Reactions of POP-pincer rhodium(I)-aryl complexes with small molecules: coordination flexibility of the ether diphosphine

Reactions of the aryl complexes Rh(aryl){? 3 -P,O,P-[xant(P i Pr 2 ) ]} (1; = 3,5-Me C 6 H (a), 5 (b), 3,5-Cl (c), 3-FC 4 (d); xant(P 9,9-dimethyl-4,5-bis-(diisopropylphosphino)xanthene) with O , CO, and MeO CC?CCO Me have been performed. Under 1 atm pentane solutions afford dinuclear peroxide derivatives [Rh(aryl){? -P,P-xant(P }] (?-O (2a–2d) as yellow solids. In solution, these species are unstable. dichloromethane, at room temperature, they transformed into dioxygen adducts Rh(aryl)(? -O ){? (3a–3d), a result rupture double bridge reduction metal center. Complex 3b decomposes in benzene, 50 °C, to give diphosphine oxide, phenol, biphenyl. Complexes react CO square-planar mono carbonyl Rh(aryl)(CO){? -P,P-[xant(P (4a–4d), which under carbon monoxide atmosphere evolve benzoyl Rh{C(O)aryl}(CO){? (5a–5d), resulting from migratory insertion Rh-aryl bond coordination second molecule. The transformation is reversible; vacuum, regenerate precursors 4. addition activated alkyne 1b 1d initially leads ?-alkyne intermediates Rh(aryl){? -C(CO Me)?C(CO Me)}{? (6b, 6d), alkenyl Rh{(E)-C(CO Me)=C(CO Me)aryl}{? (7b, 7d). adapts its mode stability requirements different complexes, coordinating cis-? -P,P 2, fac-? -P,O,P compounds 3, trans-? 5, mer-? products 7.