Fluxional rhodium scorpionate complexes of the hydrotris(methimazolyl)borate (Tm) ligand and their static boratrane derivativesCCDC reference numbers 761317–761321. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c000651c

The reaction of potassium hydrotris(methimazolyl)borate {KTm = HB(mt)3} with [{Rh(cod)(μ-Cl)}2] gave [Rh(cod)Tm] while the complexes [Rh(CO)(PR3)Tm] (R = Ph or NMe2) and [Rh{P(OPh)3}2Tm] were isolated from light-sensitive [Rh(CO)2Tm], prepared in situfrom KTm and [{Rh(CO)2(μ-Cl)}2], and PR3or P(OPh)3under CO. The complexes [Rh(cod)Tm] and [Rh(CO)(PR3)Tm] (R = Ph or NMe2) adopt κ3-S2Hstructures in the solid state but in all cases rapid dynamic exchange processes render the three mt rings equivalent in solution. Oxidation of [Rh(CO)(PPh3)Tm] with [Fe(η-C5H5)2][PF6] in the presence of NHPri2gave a mixture containing two monocationic rhodaboratranes. One is assigned as [Rh(CO)(PPh3){B(mt)3}][PF6] on the basis of IR and NMR spectroscopy, with boron transto the phosphine ligand. The second, structurally characterised as [Rh(PPh3){B(mt)3}][PF6], has boron transto an empty coordination site, vacated by CO. Similar oxidation of [Rh(cod)Tm] gave small quantities of the boron-fluorinated bis(scorpionate) [Rh{FB(mt)3}2][PF6]. [ABSTRACT FROM AUTHOR]