Oxidative addition of different electrophiles with rhodium(I) carbonyl complexes of unsymmetrical phosphine-phosphine monoselenide ligands

Dimeric chlorobridge complex [Rh(CO)2Cl]2 reacts with two equivalents of a series of unsymmetrical phosphine–phosphine monoselenide ligands, Ph2P(CH2)nP(Se)Ph2 {n = 1(a), 2(b), 3(c), 4(d)}to form chelate complex [Rh(CO)Cl(P∩Se)] (1a) {P∩Se = η2‐(P,Se) coordinated} and non‐chelate complexes [Rh(CO)2Cl(P∼Se)] (1b–d) {P∼Se = η1‐(P) coordinated}. The complexes 1 undergo oxidative addition reactions with different electrophiles such as CH3I, C2H5I, C6H5CH2Cl and I2 to produce Rh(III) complexes of the type [Rh(COR)ClX(P∩Se)] {where R = C2H5 (2a), X = I; R = CH2C6H5 (3a), X = Cl}, [Rh(CO)ClI2(P∩Se)] (4a), [Rh(CO)(COCH3)ClI(P∼Se)] (5b–d), [Rh(CO)(COH5)ClI‐(P∼Se)] (6b–d), [Rh(CO)(COCH2C6H5)Cl2(P∼Se)] (7b–d) and [Rh(CO)ClI2(P∼Se)] (8b–d). The kinetic study of the oxidative addition (OA) reactions of the complexes 1 with CH3I and C2H5I reveals a single stage kinetics. The rate of OA of the complexes varies with the length of the ligand backbone and follows the order 1a > 1b > 1c > 1d. The CH3I reacts with the different complexes at a rate 10–100 times faster than the C2H5I. The catalytic activity of complexes 1b–d for carbonylation of methanol is evaluated and a higher turnover number (TON) is obtained compared with that of the well‐known commercial species [Rh(CO)2I2]−. Copyright © 2006 John Wiley & Sons, Ltd. Four new curcuminoid analogues (HL) and their copper complexes [CuL2] were synthesized and characterized by UV, IR, 1H NMR, ESR and mass spectral data. The compounds were investigated for their possible cytotoxic and antitumour activities. The copper complex of 1a with hydroxyl group in the phenyl ring was found to be most active towards L929cells (1 mg/ml produced 43.3 ± 1.3% cell death).