(FLUOROALKYL)PHOSPHINE COMPLEXES OF RHODIUM AND IRIDIUM - SYNTHESIS AND REACTIVITY PROPERTIES OF [(DFEPE)IR(MU-CL)]2

The synthesis, structure, and reactivity properties of iridium and rhodium (fluoroalkyl)phosphine dimeric complexes [(dfepe)M(mu-Cl)]2 (dfepe = (C2F5)2PCH2CH2P(C2F5)2; M = Rh (1); M = Ir (2)) are described. Complexes 1 and 2 are prepared in high yield from the displacement of cyclooctadiene from [(cod)M(mu-Cl)]2. X-ray diffraction studies reveal that 1 and 2 are isomorphous with identical M2(mu-Cl)2 dihedral hinge angles of 128-degrees. Complexes 1 and 2 exhibit high thermal stability and do not undergo oxidative addition reactions with H-2, O2, or alkyl halides. Although chloride abstraction or alkylation of 2 was unsuccessful, CpIr(dfepe) was prepared in good yield from the reaction of 2 with TlCp in refluxing THF. Addition of both donor and acceptor ligands to 2 produces monomeric products. Treatment of 2 with excess diethylamine affords (dfepe)Ir(NEt2H)C1(4), a surprisingly stable alkylamine complex which has been structurally characterized. Carbonylation reactions of both 1 and 2 are concentration- and solvent-dependent. In dilute acetone solutions, (dfepe)M(CO)Cl products are observed (M = Ir (5), nu(CO) = 2076 cm-1; M = Rh (6), nu(CO) = 2093 cm-1), which could not be isolated due to reversible CO loss in the absence of a CO atmosphere. At higher solution concentrations dfepe loss is observed concomitant with the formation of new solution species tentatively formulated as solvated oligomers, [(CO)2M(mu-Cl)(solv)]x. Crystal data for 1 (-100-degrees-C): trigonal, P3(2)21, with a = 14.215(2) angstrom, c = 34.545(8) angstrom, V = 6045(2) angstrom3, Z = 6, R = 6.32%, and R(w) = 6.64%. Crystal data for 2 (-100-degrees-C): trigonal, P3(2)21, with a = 14.159(2) angstrom, c = 34.649(7) angstrom, V = 6016(2) angstrom3, Z = 6, R = 6.28%, and R(w) = 6.49%. Crystal data for 4 (-100-degrees-C): orthorhombic, P2(1)2(1)2(1), with a = 11.262(2) angstrom, b 14.093(2) angstrom, c = 15.274(2) angstrom, V = 2424.2(6) angstrom3, Z = 4, R = 3.76%, and R(w) = 4.12%.