REACTIVITY AND CHEMICAL-EXCHANGE PROCESSES OF BIS(ETHER-PHOSPHINE) IRIDIUM(III) COMPLEXES

The orthometalated indium(III) complex CIIrH(POCH2)(PO) (POCH2 = eta(2 )(P, OCH2) coordination of Cy2PCH2CH2OCH2, PO = eta(2)(P, O) coordinat ion of Cy2PCH2CH2OCH3) (1) reacts with CS2, HCl, and H-2 under re-form ation of the methoxy group to give CIIr(eta(2)-CS2)(P similar to O)(2) (3) (P similar to O =eta 1(P) coordination of Cy2PCH2CH2OCH3), trans- (PO)(P similar to O)Ir(H)Cl-2 (4a) and CIIrH2(PO)(P similar to O) (5), respectively. Upon the reaction of 1 with CO the orthometalation is m aintained to yield the carbonyl adduct CIIrH(CO)(POCH2)(P similar to O ) (2). Compounds 4a and 5 represent potentially unsaturated speices we akly protected by the ether moiety which acts as an intramolecular sol vent. The chelated five-membered ring in 4a, cis-(PO)(P similar to O)I r(H)Cl-2 (4b) and 5 can easily be cleaved by carbon monoxide, pyridine and CS2 whereby the complexes Cl2IrH(CO)(P similar to O)(2) (7), CIIr H2(C5H5N)(P similar to O)(2) (10), CIIrH2(CO)(P similar to O)(2) (11) and the dithioformato complex cis-(P similar to O)(2)Ir(H)Cl(S2CH) (13 a) are formed. In toluene 13a isomerizes to give the trans-product 13b . Comparative NMR studies on the fluxional behavior of the ether phosp hine ligands of the five monochelated complexes 4a, b, 5, IrH3(P simil ar to O)(2) (6) and Cl3Ir(PO)(P similar to O) (9a) were performed to d etermine the dependence of the exchange rates on the strength of the i ndium-(ether) oxygen bond. Complex 9b, the phenyl congener of 9a, crys tallizes in the orthorhombic space group Pna2(1) with Z = 4. The cell dimension are a = 1695.2(3), b = 1093.4(2), c = 1621.5(9) pm, R-1 = 0. 018 and wR(2) = 0.042. (C) 1998 Elsevier Science S. A.