82807-97-4Relevant articles and documents
Reactions at the metal vertex of a monometal metallacarborane cluster. Chemistry of [closo-3,3-(PPh3)2-3-HSO4-3,1,2-RhC 2B9H11] and [coso-3-PPh3-3,3-NO3-3,1,2-RhC2B 9Hn]
Kalb, William C.,Demidowicz, Zenon,Speckman, Donna M.,Knobler, Carolyn,Teller, Raymond G.,Hawthorne, M. Frederick
, p. 4027 - 4036 (2008/10/08)
Reaction of [closo-3,3-(PPh3)2-3-H-3,1,2-RhC2B 9H11] (1) with sulfuric or nitric acid affords [closo-3,3-(PPh3)2-3-HSO4-3,1,2-RhC 2B9H11] (2) or [closo-3-PPh3-3,3-NO3-3,1,2-RhC 2B9H11] (3), respectively. Compound 3 can also be prepared from nitric acid and the dimeric metallacarborane [{closo-Rh(PPh3)(C2B9H11)} 2] or from NO2/N2O4 and 1. Complexes 2 and 3 have been used to prepare other new metallacarboranes, namely, [closo-3-PPh3-3,3-{C(Ph)-C(PPh 3)-C(H)-C-(Ph)}-3,1,2-RhC2B9H11] (5), [{closo-3-PPh3-3-(μ-CN)-3,1,2-RhC 2B9H11}4] (7), [closo-3-PPh3-3-L-3-NO3-3,NO3-3,1,2-RhC 2B9H11] (L = CO (8); L = PPh3 (9)), [closo-3,3-(PMe2Ph)2)2-3-NO 3-3,1,2-RhC2B9H11] (10), and [closo-3-PPh3-3-CO-3-Cl-3,1,2-RhC2B9H11] (11). Complexes 5 and 7 have been characterized by X-ray crystallography. The reactions of these new metallacarboranes described herein are representative of interconversions carried out at a discrete transition-metal vertex of a cluster species. Complex 5 crystallizes in space group P1 with 2 formula units in a cell of dimensions a = 12.763 (6) A?, b = 13.348 (5) A?, c = 14.561 (7) A?, α = 91.58 (3)°, β = 93.72 (3)°, and γ = 74.64 (3)°. Data were collected at -154 °C on a Picker FACS-1 diffractometer with the θ-20 scan method. Least-squares refinement, including anisotropic vibration parameters for Rh and P and isotropic vibration parameters for other non-hydrogen atoms, with each phenyl group described as a rigid group having a single isotropic vibration parameter, led to final conventional agreement indices (on F) of R = 0.048 and Rw = 0.051, based on 4493 unique reflections having I > 3σ(I). The molecule consists of a [C2B9H11]2- cage and a triphenylphosphine ligand bound to the metal atom of the trisubstituted metallapentacycle Rh-C(Ph)-C-(PPh3)-C(H)-C(Ph). Rh-C, Rh-B, B-B, B-C, and C-C distances are normal for a 3,1,2-RhC2B9 closo rhodacarborane fragment, and the pattern of short-long-short C-C bond lengths in the RhC4 ring is reminiscent of a pentasubstituted cis-butadiene. The complex 7-5C6H6 crystallizes in space group P2/a with 4 formula units in a cell of dimensions a = 26.046 (8) A?, b = 15.626 (3) A?, c = 30.355 (8) A?, and β = 106.71 (2)°. Data were collected at -154 °C on a Syntex P1 diffractometer with the θ-20 scan method. Least-squares refinement, including vibration parameters and rigid-group assignments as described above, led to final conventional agreement indices (on F) of R = 0.063 and Rw = 0.078, based on 9732 unique reflections having I > 3σ(I). The molecules consist of four discrete closo phosphinorhodacarborane moieties joined together through their respective metal vertices by cyano ligand bridges. Each tetramer possesses a crystallographic 2-fold axis; the two noncrystallographically equivalent tetramers are very similar. The Rh-Rh separation is approximately 5 A?. Bond distances within each icosahedral fragment are normal for such a closo Rh(III) metallacarborane.
