TY - JOUR
T1 - Polynuclear chromium(III) carboxylates. 1. Synthesis, structure, and magnetic properties of an octanuclear complex with a ring structure
AU - Eshel, Michal
AU - Bino, Avi
AU - Felner, Israel
AU - Johnston, David C.
AU - Luban, Marshall
AU - Miller, Lance L.
PY - 2000/4/3
Y1 - 2000/4/3
N2 - 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 [Cr8(OH)12(OAc)12] (1) (OAc- = CH3CO2-), as found in crystals of 1·34H2O, is obtained by refluxing an aqueous solution of the trinuclear 'basic' chromium acetate. 1·34H2O crystallizes in the tetragonal space group I4̄2d with the following unit cell dimensions: a = 16.592(2) Å, c = 31.557(4) Å, V= 8687(1) Å3, and Z = 2. A total of 2000 unique data with I > 3σ(I) were used to solve and refine the structure to R(F(o)) = 0.066 and RW(F(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- ligands and one OAc- ligand, with a Cr···Cr distance of 2.949(2) Å, or by two OAc- ligands and one OH- ligand, with a Cr···Cr distance of 3.383(2) Å, in an alternating fashion. The complex resides on a crystallographic 4̄ center, and the overall symmetry of 1 is S4. The magnetic susceptibility of 1·34H2O was measured in the temperature range of 5-240 K. Our theoretical modeling of the susceptibility data indicates alternating antiferromagnetic exchange interactions between adjacent spin 3/2 Cr3+ ions around the ring, of magnitude J/k(B) = 13.7 and 8.9 K, respectively.
AB - 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 [Cr8(OH)12(OAc)12] (1) (OAc- = CH3CO2-), as found in crystals of 1·34H2O, is obtained by refluxing an aqueous solution of the trinuclear 'basic' chromium acetate. 1·34H2O crystallizes in the tetragonal space group I4̄2d with the following unit cell dimensions: a = 16.592(2) Å, c = 31.557(4) Å, V= 8687(1) Å3, and Z = 2. A total of 2000 unique data with I > 3σ(I) were used to solve and refine the structure to R(F(o)) = 0.066 and RW(F(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- ligands and one OAc- ligand, with a Cr···Cr distance of 2.949(2) Å, or by two OAc- ligands and one OH- ligand, with a Cr···Cr distance of 3.383(2) Å, in an alternating fashion. The complex resides on a crystallographic 4̄ center, and the overall symmetry of 1 is S4. The magnetic susceptibility of 1·34H2O was measured in the temperature range of 5-240 K. Our theoretical modeling of the susceptibility data indicates alternating antiferromagnetic exchange interactions between adjacent spin 3/2 Cr3+ ions around the ring, of magnitude J/k(B) = 13.7 and 8.9 K, respectively.
UR - http://www.scopus.com/inward/record.url?scp=0034599287&partnerID=8YFLogxK
U2 - 10.1021/ic9907009
DO - 10.1021/ic9907009
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AN - SCOPUS:0034599287
SN - 0020-1669
VL - 39
SP - 1376
EP - 1380
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 7
ER -