COMPLEXES CONTAINING HETERONUCLEAR AND HOMONUCLEAR QUADRUPLE BONDS - PREPARATION AND CHARACTERIZATION OF MOWCL4(DMPM)2 AND MO2X4(DMPM)2 (X = BR, I)
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The quadruply bonded heterobimetallic complex MoWCl4(dmpm)2 (1) and the homobimetallic complexes Mo2X4-(dmpm)2 (X = Br (2), I, (3)) were synthesized and their structures determined. The crystals of compound 1 exhibit the typical disorder for heteronuclear systems, namely, the random orientation of the M-M vector, with each metal atom appearing as 50% Mo and 50% W. The structural refinement in the space group P4 resulted in lower residuals, with R = 0.048 and Rw = 0.067, than in the space group P4/m. For complexes 2 and 3, crystals obtained from THF solutions are monoclinic, with space groups P21/c and P21/n for 2 and 3, respectively. The quadruple bond distances are 2.193(2), 2.1271(8), and 2.132(2) for 1, 2, and 3, respectively. In addition, each complex has been characterized using UV-visible, 31P{1H}) NMR, and 1H NMR spectroscopies. The average magnetic anisotropy of the Mo-Mo quadruple bond in complexes 2 and 3 has been calculated from 1H NMR data as 4450 1036 m3 molecule1. The crystal structures of complexes 13 are fully described, and their crystallographic data are as follows: (1) space group P4 with a = b = 9.083(2) , c = 8.092(2) , V 667.5(5) 3, and Z = 2; (2) space group P21/n with a = 8.694(1) , b = 8.695(2) , c = 15.369(2) , = 100.70(1), V= 1141.6(6) 3, and Z = 2; (3) space group P21/c with a = 9.076(2) , b = 16.813(7) , c = 16.654(5) , 102.4(1), V= 2481(4) 3, and Z = 4. 1993, American Chemical Society. All rights reserved.
