Synthesis and magnetic properties of 1:1 salts containing the bis(η⁶-hexamethylbenzene)cobalt cation

Abstract

The salts [ C O ( ~~-C , M ~, ) ~] +[A] -(A = BPh,, NbF,, PF, or SbF,) have been prepared from anhydrous CoCI,. Solid-state magnetic susceptibility measurements on these salts indicate that they all obey the

Access to the Bis‐benzene Cobalt(I) Sandwich Cation and its Derivatives: Synthons for a “Naked” Cobalt(I) Source?

“…Separate determination of the spin and orbital magnetic moments of 1 + (g) , as possible by XMCD, reveals a non‐vanishing orbital contribution to μ eff of 0.2 μ B . Thus, the values obtained for 1 + (g) and 1 + / 2 + [A] − are within the range of previously reported values for the isoelectronic d 8 complexes Co(hmb) 2 + (magnetic balance (MB): 2.95, SQUID: 2.6–2.8), Ni(hmb) 2 2+ (MB: 3.00) and Fe(hmb) 2 0 (MB: 3.08 μ B ) and are in good agreement with the expected triplet state. The detected orbital magnetic moment of the cation 1 + (g) indicates spin‐orbit coupling and is in line with the observation of a zero‐field splitting (ZFS) in the samples of 1 + / 2 + [A] − .…”

“…[3] Subsequent attempts to isolate Co(arene) 2 + complexes with arenes other than the very electron rich hmb (e.g.,w ith mesitylene, [2] toluene, [4] bz [4,5] )f ailed. Va rious Co(hmb) 2 + salts were the subject of further studies [6,7] and served for the synthesis of novel Co I compounds,for example,with dienes. [8,9] However, only one hmb ligand could be displaced and the fragment (hmb)Co + was always incorporated.…”

New Synthetic Pathway to Mono- and Bis-indenyl Complexes of Molybdenum(IV)

“…The more relevant contributions comprise the structural systematics of indenyl distortion along the family of sandwich derivatives Ind 2 M (M ) Fe, Co, Ni) 4 and the ready addition of CO to Ind 2 V in eq 2. 5 In the case of group 6 metals the only known bisindenyl derivatives are (C 9 Me 7 ) 2 Cr, 6 (η 5 -Ind)W(η 3 -Ind)-(CO) 2 , 7 (η 5 -Ind)Mo(η 3 -Ind)(CO) 2 , 2a and (η 5 -Ind)Mo(η 3 -Ind)(dppe). 8 However, (η 5 -Ind)Mo(η 3 -Ind)(CO) 2 is difficult to prepare, and its W congener was obtained in a reported 1.5% yield.…”

Determination of Large Zero-Field Splitting in High-Spin Co(I) Clathrochelates

“…The limited number of Co­(I) complexes whose ZFS has been studied differ substantially in structure so that a comparison with our present complex is not meaningful. In general, D / hc values ranging from −180 to +38 cm –1 have been found. − Both experimentally and computationally, the rhombic anisotropy parameter E was determined here to be zero. This arises from the symmetry of the first ligation shell, where the Co­(I) ion lies on a pseudo- C 3 axis (there is some slight deviation from the ideal C 3 symmetry) .…”

“…In this context, Co complexes attract significant attention. They oftentimes exhibit very large magnetic anisotropies and have been successfully used as building blocks in single-molecule magnets. , However, clear-cut correlations between the magnetic properties and the atomic and electronic structure are in their infancy. ,, Furthermore, studies have been in most cases dedicated to Co­(II), but very little is known about their Co­(I) counterparts. − …”