Abstract
The prepn., mass spectra, and structures of Re2(PhN)2CMe2Cl4 (I) and Re2(MeN)2CPh4Cl2.CCl4 (II) are reported. I crystallizes in the monoclinic space group P21/n with a 14.774(4), b 12.008(4), c 16.990(5) \AA, b 92.78°, V = 3002(3) \AA3, and Z = 4. The mols. occupy general positions within the cell and have a rotational conformation that is twisted -3.8° from the perfectly eclipsed conformation. The Re-Re bond length is 2.178(1) \AA, and the Re-Cl and Re-N distances are 2.314(7) (av.) and 2.06(2) \AA (av.), resp. II crystallizes in the tetragonal space group I4/mmm with a 14.235(2), c 12.199(2) \AA, V = 2472(1) \AA3, and Z = 4. The Re-Re and Re-Cl bond lengths are 2.208(2) and 2.654(6) \AA, resp. The structure of I is very similar to that previously found for Re2(PhN)2CPh2Cl4, as would be expected. II is of interest because the Me groups keep the axial Cl- ligands at a greater distance than for the Re2(O2CR)4Cl2 compds. (R = Ph, CMe3) which have Re-Cl $\approx$ 2.48 \AA. The Re-Re distance in II is significantly shorter (by 0.022 \AA) than in the carboxylato compds., thus showing again the effect of axial ligands in weakening M-M quadrupole bonds as well as the ability of the N and N' substituents in amidinato, triazinato, and amidato ligands to restrict access to the axial positions. on SciFinder(R)
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