Polynuclear chromium(III) carboxylates. 1. Synthesis, structure, and magnetic properties of an octanuclear complex with a ring structure

Journal Article · Mon Apr 03 04:00:00 EDT 2000 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic9907009· OSTI ID:20050827

Eshel, M; Bino, A; Felner, I; Johnston, D C; Luban, M; Miller, L L

A novel cyclic octanuclear chromium(III) complex with hydroxo and acetato bridging ligands was isolated and its structure determined by X-ray crystallography. The complex [Cr{sub 8}(OH){sub 12}(OAc){sub 12}] (1) (OAc{sup {minus}} = CH{sub 3}CO{sub 2}{sup {minus}}), as found in crystals of 1{center_dot}34H{sub 2}O, is obtained by refluxing an aqueous solution of the trinuclear basic chromium acetate. 1{center_dot}34H{sub 2}O crystallizes in the tetragonal space group I{bar 4}2d with the following unit cell dimensions: a = 16.592(2) {angstrom}, c = 31.557(4) {angstrom}, V = 8687(1) {angstrom}{sup 3}, and Z = 2. A total of 2,000 unique data with I > 3{sigma}(I) were used to solve and refine the structure to R(F{sub o}) = 0.066 and R{sub w}(F{sub o}) = 0.085. The structure consists of eight Cr(III) ions that form a ring structure and are bridged by hydroxo and acetato ligands. Each of the two neighboring metal atoms in 1 is bridged either by two OH{sup {minus}} ligands and one OAc{sup {minus}} ligand, with a Cr{hor_ellipsis}Cr distance of 2.949(2) {angstrom}, or by two OAc{sup {minus}} ligands and one OH{sup {minus}} ligand, with a Cr{hor_ellipsis}Cr distance of 3.383(2) {angstrom} in an alternating fashion. The complex resides on a crystallographic 4 center, and the overall symmetry of 1 is S{sub 4}. The magnetic susceptibility of 1{center_dot}34H{sub 2}O was measured in the temperature range of 5--240 K. Theoretical modeling of the susceptibility data indicates alternating antiferromagnetic exchange interactions between adjacent spin 3/2 Cr{sup 3} ions around the ring, of magnitude J/k{sub B} = 13.7 and 8.9 K, respectively.

• Research Organization: Hebrew Univ. of Jerusalem (IL)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 20050827
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 7 Vol. 39; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBOXYLIC ACID ESTERS
CHROMIUM COMPLEXES
CRYSTAL STRUCTURE
HYDROXIDES
MAGNETIC PROPERTIES