Synthesis and ligand substitution reactions of κ4-B,S,S',S''-ruthenaboratranes.

A range of ruthenaboratranes of the form [Ru(CO)L{κ4-B,S,S',S''-B(mt)3}] (mt = N-methylmercaptoimidazolyl) have been prepared either by substitution of the PPh3 ligand in [Ru(CO)(PPh3){κ4-B,S,S',S''-B(mt)3}] by L (L = PMe2Ph, PMe3, P(OMe)3, P(OEt)3, P(OPh)3) or reactions of [RuCl(R)(CO)Ln] (R = Ph, CH[double bond, length as m-dash]CHPh; n = 2, L = PCy3; n = 3, L = P(OMe)3, PMe2Ph) with Na[HB(mt)3].

Dihydrobis(methimazolyl)borato complexes of ruthenium and osmium.

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 = CH[double bond, length as m-dash]CHPh, 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.

Caveats for poly(methimazolyl)borate chemistry: the novel inorganic heterocycles [H2C(mt)2BR2]Cl (mt = methimazolyl; BR2 = BH2, BH(mt), 9-BBN).

Whilst frequently used for reactions of poly(methimazolyl)borates, dichloromethane is not an innocent solvent, but rather slowly forms heterocyclic salts [H(2)C(mt)(2)BR(2)]Cl, three examples of which (BR(2) = BH(2), BH(mt), 9-borabicyclononyl) have been structurally characterised to confirm the unprecedented B(NCS)(2)C connectivity.