Abstract
The diacetate complexes trans-[Ru(κ(1)-OAc)(2)(PPh(3))(2)(NN)] (NN = ethylenediamine (en) (1), 2-(aminomethyl)pyridine (ampy) (2), 2-(aminomethyl)pyrimidine (ampyrim) (3)) have been isolated in 76-88% yield by reaction of [Ru(κ(2)-OAc)(2)(PPh(3))(2)] with the corresponding nitrogen ligands. The ampy-type derivatives 2 and 3 undergo isomerization to the thermodynamically most stable cationic complexes [Ru(κ(1)-OAc)(PPh(3))(2)(NN)]OAc (2a and 3a) and cis-[Ru(κ(1)-OAc)(2)(PPh(3))(2)(NN)] (2b and 3b) in methanol at RT. The trans-[Ru(κ(1)-OAc)(2)(P(2))(2)] (P(2) = dppm (4), dppe (5)) compounds have been synthesized from [Ru(κ(2)-OAc)(2)(PPh(3))(2)] by reaction with the suitable diphosphine in toluene at 95 °C. The complex cis-[Ru(κ(1)-OAc)(2)(dppm)(ampy)](6) has been obtained from [Ru(κ(2)-OAc)(2)(PPh(3))(2)] and dppm in toluene at reflux and reaction with ampy. The derivatives trans-[Ru(κ(1)-OAc)(2)P(2)(NN)] (7-16; NN = en, ampy, ampyrim, 8-aminoquinoline; P(2) = dppp, dppb, dppf, (R)-BINAP) can be easily synthesized from [Ru(κ(2)-OAc)(2)(PPh(3))(2)] with a diphosphine and treatment with the NN ligands at RT. Alternatively these compounds have been prepared from trans-[Ru(OAc)(2)(PPh(3))(2)(NN)] by reaction with the diphosphine in MEK at 50 °C. The use of (R)-BINAP affords trans-[Ru(κ(1)-OAc)(2)((R)-BINAP)(NN)] (NN = ampy (11), ampyrim (15)) isolated as single stereoisomers. Treatment of the ampy-type complexes 8-15 with methanol at RT leads to isomerization to the cationic derivatives [Ru(κ(2)-OAc)P(2)(NN)]OAc (8a-15a; NN = ampy, ampyrim; P(2) = dppp, dppb, dppf, (R)-BINAP). Similarly to 2, the dipivalate trans-[Ru(κ(1)-OPiv)(2)(PPh(3))(2)(ampy)] (18) is prepared from [Ru(κ(2)-OPiv)(2)(PPh(3))(2)] (17) and ampy in CHCl(3). The pincer acetate [Ru(κ(1)-OAc)(CNN(OMe))(PPh(3))(2)] (19) has been synthesized from [Ru(κ(2)-OAc)(2)(PPh(3))(2)] and HCNN(OMe) ligand in 2-propanol with NEt(3) at reflux. In addition, the dppb pincer complexes [Ru(κ(1)-OAc)(CNN)(dppb)] (CNN = AMTP (20), AMBQ(Ph) (21)) have been obtained from [Ru(κ(2)-OAc)(2)(PPh(3))(2)], dppb, and HAMTP or HAMBQ(Ph) with NEt(3), respectively. The acetate NN and pincer complexes are active in transfer hydrogenation with 2-propanol and hydrogenation with H(2) of carbonyl compounds at S/C values of up to 10000 and with TOF values of up to 160000 h(-1).