Preparation of Azine Complexes of Ruthenium(II)

Aldazine complexes [RuCl(η6-p-cymene){κ1-[N=C(H)R1]-N=C(H)R1}L]BPh4 (1-4) [L=P(OMe)3, P(OEt)3, PPh(OEt)2, PiPr3; R1=Ph, 4-CH3C6H4, 4-CH3OC6H4, Et] were prepared by allowing chloro compounds RuCl2(η6-p-cymene)L to react with the azine R1(H)C=N-N=C(H)R1 in ethanol. Depending on the nature of the phosphine ligand, the reaction of ketazine (CH3)2C=N-N=C(CH3)2 with chloro compounds RuCl2(η6-p-cymene)L yielded either hydrazone derivatives [RuCl(η6-p-cymene){NH2N=C(CH3)2}L]BPh4 (5,6) [L=P(OMe)3, P(OEt)3] or κ1-azine complex [RuCl(η6-p-cymene){κ1-[N=C(CH3)2]N=C(CH3)2}(PiPr3)]BPh4 (7). Cyclopentadienyl derivatives [Ru(η5-C5H5){κ1-[N=C(H)R1]-N=C(H)R1}(PPh3){P(OMe)3}]+ (10) [R1=Ph, 4-CH3C6H4, C2H5] were prepared by reacting the chloro compound RuCl(η5-C5H5)(PPh3)[P(OMe)3] first with AgOTf and then with an excess of azine. Instead, treatment of RuCl(η5-C5H5)(PPh3)[P(OMe)3] first with AgOTf and then with ketazine (CH3)2C=N-N=C(CH3)2 in ethanol, yielded hydrazone derivative [Ru(η5-C5H5){NH2N=C(CH3)2}(PPh3){P(OMe)3}]BPh4 (11). Oxidation of hydrazone derivative 11 with HgO gave dimethyldiazoalkane complex [Ru(η5-C5H5){N2C(CH3)2}(PPh3){P(OMe)3}]BPh4 (13). The complexes were characterised by spectroscopy and X-ray crystal structure determination of [RuCl(η6-p-cymene){κ1-[N=C(H)Ph]-N=C(H)Ph}{P(OMe)3}]BPh4 (1 a), [RuCl(η6-p-cymene){κ1-[N=C(H)Ph]-N=C(H)Ph}{P(OEt)3}]BPh4 (2 a) and [Ru(η5-C5H5){NH2N=C(CH3)2}(PPh3){P(OMe)3}]BPh4 (11).