Preparation of Pyrazole–Pyrazolate Half‐Sandwich Complexes of Ruthenium and Osmium

Abstract

AbstractPyrazole (HRpz) [MCl(η6‐p‐cymene)(HRpz)L]BPh4 (1–8) and imidazole (HIm) complexes [MCl(η6‐p‐cymene)(HIm)L]BPh4 (9–10) [M = Ru, Os; R = H, 3‐Me, 3,5‐Me2; L = P(OEt)3, PPh(OEt)2, PPh2OEt, CNtBu] were prepared by allowing the dichloro compounds MCl2(η6‐p‐cymene)L to react with the appropriate azole in the presence of NaBPh4. Treatment of the dichloro complexes with an excess of both pyrazole and NEt3 yielded the pyrazole–pyrazolate derivatives [M(Rpz)(η6‐p‐cymene)(HRpz)L]BPh4 (11–14). Conversely, the reaction of carbonyl compounds RuCl2(η6‐p‐cymene)(CO) with pyrazole or imidazole yielded the bisazole complexes [MCl(η6‐p‐cymene)(HRpz)2]BPh4 or [MCl(η6‐p‐cymene)(HIm)2]BPh4 (15–17). The complexes were characterised spectroscopically (IR and 1H, 13C, 31P NMR) and by X‐ray crystal structure analysis [RuCl(η6‐p‐cymene)(HRpz){PPh(OEt)2}]BPh4 (1b), [Ru(pz)(η6‐p‐cymene)(HRpz){P(OEt)3}]BPh4 (11a) and [RuCl(η6‐p‐cymene)(HRpz)2]BPh4 (15).