Chemistry and supramolecular chemistry of chromium horseshoes

Abstract

Synthetic and structural studies of Cr horseshoes are reported which show that these compounds demonstrate a rich supramolecular chemistry through H-bonding interactions, and can act as ligands for metal clusters.

Heterometallic Rings: Their Physics and use as Supramolecular Building Blocks

“…[27] Reaction of 24 with sodium azide or sodium isocyanate gives [{CrNa 14 F 6 (H 2 O) 10 }(H 2 NEt 2 ){Cr 6 F 11 -(O 2 C t Bu) 12 } 4 ]( 30;F igure 12). [27] Reaction of 24 with sodium azide or sodium isocyanate gives [{CrNa 14 F 6 (H 2 O) 10 }(H 2 NEt 2 ){Cr 6 F 11 -(O 2 C t Bu) 12 } 4 ]( 30;F igure 12).…”

“…[27] Compounds 24-27 are therefore clearly part of af amily of horseshoes with the chromium fragments having the general [27] Compounds 24-27 are therefore clearly part of af amily of horseshoes with the chromium fragments having the general…”

“…, which forms aone-dimensional H-bonded polymer in the crystal. [27] Compounds 24-27 are therefore clearly part of af amily of horseshoes with the chromium fragments having the general…”

“…Reaction with s-or f-block metal complexes is more interesting. [27] Reactions with lanthanide pivalate complexes give ar ange of compounds that seem sensitive to the size of the lanthanide ion. [29] Reaction of 24 with cerium pivalate gives [Cr 6 CeF 7 (O 2 C t Bu) 14 (THF) 2 ]( 31;F igure 13);t his is only the second heptanuclear ring reported [30] and the structure is clearly related to the octa-, nona-, and decanuclear rings described above.Afluoride and two carboxylates bridge each edge of the structure.T he cerium site is eight-coordinate, bound to two THF molecules,derived from the recrystallization solvent.…”

Synthesis and Structural, Magnetic and EPR Characterization of Discrete Finite Antiferromagnetic Chains

“…AF chain complexes-discrete, finite open structures-are much rarer [8], but their physics has also been of interest in, for example, understanding the nature of magnetic ground states and excitations in spin clusters, and termination effects in 1-D AF materials. We recently reported {Cr n III } AF chains of formula [Cr n F n?5 (O 2 CCMe 3 ) 2n-2 ] 3-(n = 3, 6 and 7) [8,9], and their magnetic properties as probed by magnetic susceptibility, electron paramagnetic resonance (EPR) and inelastic neutron scattering (INS). Families such as these are particularly important since they allow detailed comparison of different chain lengths of otherwise identical species.…”