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Issue 17, 1997
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Triorganosiloxy and tetraphenyldisiloxydiolate complexes of the heavier alkaline-earth metals. Crystal structures of [Sr3(tmhd)3(OSiPh3)3] ·0.5C6H5Me (tmhd = 2,2,6,6-tetramethylheptane-3,5-dionate) and [Sr3{O(SiPh2O)2}3 (tetraglyme)2]·0.5C6H5Me [tetraglyme = CH3O(CH2CH2O)4CH3 ]

Abstract

Strontium or barium metal granules reacted with an excess of HOSiMe 2 Bu t in an ammoniacal toluene solution at -40 °C to produce the corresponding [M(OSiMe 2 Bu t ) 2 ] n . The strontium complex was also obtained from silanolysis of the strontium ethoxide [{Sr(OEt) 2 (HOEt) 4 } n ] with an excess of HOSiMe 2 Bu t in hot toluene solution. Similarly, the reaction of [{Sr(OEt) 2 (HOEt) 4 } n ] in hot toluene, with 1 molar equivalent of HOSiPh 3 and Htmhd (2,2,6,6-tetramethylheptane-3,5-dione) yielded the trimeric complex [Sr 3 (tmhd) 3 (OSiPh 3 ) 3 ] ·0.5C 6 H 5 Me. The reaction of strontium or barium metal granules with 2 molar equivalents of diphenylsilanediol [Ph 2 Si(OH) 2 ] in ammoniacal toluene solution at -40 °C yielded the polymeric complexes [{M[O(SiPh 2 O) 2 ](H 2 O)(NH 3 ) x } n ] [M = Ca (x = 0.3), Sr (x = 1) or Ba (x = 0.3)]. Similar reactions for strontium and barium in the presence of an excess of hmpa [OP(NMe 2 ) 3 ] produced [Sr 3 {O(SiPh 2 O) 2 } 3 (hmpa) 5 ]·C 6 H 5 Me and [Ba 3 {O(SiPh 2 O) 2 } 3 (hmpa) 5 (H 2 O)], respectively. Alternatively, when these reactions were performed in the presence of tetraglyme [CH 3 O(CH 2 CH 2 O) 4 CH 3 ] the water- and NH 3 -free complexes [M 3 {O(SiPh 2 O) 2 } 3 (tetraglyme) 2 ]·0.5C 6 H 5 Me were obtained (M = Sr or Ba). All complexes have been characterised by elemental analyses and IR, NMR ( 1 H, 13 C and 29 Si, in selected cases 31 P) spectroscopy and also by TGA/DSC studies. The complexes [Sr 3 (tmhd) 3 (OSiPh 3 ) 3 ] ·0.5C 6 H 5 Me and [Sr 3 {O(SiPh 2 O) 2 } 3 (tetraglyme) 2 ]·0.5C 6 H 5 Me have been characterised by X-ray crystallography. The structure of the former reveals a trimer of strontium cations stabilised by three tmhd ligands, and one µ- and two µ 3 -bridging triphenylsiloxy ligands. Relatively short Sr · · ·  C (methyl) and Sr · · ·  C (phenyl) contacts have also been identified in this compound. In contrast, the three strontium cations in the latter are arranged in an almost linear array within a Sr 3 O 9 Si 6 core.

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J. Chem. Soc., Dalton Trans., 1997, 2875-2886
Article type
Paper

Triorganosiloxy and tetraphenyldisiloxydiolate complexes of the heavier alkaline-earth metals. Crystal structures of [Sr3(tmhd)3(OSiPh3)3] ·0.5C6H5Me (tmhd = 2,2,6,6-tetramethylheptane-3,5-dionate) and [Sr3{O(SiPh2O)2}3 (tetraglyme)2]·0.5C6H5Me [tetraglyme = CH3O(CH2CH2O)4CH3 ]

I. Baxter, J. A. Darr, S. R. Drake, M. B. Hursthouse, K. M. Abdul Malik and D. Michael P. Mingos, J. Chem. Soc., Dalton Trans., 1997, 2875
DOI: 10.1039/A702960H

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