13.299 (4) A?, c = 17.568 (5) A?, α = 111.77 (2)°, β = 94.41 (3)°, γ = 61.24 (3)°, and Z = 2. The structure was solved by conventional heavy-atom techniques to a final discrepancy index of R = 0.046 for 6054 independent observed reflections. The rhodacarborane anion is pseudooctahedral about the rhodium atom, and the phosphonium cation is near the rhodium-bound bromine atoms with Br?H distances of 3.06 (6) and 2.70 (6) A?. It was suggested on the basis of NMR spectral data and solubility properties that ion pairing may also be significant for [HPPh3][3] in solution. It was found that K[18-crown-6][3] could be prepared in high yield from the anionic rhodacarborane K[18-crown-6] [closo-3,3-(Ph3P)2-3,1,2-RhC2B 9H11] and bromoform. The iodo analogue of 3- could be isolated as the (n-C4H9)4N+ salt, in high yield, from the reaction of closo-3-Ph3P-3,3-NO3-3,1,2-RhC2B 9H11, (n-C4H9)4NI, and NaI in dichloromethane/water. The chloro analogue of complex 3 could be prepared as the [Et4N]+ salt from the reaction of the 16-electron complex [Et4N][closo-3-Ph3P-3,1,2-RhC2B 9H11] (generated in situ) with CH2Cl2 in 60% yield.
