Preparation of Half-Sandwich Azine Complexes of Osmium

Half-sandwich azine complexes [OsCl(g6-p-cymene){j1-[N@C(H)C6H4R1]–N@C(H)C6H4R1}{P(OR)3}] BPh4 (1, 2) and [OsCl(g6-p-cymene){j1-[N@C(CH3)2]N@C(CH3)2}{P(OR)3}]BPh4 (3, 4) [R = Me (1, 3), Et (2, 4); R1 = H (a), 4-CH3 (b), 2,6-(CH3)2 (c)] were prepared by allowing chloro compounds [OsCl2(g6-pcymene){P(OR)3}] to react first with one equivalent of AgOTf and then with azine. Instead, treatment of chloro compounds with acetone azine afforded hydrazone derivatives [OsCl(g6-p-cymene){NH2N@ C(CH3)2}{P(OR)3}]BPh4 (5, 6) [R = Me (5), Et (6)]. In solution, j1-azine complexes undergo metalation reaction, giving chelate derivatives (g6-p-cymene){P(OR)3}] BPh4 (7, 8) [R = Me (7), Et (8); R1 = H (a), 4-CH3 (b)]. The complexes were characterised by spectroscopy (IR, NMR) and X-ray crystal structure determination of [OsCl(g6-p-cymene){j1-[N@C(H)Ph]–N@C(H)Ph} {P(OEt)3}]BPh4 (2a)