New Rhodium(I) Complexes with Hemilabile Amphiphilic Phosphanes

Abstract

AbstractA series of RhI complexes was prepared and characterised with the following hemilabile amphiphilic phosphanes: R−(C6H4)−(OCH2CH2)n−PPh2 [1 (R = tert‐octyl, n = 1), 2 (R = tert‐octyl, $\bar n$ = 5), 3 (R = tert‐octyl, $\bar n$ = 13), 4 (R = n‐nonyl, $\bar n$ = 1.4), 5 (R = n‐nonyl, $\bar n$ = 5), 6 (R = n‐nonyl, $\bar n$ = 11)]. The reactions between 1−6 and [Rh(COD)(THF)2]+, and the subsequent reaction with CO were studied by 31P NMR and IR spectroscopy. The data are consistent with the formation of P‐coordinated and chelated (P,O) species for ligands 2−6, in agreement with the hemilabile character of these ligands. In the case of ligand 1, the complex trans‐[Rh(1)2(CO)2]+ has been isolated and the cis‐[Rh(1)2(CO)2]+ compound has been detected. [Rh(1)2(CO)]+ was prepared by decarbonylation of trans‐[Rh(1)2(CO)2]+, and low‐temperature NMR spectroscopic studies have shown the hemilabile character of 1 with a very weak P−O interaction. The molecular structure of trans‐Rh(CO)(1)2Cl was determined by X‐ray crystallography and shows that the conformation of the tert‐octylphenoxyethyl chains is nearly identical to that previously reported in the complex trans‐PdCl2(1)2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)