Bis(η⁵-1,3-di-tert-butylcyclopentadienyl)chromium(II)

Abstract

The title compound, [Cr(C13H21)2] or [η5‐1,3‐(Me3C)2C5H3]2Cr, a substituted chromocene, crystallizes with two independent half‐molecules in the asymmetric unit, the molecules having twofold rotation symmetry. The compound is isostructural with the iron and cobalt analogues and is a bent metallocene.

Coordination chemistry of sterically encumbered pyrrolyl ligands to chromium(ii): mono(pyrrolyl)chromium and diazachromocene formation

“…For comparison, in the 1 H NMR spectrum of [(η 5 -1,3-(Me 3 C) 2 C 5 H 3 ) 2 Cr] the tBu-groups resonate at δ 0.2 (ν 1/2 = 250 Hz) and no methine resonances were found. 26 Furthermore, the UV/vis spectra of 1-Cr, 2-Cr and 3-Cr resemble each other closely, consistent with the notion that the pyrrolyl ligands 1-3 exhibit similar ligand field strengths (see ESI † for details).…”

“…[28][29][30] For 1-Cr and 2-Cr τ values are 0.97 and 1.00, respectively, suggesting complete electron delocalization. Furthermore, as expected from the NMR spectroscopy, the molecular structure of 1-Cr is closely related to that of the cyclopentadienyl derivative [(η 5 -1,3-(Me 3 C) 2 C 5 H 3 ) 2 Cr], 26 which shows a Cp(cent)-Cr distance of 1.81 Å. This bond distance is also similar to that 31 All these system complexes have an S = 1 ground state.…”

Preparation and Reactions of Base-Free Bis(1,3-di-tert-butylcyclopentadienyl)titanium, Cp′2Ti, and Related Compounds

“…The titanocene sublimes at 60–70 °C under diffusion pump vacuum, and it gives a molecular ion in the mass spectrum. Due to the flat-plate-like morphology of the titanocene crystals, and in spite of several attempts, no suitable crystals for an X-ray diffraction experiment were obtained …”