A DIMERIC CALCIUM SILOXIDE LIGHTLY STABILIZED BY AMMONIA LIGANDS

The reaction of calcium granules with Ph(3)SiOH in an ammoniacal-toluene solution at -40 degrees C produces the complex [Ca-2(OSiPh(3))(4)(NH3)(4)(NH3)(4)].0.5C(7)H(8)(1), and reaction of compound 1 with thf at room temperature yields [Ca(OSiPh(3))(2)-(thf)]n (2). These two compounds were characterized by IR and (?)1H, C-13, and Si-29 NMR spectroscopy, DSC, and TGA, and the structure of complex 1 was determined by single-crystal X-ray crystallography. The molecule consists of a dimeric calcium motif with one terminal and three mu(2)-bridging triphenylsiloxide ligands. The ammonia groups all occupy terminal coordination sites, resulting in asymmetric five- and six-coordinate calcium centers. Crystallographic data for 1 at 150 K: monoclinic space group P2(1)/c, a = 15.483(7) Angstrom, b = 22.407(5) Angstrom, c = 20.231(7) Angstrom, beta = 98.18(2)degrees, V = 6947.28 Angstrom(3), Z = 4.