Low oxidation state ruthenium chemistry

Arylazo derivatives of ruthenium (A), [Ru(N2C6H4R-p)(CO)2L2]+(X−) (L = PPh3, R = NO2, F, H, OMe, X = BF4; L = PPh3 R = F, NMe2, X = BPh4; L = PPh2(C6H4Me-p), R = OMe, X = BF4) and Ru(N2C6H3R2-2,6)(CO)2(PPh3)2]+(BF−4) (R = Me, Cl), have been prepared by reacting diazonium salts with the complexes Ru(CO)3L2. Their reactions with HX (H = BF4, Cl, I) or LiCl gave the aryldi-imine derivatives (B), [Ru(N2HC6H4R-p)(CO)2l2]++(BF−4)2, [RuI(N2HC6H4F-p)(CO)2(PPh3)2]+(I−3) and RuCl2(N2HC6H4R-p)(CO)(PPh3)2 (R = F, OMe). Deprotonation reactions with organic or inorganic bases of some of compounds (B) regenerated the starting arylazo complexes (A). The unusual spectroscopic properties of the new compounds are reported and discussed, and it has been shown that the interaction with carbon dioxide of the arylazo complexes (A) when in solution is in part responsible for the anomalous i.r. absorptions observed in the carbonyl stretching frequencies region. A comparison with the properties of the homologous, already known iron arylazo complexes has shown that the only reactions in which they behave analogously are the reactions with NaBH4, which gave the hydrides cis-MH2(CO)2(PPh3)2 and with LiOEt, which gave the very reactive zerovalent complexes, M(CO)2(PPh3)3(M = Fe, Ru).