| Abstract
| - The transmetalation of bis[(trimethylsilyl)methyl]zinc with distilled strontium and barium yielded the corresponding alkaline-earth-metal bis{tris[(trimethylsilyl)methyl]zincates} containing M−C−Zn three-center−two-electron bonds. The zincate anions coordinate as bidentate ligands to the metal centers.
- The transmetalation of bis[(trimethylsilyl)methyl]zinc in THF with distilled strontiumand barium yielded bis(tetrahydrofuran)strontium and tetrakis(tetrahydrofuran)barium bis{tris[(trimethylsilyl)methyl]zincates} (1 and 2, respectively). The reaction of barium withZn(CH2SiMe3)2 in toluene gave bis(η6-toluene)barium bis{tris[(trimethylsilyl)methyl]zincate}(3) with rather short Ba−C bond lengths of 3.028(5) and 3.055(5) Å. All of these trialkylzincateanions coordinate as bidentate ligands with M−C−Zn three-center two-electron bonds. Whencarried out in the nondonor solvent heptane, the transmetalation reaction yielded bariumbis{tris[(trimethylsilyl)methyl]zincate} (4), which reacts with THF to give the complex 2and a small amount of [(THF)3Ba]2(μ4-O)2[(Me3SiCH2ZnCH2)2SiMe2]2 (5). The central moietyis a centrosymmetric Ba2O2 cycle with Ba−O distances of 2.514(2) and 2.570(3) Å. The oxygendianion is surrounded, distorted tetrahedrally by two barium and two zinc atoms.
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