Synthesis and Characterization of Novel Oxo-Bridged Dinuclear and Hydroxo-Bridged Trinuclear Chromium(III) Assemblies.
The structural and spectroscopic properties of a novel dinuclear chromium-oxo and a trinuclear chromium-hydroxo complex are reported. The dinuclear assembly, [Cr(2)(&mgr;-O)(2)(&mgr;-O(2)CMe)(bpy)(2)(H(2)O)(2)]ClO(4).bpy.[bpyH]ClO(4) (1), crystallizes in the monoclinic space group Cc with a = 16.8259(8) Å, b = 21.9622(11) Å, c = 14.6056(8) Å, beta = 122.1830(10) degrees, V = 4568.0(4) Å(3), and Z = 4. The structure was refined with 4378 observed reflections having F > 2.0sigma(F), giving final R factors of 0.0721 and 0.1305 for R and R(w2), respectively. The [Cr(2)(&mgr;-O)(2)(&mgr;-O(2)CMe)](+) core is structurally akin to those of recently reported isoelectronic [Mn(2)(&mgr;-O)(2)(&mgr;-O(2)CMe)](3+) complexes. The trinuclear assembly, [Cr(3)(&mgr;-OH)(2)(&mgr;-O(2)CMe)(4)(O(2)CMe)(2)(bpy)(2)]ClO(4) (2).5CHCl(3) crystallizes in the triclinic space group P&onemacr; with a = 16.104(5) Å, b = 17.623(5) Å, c = 12.236(3) Å, alpha = 93.33(1) degrees, beta = 92.81(1) degrees, gamma = 64.84(1) degrees, V = 3136.68 Å(3), and Z = 2. The structure was refined with 6732 observed reflections having F > 2.33sigma(F), giving final R factors of 0.0602 and 0.0616 for R and R(w), respectively. Results of electronic, (1)H and (2)H NMR, and EPR spectroscopy, fast atom bombardment mass spectrometry, and variable-temperature magnetic susceptibility studies of these materials and the use of Cr-oxo assemblies as isoelectronic models of the photosynthetic manganese assembly in high-S states are discussed.
Harton
Anthony
A
Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487-0336, Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, Department of Chemistry, Washington University, St. Louis, Missouri 63130, and Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148.
Terrell
Katisha
K
Huffman
John C.
JC
MacDonald
Chris
C
Beatty
Alicia
A
Li
Sichu
S
O'Connor
Charles J.
CJ
Vincent
John B.
JB