Reactivity of cyclopentadienyl transition metal(II) complexes with borate ligands: Structural characterization of the toluene-activated molybdenum complex [Cp∗Mo(CO)<inf>2</inf>(η³-CH<inf>2</inf>C<inf>6</inf>H<inf>5</inf>)]

Reactions of cyclopentadienyl transition-metal halide complexes [Cp∗Mo(CO)3Cl], 1, and [CpFe(CO)2I], 2, (Cp = C5H5; Cp∗ = η5-C5Me5) with borate ligands are reported. Treatment of 1 with [NaBt2] (Bt2 = dihydrobis(2-mercapto-benzothiazolyl)borate) in toluene yielded [Cp∗Mo(CO)2(C7H4S2N)], 3, and [Cp∗Mo(CO)2(η3-CH2C6H5)], 4, with a selective binding of toluene through C-H activation followed by orthometallation. Note that compound 4 is a structurally characterized toluene-activated molecule in which the metal is in η3-coordination mode. Under similar reaction conditions, [NaPy2] (Py2 = dihydrobis(2-mercaptopyridyl)borate) produced only the mercaptopyridyl molybdenum complex [Cp∗Mo(CO)2(C5H4SN)], 5, in good yield. On the other hand, when compound 2 was treated individually with [NaBt] (Bt = trihydro(2-mercapto-benzothiazolyl)borate) and [NaPy2] in THF, formation of the η1-coordinated complexes [CpFe(CO)2(C7H4S2N)], 6, and [CpFe(CO)2(C5H4SN)], 7, was observed. The solid-state molecular structures of compounds 3, 4, 6, and 7 have been established by single-crystal X-ray crystallographic analyses.