3,4-Dimethyl-2,5-bis(trimethylsilyl)phospha- and 3,4-Dimethyl-2,5-bis(trimethylsilyl)arsacyclopentadienides of Calcium

Abstract

The reaction of zirconocene dichloride with 2 equiv of butyllithium and 1-trimethylsilylpropyne yields yellow 1,1-bis(cyclopentadienyl)-3,4-dimethyl-2,5-bis(trimethylsilyl)zirconacyclopenta-2,4-diene, 1. The metathesis reaction of 1 with PCl3 gives a mixture of 1-chloro- and 1-cyclopentadienyl-3,4-dimethyl-2,5-bis(trimethylsilyl)-1-phosphacyclopenta-2,4-diene, which was allowed to react in THF with distilled calcium. Crystallization of the product from THF solution gave dimeric bis(tetrahydrofuran-O)dicalcium bis[3,4-dimethyl-2,5-bis(trimethylsilyl)-1-phosphacyclopenta-2,4-dienide] cyclopentadienide chloride, 2. The metathesis reaction of 1 with AsCl3 yielded nearly quantitatively 1-chloro-3,4-dimethyl-2,5-bis(trimethylsilyl)-1-arsacyclopenta-2,4-diene, 3. 3,4-Dimethyl-2,5-bis(trimethylsilyl)-1-arsacyclopentadienyl bis(tetrahydrofuran-O)calcium chloride, 4, was isolated from the reduction of 3 with distilled calcium.

Phospha‐Organic Chemistry: Panorama and Perspectives

“…Stability is conferred upon the P ¼ C bond by the bulky siloxy and tert-butyl groups. A series of related syntheses relying on the reaction of bis(trimethylsilyl)phosphanes with phosgene, [23] CO 2 , [24] imino chlorides and dichlorides, [25] carbodiimides, [26] and CS 2 [267] are also based on the oxo-, aza-, and thiophilicity of silicon.…”

“…Recent additions include Ga, [257] Tl, [258] Hf, [259] Ge, [260] Sn, [260] Pb, [260] Cr, [261] Ir, [262] Nd, [263] and Tm. [264] In addition, several h 5 complexes of Group 1 and 2 metals have been structurally characterized, including Na, [265] K, [265] Cs, [266] Ca, [267] and Ba. [268] The chemistry of phosphaferrocenes and phosphacymantrenes has been studied in some detail.…”

Not Just Heavy “Grignards”: Recent Advances in the Organometallic Chemistry of the Alkaline Earth Metals Calcium, Strontium and Barium

“…(3) Necessary requirements for this reaction include the presence of highly active and pure alkaline earth metal. Activation methods include the distillation or sublimation of the metals, [29] the reduction of metal iodides with alkali metals, [30] or by dissolving the metals in anhydrous, deoxygenated liquid ammonia. [31] The reactivity of the metals plays a major role: barium will react smoothly, while the less reactive strontium and calcium generally require reflux conditions in liquid ammonia.…”

Synthesis of 2,2′,5,5′-Tetraphenyl-1,1′-diarsacalcocene and -strontocene

“…The reduction of 1-chloro-3,4-dimethyl-2,5-bis(trimethylsilyl)arsole yields the corresponding η 5 -bonded arsolide C. [3] However, only heteroleptic compounds were prepared and no dismutation reactions of 1,1Ј-dipentelametallocenes have been observed thus far. Scheme 1.…”

“…Schematic representation of the phospholides A and B, and the arsolide C proposed reaction mechanism explains the formation of the (iPr 3 Si) 2 As − and 2,5-diphenyl-3,4-bis(phenylethynyl)arsolide anions based on an intermolecular H/SiiPr 3 exchange reaction. The latter anion was characterized by X-ray crystallography with the binuclear cation [(THF) 3 Ca{µ-As(H)SiiPr 3 } 3 Ca(THF) 3 ] + (5). The arsolide ligands of 3 and 4 are η 5 -bonded to the metal centers, whereas 5 crystallizes as a solvent-separated ion pair.…”