Reactivity and chemical exchange processes of bis(ether-phosphine) iridium(III) complexes

Abstract

The orthometalated iridium(III) complex ▪ ▪ coordination of Cy 2PCH 2CH 2OCH 2, ▪coordination of Cy 2PCH 2CH 2OCH 3) (1) reacts with CS 2, HCl and H 2 under re-formation of the methoxy group to give Cllr( ν 2-CS 2) (P∼O) 2 ( 3) (P ∼ O = ν 1( P) coordination of Cy 2PCH 2CH 2OCH 3, ▪ ( 4a) and ▪ respectively. Upon the reaction of 1 with CO the orthometalation is maintained to yield the carbonyl adduct ▪ Compounds 4a and 5 represent potentially unsaturated species weakly protected by the ether moiety which acts as an intramolecular solvent. The chelated five-membered ring in 4a, ▪ ( 4b) and 5 can easily be cleaved by carbon monoxide, pyridine and CS 2 whereby the complexes Cl 2IrH(CO)(P∼O) 2 ( 7), CllrH 2(C 5H 5N)(P∼O) 2 ( 10), CllrH 2(CO)(P∼O) 2 ( 11) and the dithioformato complex cis-(P∼O) 2Ir(H)S 2CH) ( 13a) are formed. In toluence 13a isomerizes to give the trans-product 13b. Comparative NMR studies on the fluxional behavior of the ether phosphine ligands of the five monochelated complexes 4a,b,5, IrH 3( P∼ O) 2( 6) and ▪ were performed to determine the dependence of the exchange rates on the strength of the iridium-(ether)oxygen bond. Complex 9b, the phenyl congener of 9a, crystallizes in the orthorhombic space group Pna2 1 with Z = 4. The cell dimensions are a = 1695.2(3), b = 1093.4(2), c = 1621.5(9) pm, R 1 = 0.018 and wR 2 = 0.042.