title: Synthesis and structure of dirhodium analogue of octaborane-12 and decaborane-14.
abstract: We present the results of our investigation of a thermally driven cluster expansion of rhodaborane systems with BH(3)·THF. Four novel rhodaborane clusters, for example, nido-[(Cp*Rh)(2)B(6)H(10)], 1; nido-[(Cp*Rh)B(9)H(13)], 2; nido-[(Cp*Rh)(2)B(8)H(12)], 3; and nido-[(Cp*Rh)(3)B(8)H(9)(OH)(3)], 4 (Cp* = η(5)-C(5)Me(5)), have been isolated from the thermolysis of [Cp*RhCl(2)](2) and borane reagents in modest yields. Rhodaborane 1 has a nido geometry and is isostructural with [B(8)H(12)]. The low temperature (11)B and (1)H NMR data demonstrate that compound 1 exists in two isomeric forms. The framework geometry of 2 and 3 is similar to that of [B(10)H(14)] with one BH group in 2 (3-position), and two BH groups in 3 (3, 4-positions) are replaced by an isolobal {Cp*Rh} fragment. The 11 vertex cluster 4 has a nido structure based on the 12 vertex icosahedron, having three rhodium and eight boron atoms. In addition, the reaction of rhodaborane 1 with [Fe(2)(CO)(9)] yielded a condensed cluster [(Cp*Rh)(2){Fe(CO)(3)}(2)B(6)H(10)], 5. The geometry of 5 consists of [Fe(2)B(2)] tetrahedron and an open structure of [(Cp*Rh)(2)B(6)], fused through two boron atoms. The accuracy of these results in each case is established experimentally by spectroscopic characterization in solution and structure determinations in the solid state.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India.
authors.forename: Dipak Kumar
authors.initials: DK
authors.lastname: Roy
authors.forename: Shubhankar Kumar
authors.initials: SK
authors.lastname: Bose
authors.forename: R S
authors.initials: RS
authors.lastname: Anju
authors.forename: V
authors.initials: V
authors.lastname: Ramkumar
authors.forename: Sundargopal
authors.initials: S
authors.lastname: Ghosh