186510-97-4Relevant academic research and scientific papers
Half-sandwich rhenium(III) acyl complexes: Synthesis, structure and conversion to rhenium(I) and rhenium(III) isonitrile complexes 1
Filippou, Alexander C.,Lungwitz, Bernhard,Kociok-Koehn, Gabriele,Hinz, Isolde
, p. 133 - 146 (2007/10/03)
The synthesis, structure and reactions of rhenium(III) η1-acyl complexes bearing a cyclopentadienyl (Cp) or a pentamethylcyclopentadienyl (Cp *) ligand are described. Oxidation of the rhenium(I) acyl complex Li[CpRe(CO)2(η1-PhCO)] (1) with one equivalent of PhICl2 affords the rhenium(III) acyl complex trans-CpRe(CO)2(η1-PhCO)Cl (trans-2a). The diphenylcarbene complex Cp(CO)2Re=CPh2 (3) is also formed in this reaction. Similarly, oxidation of 1 with Br2 gives cis / trans-CpRe(CO)2(η1-PhCO)Br(cis / trans-2b), which can also be obtained from the alkoxycarbene complex Cp(CO)2Re=C(OEt)Ph (4) with one equivalent of Br2. Oxidation of Li[Cp*Re(CO)2(η1-PhCO)] (5) with one equivalent of PhICl2, Br2 or I2 affords selectively the rhenium(III) acyl complexes cis / trans-Cp*'e(CO)2(η1-PhCO)X (X = Cl-I) [cis / trans-(6a-6c)]. Cleavage of the Re-Cacyl bond of trans-2a with PhICl2 and of cis / trans-2b with Br2 offers a convenient way to the rhenium(III) dihalo complexes cis / trans-CpRe(CO)2Cl2 (cis / trans-7a) and cis / trans-CpRe(CO)2Br2 (cis / trans-7b) respectively. Reduction of cis / trans-7a with sodium/amalgam gives in the presence of RNC, the rhenium(I) isonitrile complexes CpRe(CO)2(CNR) (8: R = Et; 9: R = iPr; 10: R = tBu). Oxidation of 8-10 with one equivalent of bromine leads selectively to the rhenium(III) isonitrile complexes [trans-CpRe(CO)2(CNR)Br]Br (11: R = Et; 12: R = iPr; 13: R = tBu). The crystal structure of the acyl complex trans-2b and the carbonyl complex [Cp*2 Re2(CO)4(μ-Br)][Re2(μ-Br)3(CO)6] (14) are described, complex 14 being formed by the thermal decomposition of cis / trans-6b.
