Titanium/magnesium complexes: intermediates in the reduction of titanocene dichloride by magnesium
作者:Douglas W. Stephan
DOI:10.1021/om00038a081
日期:1992.2
(Cp2Ti(mu-Cl)2)2Mg(THF)2 (1) and (Cp2Ti(mu-Cl)2Mg(THF)2(mu-Cl)2)2 (2) have been isolated from the reaction of Cp2TiCl2 with Mg in THF and in the presence of P donors. A more convenient synthesis of 1 is derived from the reaction of (Cp2Ti(mu-Cl))2 with anhydrous MgCl2. These species have been structurally characterized. Complex 1 crystallizes in the monoclinic space group P2(1)/c with a = 8.104 (2) angstrom, b = 11.371 (4) angstrom, c = 16.282 (9) angstrom, beta = 91.53 (3)-degrees, Z = 2, and V = 1500 (1) angstrom 3, while compound 2 crystallizes in the tetragonal space group I41/a with a = 24.018 (6) angstrom, c = 14.927 (7) angstrom, Z = 8, and V = 8611 (5) angstrom 3. These species react with PMe3 to yield the Ti(III) species Cp2Ti(PMe3)Cl (3) and MgCl2. The species 3 reacts further with Mg in the presence of PMe3 to give the ''stabilized titanocene'' Cp2Ti(PMe3)2. These observations support the notion that Ti(III)/Mg compounds such as 1 and 2 are intermediates in the reduction of Cp2TiCl2 to Ti(II).
从Cp₂TiCl₂与Mg在THF中的反应(并加入P供体)中,分离出了化合物(Cp₂Ti(μ-Cl)₂)₂Mg(THF)₂(1)和(Cp₂Ti(μ-Cl)₂Mg(THF)₂(μ-Cl)₂)₂(2)。化合物1的更简便合成方法源于(Cp₂Ti(μ-Cl))₂与无水MgCl₂的反应。这些物质已通过结构表征。
化合物1在单斜晶系空间群P2(1)/c中结晶,晶格参数为a = 8.104(2)Å,b = 11.371(4)Å,c = 16.282(9)Å,β = 91.53(3)°,Z = 2,体积V = 1500(1)ų。而化合物2在四方晶系空间群I41/a中结晶,晶格参数为a = 24.018(6)Å,c = 14.927(7)Å,Z = 8,体积V = 8611(5)ų。
这些物质与PMe₃反应生成Ti(III)物质Cp₂Ti(PMe₃)Cl(3)和MgCl₂。物质3在PMe₃存在下进一步与Mg反应生成“稳定的二茂钛”Cp₂Ti(PMe₃)₂。
这些观察结果支持了Ti(III)/Mg化合物(如1和2)是Cp₂TiCl₂还原为Ti(II)过程中的中间体这一观点。