Becker, G. Crystal structures and spectroscopic properties of 2 λ3 phospha-1,3-dionates and 1,3-dionates of calcium - comparative studies on the 1,3-diphenyl- and 1,3-Di(tertbutyl) derivatives

Becker, G., Niemeyer, M., Mundt, O., Schwarz, W., Westerhausen, M., Ossberger, M.W., Mayer, P., Nöth, H., Zhong, Z., Dijkstra, P.J. and Feijen, J

Zeitschrift für anorganische und allgemeine Chemie 630, 2605-2621

A hydrogen-metal exchange between dibenzoylphosphane and calcium carbide in tetrahydrofuran (THF) followed by addition of the ligand 1, 3, 5-trimethyl-1, 3, 5-triazinane (TMTA) furnishes the binuclear complex bis[(tmta-N, N, N)calcium bis(dibenzoylphosphanide)] (1a) co-crystallizing with benzene. Similarly, reaction of bis(2, 2-dimethylpropionyl)phosphane with bis(thf-O)calcium bis[bis(trimethylsilyl)amide] in 1, 2-dimethoxyethane (DME) gives bis(dme-O, O)calcium bis[bis(2, 2-dimethylpropionyl)phosphanide] (1b) in high yield. The carbon analogues 1, 3-diphenylpropane-1, 3-dione (dibenzoylmethane) or 2, 2, 6, 6-tetramethylheptane-3, 5-dione (dipivaloylmethane) and bis(thf-O)calcium bis[tris(trimethylsilylmethyl)zincate] in DME afford bis(dme-O, O)calcium bis(dibenzoylmethanide) (2a) and the binuclear complex (-dme-O, O)bis[(dme-O, O)calcium bis(dipivaloylmethanide)] (2b), respectively. Dialkylzinc formed during the metalation reaction shows no reactivity towards the 1, 3-dionates 2a and 2b. Finally, from the reaction of the unsymmetrically substituted ligand 2-(methoxycarbonyl)cyclopentanone and bis(thf-O)calcium bis[bis(trimethylsilyl)amide] in toluene, the trinuclear complex 3 is obtained, co-crystallizing with THF. The -ketoester anion bridges solely via the cyclopentanone unit.