119326-28-2Relevant academic research and scientific papers
Synthesis, oxidative addition, and structural studies of the metal-metal bonded bimetallic complexes [(η-C5H5)Rh(μ-CO)(μ-Ph2PC 5H4N)M(CO)Cl] (M = Rh, Ir)
Bruno, Giuseppe,Schiavo, Sandra Lo,Rotondo, Enrico,Arena, Carmela Grazia,Faraone, Felice
, p. 886 - 892 (2008/10/08)
Reaction of [Rh(η5-C5H5)(CO)2] or [Rh2(η5-C5H5) 2(CO)3] with 2-(diphenylphosphino)pyridine (Ph2PPy) gave [Rh(η5-C5H5)(CO)(Ph2PPy)] (1) in which Ph2PPy acts as monodentate P-bonded ligand. Compound 1 reacted with [Rh(CO)2Cl]2 and [Ir(CO)2(p-toluidine)Cl] to give the Ph2PPy-bridged complexes [(η5-C5H5)Rh(μ-CO)(μ-Ph 2PPy)Rh(CO)Cl] (2) and [(η5-C5H5)Rh(μ-CO)(μ-Ph 2PPy)Ir(CO)Cl] (3), respectively, in which a metal-metal bond is present. The structure of the unsymmetrical bimetallic compound 2 has been determined by X-ray crystallography. The crystal is monoclinic with space group P21/c, and the cell constants are a = 15.928 (2) A?, b = 11.322 (2) A?, c = 26.646 (4) A?, β = 104.2 (2)°, and Z = 8. The structure has been refined to a final R value of 0.042. The unit cell contains two crystallographically independent molecules that have very similar structures. The structure is characterized by the short Rh(1)-Rh(2) bond distance of 2.648 (1) A?, by the different coordination geometry of the two rhodium atoms, and by the presence of an asymmetric CO bridging ligand. The ligands about Rh(1) are disposed in an approximately tetrahedral environment, and the Rh(2) coordination geometry is that of a distorted square pyramid with the vertex shifted toward the Rh(1)-Rh(2) vector. The Ph2PPy is twisted about the Rh(1)-Rh(2) bond to avoid unfavorable contacts. 2 reacts with SO2 to produce [(η5-C5H5)Rh(μ-Ph 2PPy)(μ-SO2)Rh(CO)Cl] (4). The addition of Cl2 or Br2 to 2 gave the rhodium(III) complexes [(η5-C5H5)X2Rh(μ-Ph 2PPy)Rh(CO)X3] (5, X = Cl; 6, X = Br); the same reaction with I2 occurred with formation of [(η5-C5H5)Rh(μ-I)(μ-Ph 2PPy)Rh(CO)I2] (7) and [(η5-C5H5)I2Rh(μ-Ph 2PPy)Rh(CO)I3] (8). Spectroscopic data indicated that 7 is a RhII-RhII species. It crystallizes in the monoclinic system, space group P21/c, with a = 7.847 (1) A?, b = 16.995 (2) A?, c = 19.446 (3) A?, β = 96.4 (1)° and Z = 4. The structure has been refined to a final R value ot 0.026. The rhodium atoms are bridged by the Ph2PPy and I(1) ligands. The Rh(1)-Rh(2) bond distance of 2.686 (1) A? is very close to that of the precursor 2. The bond angles at Rh(1) atom reflect a large deviation from the tetrahedral coordination geometry. The Rh(2) atom displays a distorted octahedral geometry; significant deviations are with the terminal I(3) and bridging I(1) atoms. The geometry of the bridging iodo ligand appears normal. The structural features of the bridging Ph2PPy and of the cyclopentadienyl ring are essentially the same as in the precursor 2. Compounds 7 and 8 have been the only products obtained from the reaction of 2 with CH2I2.
