Synthesis of Strontium and Barium Bis{tris[(trimethylsilyl)methyl]zincates} via the Transmetalation of Bis[(trimethylsilyl)methyl]zinc

Abstract

The transmetalation of bis[(trimethylsilyl)methyl]zinc in THF with distilled strontium and barium yielded bis(tetrahydrofuran)strontium and tetrakis(tetrahydrofuran)barium bis-{tris[(trimethylsilyl)methyl]zincates} (1 and 2, respectively). The reaction of barium with Zn(CH 2 SiMe 3 ) 2 in toluene gave bis(η 6 -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 trialkylzincate anions coordinate as bidentate ligands with M-C-Zn three-center two-electron bonds. When carried out in the nondonor solvent heptane, the transmetalation reaction yielded barium bis{tris[(trimethylsilyl)methyl]zincate} (4), which reacts with THF to give the complex 2 and a small amount of [(THF) 3 Ba] 2 (µ 4 -O) 2 [(Me 3 SiCH 2 ZnCH 2 ) 2 SiMe 2 ] 2 (5). The central moiety is a centrosymmetric Ba 2 O 2 cycle with Ba-O distances of 2.514(2) and 2.570(3) Å. The oxygen dianion is surrounded, distorted tetrahedrally by two barium and two zinc atoms.

Recent Advances in the Chemistry of Metallacarboranes

“…In the highly ionic solvated Ba(BH 4 ) 2 the boranate anions coordinate via three H atoms to the alkaline earth metal atom, thus forming three-center BaϪHϪB bonds. [56] The BaϪC distances are similar to those of barium bis[tris(trimethylsilylmethyl)zincates] [57] where bridging trimethylsilylmethyl moieties between barium and zinc atoms were found. The BaϪC distances of substituted barocenes vary between 2.90 and 3.00 Å .…”

Alkyl Abstraction from a Trialkylyttrium Complex [YR3(thf)2] (R = CH2SiMe3) Using a Group‐13 Element Lewis Acid ER3 (E = B, Al, Ga, In) – Structural Characterisation of the Ion Pair [YR2(thf)4]+[GaR4]– and of ER3 (E = B, Al, Ga)

“…[10] NMR spectroscopic analysis of these compounds showed that all alkyl groups are chemically and magnetically equivalent on the NMR timescale and an equilibrium between neutral alkyl complexes, "ate" complexes, contact ion pairs and solvent separated ions was proposed in the literature. [10][11][12] A further example for solvent dependence of the structures and for intra-/intermolecular exchange was reported for [La(η 5 -(E = Ga, 2b; In, 2c), as was observed for 1a. The peaks arising from the cationic yttrium species are similar in all three cases, implying only weakly coordinating anions.…”

Heavy Grignard Reagents: Challenges and Possibilities of Aryl Alkaline Earth Metal Compounds

“…[70] However, decomposition into [MA C H T U N G T R E N N U N G (CH 2 SiMe 3 ) 2 ] and [ZnA C H T U N G T R E N N U N G (CH 2 SiMe 3 ) 2 ] was neither possible by changing the solvent nor by using high temperatures. Therefore, a more noble metal than zinc was chosen and phenyl copper was treated with activated calcium in THF according to Scheme 11.…”