53 - J . A m . Chem. SOC.1987, 109, 5703-57 1 1 m etal...

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J. Am. Chem. SOC. 1987, 109, 5703-57 11 5703 Supplementary Material Available: Tables of crystal data, atom coordinates, thermal parameters, bond distances and angles, and hydrogen coordinates (1 1 pages); listings of structure factors (34 pages). Ordering information is given on any current masthead metal carbonyl moiety in the end on fashion is probably a result of steric factors. Acknowledgment. We thank the National Science Foundation for financial support. page. Preparation and Physical Properties of Trinuclear Oxo-Centered Manganese Complexes the General Formulation [Mn30(02CR)6L3]09+ (R = Me or Ph; L = a Neutral Donor Group) and the Crystal Structures [ Mn30(02CPh)6(pyr)2(H20)]*0.5MeCN [Mn,0(02CMe>6(pyr)3](pyr) and John B. Vincent,t Hsiu-Rong Chang,s Kirsten Folting,t John C. Huffman,* George Christou,*t and David N. Hendrickson*§ Contribution from the Department of Chemistry and the Molecular Structure Center, Indiana University, Bloomington. Indiana 47405, and the School of Chemical Sciences, University of Illinois, Urbana, Illinois 61 801, Received October 15, 1986 Abstract: The reaction of N-n-Bu4Mn04 with appropriate reagents in nonaqueous solvents leads to the high-yield formation of trinuclear oxo-centered Mn complexes of general formulation [Mn30(02CR)6L3]z+ (1, R = Me, L = pyr, z = 1; 2, = = pyr, z = 0, monopyridine solvate; 3, = Me, L = pyr, z = 0, unsolvated; 4, = Ph, L3 = (pyr),(H20), z = 0; 5, R = = HIm, z = 1; pyr = pyridine, HIm = imidazole). The crystal structures of complexes 2 and 4 have been determined. Complex 2 crystallizes in rhombohedral space group R32 with (at -50 "C) a = b = 17.552 (6) A, c = 10.918 (3) A, y = 120.00 (1)O, and Z = 3. A total of 1546 unique data with F > 3u(F) were refined to conventional values of R R, of 5.77 and 5.86%, respectively. Complex 4 crystallizes in monoclinic space group P2, with (at -156 "C) a = 15.058 (IO) b = 23.600 (17) 8, c = 14.959 (10) fl = 91.01 (3)", and Z = 2. A total of 7174 unique data with F > 3a (6 were refined to values of R of 8.64 and 8.43%, respectively. Both 2 4 possess an oxo-centered Mn,O unit characteristic of "basic carboxylates" with peripheral ligation provided by bridging carboxylate and terminal pyr (or H20) groups. Each Mn is distorted octahedral, and consideration of overall charge of the trinuclear units necessitates a mixed-valence Mn"Mn2" description. In 2, the presence of a C3 axis through the central 0 and perpendicular to the Mn30 unit necessitates the Mn centers to be crystallographically equivalent, suggesting rapid intramolecular electron transfer or electronic delocalization. In contrast, 4 possesses no imposed symmetry elements and is in a trapped-valence situation in accord with its mixed-ligand nature, since two Mn centers have a terminal pyr group while the third Mn has a terminal H20 molecule. The latter metal center is assigned as the Mn" ion based on its longer metal-ligand distances. Variable temperature solid state magnetic susceptibility studies have been performed on 1-4 in the temperature range of -6 to -340 K. Satisfactory fits to the observed susceptibility data have been obtained by assuming isotropic magnetic exchange interactions and employing the appropriate spin Hamiltonians and derived susceptibility equations. All
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53 - J . A m . Chem. SOC.1987, 109, 5703-57 1 1 m etal...

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