Dihydrobis(methimazolyl)borato complexes of ruthenium and osmium

Abstract

The reaction of Na[H₂B(mt)₂] (mt = 2-mercapto, 3-methylimidazol-1-yl, methimazolyl) with [Ru(X)Cl(CO)(PPh₃)_n] (n = 3 X = H; n = 2 BO₂C₆H₄, SiCl₃, SiMe₃) affords the complexes [Ru(X)(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}]. Evidence is presented to also support the transient formation of [Ru(X)(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}] (X = CHCHPh, Ph) via a similar strategy, although these are unstable. The osmium complex [OsH(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}] is similarly obtained from [OsHCl(CO)(PPh₃)₃] or [OsH(NCMe)₂(CO)(PPh₃)₂]BF₄. The reaction of [RuH(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}] with chloroform or diphenyldiselenide provides [Ru(X)(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}] (X = Cl, SePh), the latter reaction also providing traces of [Ru(SeH)(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}]. Spectroscopic and structural data for the series [Ru(X)(CO)(PPh₃){κ²-H,S,S′-H₂B(mt)₂}] are discussed in terms of perturbations on the B–H–Ru interaction by the trans-ligand X.