| Abstract: | Two equivalents of K[Cp′] (Cp′=C5(i-Pr)3H2, C5(i-Pr)4H, C5(t-Bu)2H3) react with CrCl2 in THF to give the corresponding chromocenes, Cp′2Cr, in good yield. Despite the presence of bulky substituents on the rings that could affect their properties, the complexes are extremely air- and moisture-sensitive, and possess a low-spin ground state. The low-spin paramagnetic nature of each chromocene was confirmed by magnetic susceptibility measurements. The solid-state structure of [C5(i-Pr)3H2]2Cr was obtained using single crystal X-ray analysis. It displays rigorously parallel rings, with an average Cr–C(ring) distance of 2.17(1)Å; the chromium resides on a crystallographically imposed inversion center. The orientation of the isopropyl groups minimizes unfavorable steric interactions between the rings. |
