97112-44-2Relevant articles and documents
Synthesis, structural characterization, and reactions of closo-rhodacarborane anions containing a formal d8 metal vertex
Walker, John A.,Knobler, Carolyn B.,Hawthorne, M. Frederick
, p. 2688 - 2697 (2008/10/08)
Deprotonation of three neutral closo hydrido complexes [(L)2-H-RhC2B9H11] under carefully controlled reaction conditions yields the corresponding isomeric [closo-L2RhC2B9H11]- species. Two of these have been structurally characterized. K[18-crown-6][closo-3,3-(PPh3)2-3,1,2-RhC 2B9H11]·C4H 8O·H2O (2a) crystallized in the monoclinic space group P21/c with a = 13.931 (4) A?, b = 19.954 (5) A?, c = 21.665 (7) A?, β = 100.97 (2)°, V = 5913 A?3, and Z = 4. Data were collected on a Syntex P1 diffractometer (Mo Ka radiation) to a maximum 2θ = 50°, giving 10521 unique reflections, and the structure was solved by conventional heavy-atom techniques. The final discrepancy index was R = 0.062, Rw = 0.072 for 6149 independent reflections. The d8-rhodacarborane anion adopts a closo structure similar to that found in the parent hydrido complex. The Rh-P2 plane lies almost perpendicular to the least-squares plane that passes through the bonding face of the carborane ligand and lies parallel to a line joining the two ortho carbon atoms of this ligand, in accord with theoretical studies. [Me4N][closo-2,2-(PPh3)2-2,1,7-RhC 2B9H11] (2b) crystallized in the triclinic space group P1 with a = 12.355 (13) A?, b = 14.896 (16) A?, c = 15.186 (22) A?, α = 68.00 (9)°, β = 102.86 (6)°, γ = 112.17(5)°, V = 2389 A?3, and Z = 2. Data were collected on a Picker FACS-1 diffractometer (Mo Ka radiation) to a maximum in 2θ of 45°, giving 6180 unique reflections, and the structure was solved by conventional heavy-atom techniques. The final discrepancy index was R = 0.063, Rw = 0.067 for 4761 independent reflections. Unlike 2a, this d8-rhodacarborane anion adopts a significantly distorted icosahedral structure. Carbon atoms of the significantly nonplanar C2B3 face are bent back into the cage and away from the metal. Rh-C bonds in 2b are 2.340 (9) and 2.442 (9) A?, while those in 2a are 2.314 (8) and 2.301 (7) A?. The plane containing RhP2 is nearly perpendicular to the C2B3 face and nearly parallel to the noncrystallographic mirror plane in the carborane ligand (the calculated preferred conformation). Salts of 2a-, 2b-, and [closo-2,2-(PPh3)2-2,1,12-RhC2B 9H11]- (2c) were treated with dilute mineral acids in ethanol to produce the neutral hydrido closo complexes and with π-acceptor ligands L = CO or C2H4 to produce the corresponding [closo-(PPh3)(L)-RhC2B9H11] salts. Anions [closo-3,3-(PPh3)2-3,1,2-IrC2B 9H11]-, [closo-3-(PPh3)-3,3-(H)2-3,1,2-IrC2B 9H11]-, and [closo-3-(PPh3)-3-(CO)-3,1,2-IrC2B9H 11]- have also been prepared.
