53687-46-0Relevant articles and documents
Paxson, T. E.,Hawthorne, M. F.
, p. 4674 - 4676 (1974)
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.
Metallacarboranes in Catalysis. 2. Synthesis and Reactivity of Closo Icosahedral Bis(phosphine)hydridorhodacarboranes and the Crystal and Molecular Structures of Two Unusual closo-Phosphinerhodacarborane Complexes
Baker, R. Thomas,Delaney, Mark S.,King, Roswell E.,Knobler, Carolyn B.,Long, Judith A.,et al.
, p. 2965 - 2978 (2007/10/02)
A series of closo icosahedral rhodacarboranes bearing substituents at carbon has been synthesized by the reaction of with the correspondingly C-substituted nido-carborane anions: from (1-) where R = R' = H; R = R' = D; R = H and R' = Ph, Me, and n-Bu; from (1-) where R = H, Ph, and Me; and from (1-).These closo icosahedral rhodacarboranes are catalytically active in alkene isomerization and hydrogenation reactions, among others.The B-D-B-bridge deuterated (1-) gave when reacted with , establishing the regiospecific transfer of BHB hydrogen to Rh-H in the synthesis reaction.The complex is apparently transformed to by a polytopal rearrangement under mild conditions.The optically active catalyst was employed to hydrogenate ethyl α-phenylacrylate to give ethyl α-phenylpropionate in 3percent enantiomeric excess.In the absence of hydrogen this chiral catalyst reacted with certain esters of the acrylic type to yield alkyl chelates in which the alkene function of the ester had undergone migratory insertion into the Rh-H and the ester carbonyl oxygen became bound to Rh.One of these chelates, derived from the d-catalyst and n-butyl acrylate, was characterized crystallographically.The compound crystallizes in the space group P212121 with unit cell parameters a = 24.578 (5) Angstroem, b = 12.543 (2) Angstroem, and c = 10.377 (2) Angstroem, four molecules per unit cell.The structure was solved by conventional heavy-atom methods and refined to a final value of R = 0.069, Rw = 0.080 (3159 reflections).The absolute configuration of the d-catalyst and the (1-), from which it was derived, was thus established.Reaction of the unsubstituted compounds and (L = PPh3) with more basic phosphines gave the corresponding L2 compounds with L = PEt3, PMe2Ph, and for the 3,1,2-isomer, L2 = Ph2PCH2CH2PPh2.Reaction of the unsubstituted 3,1,2-isomer (L = PPh3) with HCl in CHCl3 gave .The analogous chloro compound in which L = PMe2Ph was prepared by the reaction of the Rh-H species with CH2Cl2.Reaction of with HCl/CHCl3 produced the coordinatively unsaturated 16-electron species .This complex reacted with CO and ligands to produce coordinatively saturated adducts.A crystallographic study of the 16-electron 2,1,7-chloride was carried out.This compound crystallizes in the monoclinic system P21/n, a = 13.840 (5) Angstroem, b = 17.000 (7) Angstroem, c = 13.771 (6) Angstoem, and β = 118.98 (2) deg, four molecules of complex and...
