Abstract
Chromium(II) chloride reacts with lithium pentamethylcyclopentadienide (LiCp*, Cp* C5Me5) and LiE(SiMe3)(2) (E = P or As) to give the heterocubane chromium phosphide [(eta(5)-Cp* Cr)(mu(3)-P)](4) (1) or the chromium arsenide cage [(eta(5)-Cp* Cr)(3)(mu(3)-As)(2)] (2), respectively. The crystal and molecular structures of both compounds have been determined by X-ray crystallography. The reactions ...
Abstract
Chromium(II) chloride reacts with lithium pentamethylcyclopentadienide (LiCp*, Cp* C5Me5) and LiE(SiMe3)(2) (E = P or As) to give the heterocubane chromium phosphide [(eta(5)-Cp* Cr)(mu(3)-P)](4) (1) or the chromium arsenide cage [(eta(5)-Cp* Cr)(3)(mu(3)-As)(2)] (2), respectively. The crystal and molecular structures of both compounds have been determined by X-ray crystallography. The reactions represent unusual oxidative additions of pnictogen atoms to chromium(II), which in the case of 1 results in the formation of the unusual chromium(IV) formal oxidation state, and in the case of 2 provides access to chromium(III). Compound 1 is also a rare example of a transition metal mu 3-phosphide-ligated cubane. Magnetic susceptibility and magnetization measurements, with support from DFT calculations, indicate S 2 and S 9/2 ground states for 1 and 2, respectively, which can be rationalized by considering the electronic structure in terms of chromium-chromium bonding.
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