Replacement of the Common Chromium Source CrCl(3)(thf)(3) with Well-Defined [CrCl(2)(μ-Cl)(thf)(2)](2)

CrCl(3)(thf)(3) is a common starting material in the synthesis of organometallic and coordination compounds of Cr. Deposited as an irregular solid with no possibility of recrystallization, it is not a purity guaranteed chemical, causing problems in some cases. In this work, we disclose a well-defined form of the THF adduct of CrCl(3) ([CrCl(2)(μ-Cl)(thf)(2)](2)), a crystalline solid, that enables structure determination by X-ray crystallography. The EA data and XRD pattern of the bulk agreed with the revealed structure. Moreover, its preparation procedure is facile: evacuation of CrCl(3)·6H(2)O at 100 °C, treatment with 6 equivalents of Me(3)SiCl in a minimal amount of THF, and crystallization from CH(2)Cl(2). The ethylene tetramerization catalyst [iPrN{P(C(6)H(4)-p-Si(nBu)(3))(2)}(2)CrCl(2)](+)[B(C(6)F(5))(4)](−) prepared using well-defined [CrCl(2)(μ-Cl)(thf)(2)](2) as a starting material exhibited a reliably high activity (6600 kg/g-Cr/h; 1-octene selectivity at 40 °C, 75%), while that of the one prepared using the impure CrCl(3)(thf)(3) was inconsistent and relatively low (~3000 kg/g-Cr/h). By using well-defined [CrCl(2)(μ-Cl)(thf)(2)](2) as a Cr source, single crystals of [(CH(3)CN)(4)CrCl(2)](+)[B(C(6)F(5))(4)](−) and [{Et(Cl)Al(N(iPr)(2))(2)}Cr(μ-Cl)](2) were obtained, allowing structure determination by X-ray crystallography, which had been unsuccessful when the previously known CrCl(3)(thf)(3) was used as the Cr source.