A base-free terminal thorium phosphinidene metallocene and its reactivity toward selected organic molecules

The stable base-free terminal phosphinidene thorium metallocene, [η5-1,2,4-(Me3C)3C5H2]2Th[double bond, length as m-dash]P-2,4,6-tBu3C6H2 (2), can be isolated from the reaction of the thorium dichloride complex [η5-1,2,4-(Me3C)3C5H2]2ThCl2 (1) with 2 equiv. of 2,4,6-(Me3C)3C6H2PHK in THF. The reactivity of 2 in the activation of various small organic molecules such as diselenides, phosphines, imines, ketones, phosphine oxides, thiazole, imidazole derivatives and amines was explored. For example, when complex 2 is treated with Ph2Se2, the phosphinidene is replaced, yielding diselenido compound [η5-1,2,4-(Me3C)3C5H2]2Th(SePh)2 (3). Moreover, E-H (E = P, N, C) bond activation occurs on exposure of 2 to 2,4,6-iPr3C6H2PH2, PhPH2, (p-tolyl)2C[double bond, length as m-dash]NH, 1-indanone, cyclohexanone, Me3PO, thiazole, 1-methylimidazole and p-toluidine, resulting in the phosphido complex [η5-1,2,4-(Me3C)3C5H2][η5,κ-C-1,2-(Me3C)2-4-(CH2CMe2)C5H2]Th(PH-2,4,6-iPr3C6H2) (4), the metallaheterocycle [η5-1,2,4-(Me3C)3C5H2]2Th(η2-P2Ph2) (5), the iminato phosphido complex [η5-1,2,4-(Me3C)3C5H2]2Th(PH-2,4,6-tBu3C6H2)[N[double bond, length as m-dash]C(p-tolyl)2] (6), the phosphido enolyl compound [η5-1,2,4-(Me3C)3C5H2]2Th(PH-2,4,6-tBu3C6H2)(κ-O-1-OC9H7) (7), the enolyl complex [η5-1,2,4-(Me3C)3C5H2][η5,κ-C-1,2-(Me3C)2-4-(CH2CMe2)C5H2]Th(κ-O-1-OC6H9) (8), the alkyl complex [η5-1,2,4-(Me3C)3C5H2][η5,κ-C-1,2-(Me3C)2-4-(CH2CMe2)C5H2]Th(κ-O,C-OPMe2CH2) (9), the phosphido thiazolyl complex [η5-1,2,4-(Me3C)3C5H2]2Th(PH-2,4,6-tBu3C6H2)(C3H2NS) (10), the bis-imidazolyl complex [η5-1,2,4-(Me3C)3C5H2]2Th[2-(1-MeC3H2N2)]2 (11), and the imido complex [η5-1,2,4-(Me3C)3C5H2]2Th[double bond, length as m-dash]N(p-tolyl) (12), respectively. Several spectroscopic techniques were employed for the characterisation of the new complexes 3-11, and in addition the solid-state molecular structures of compounds 3-6, 8-9 and 11 were further confirmed by X-ray diffraction analyses.