PUB - Publikationen an der Universität Bielefeld

The reaction of the divalent metal halides ZnCl2, ZnBr2, MnCl2 . 4CH(3)CN, MnBr2, FeCl2 . 4CH(3)CN, CoCl2 . 4CH(3)-CN, CoBr2, NiCl2 . 6H(2)O, and NiBr2, respectively, with the macrocycle 1,4,7-trimethyl-1,4,7-triazacyclononane (L) (1:1) in anhydrous acetonitrile, acetone, chloroform, or ethanol affords upon addition of NaBPh4 the isomorphous series of complexes [LMII(u-X)(3)(ML)-L-II]BPh4: 1, M = Zn, X = Cl; 2, Zn, Br; 3, Mn, Cl; 4, Mn, Br; 5, Fe, Cl; 6, Co, Cl; 7, Co, Br; 5, Ni, Cl; 9, Ni, Br, Six of these complexes have been structurally characterized by single-crystal X-ray crystallography; they crystallize in the triclinic space group (No. 2) with Z = 4. Crystal data areas follows 1, a = 16.654(1), b = 17.042(1), c = 17.684(1) Angstrom, alpha = 97.30(1), beta = 93.58(1), gamma = 117.46(1)degrees; 3, a = 16.632(8), b = 17.012(8), c = 17.855(5) Angstrom, alpha = 97.16(3), beta = 93.37(3), gamma = 117.24(3)degrees; 5, a 16.658(3), b = 17.064(3), c = 17.741(4) Angstrom, alpha = 97.32(3), beta = 93.47(3), gamma = 117.36(3)degrees; 6, a = 16.640(3), b = 17.040(3), c = 17.686(4) Angstrom, alpha = 97.39(3), beta = 93.58(3), gamma = 117.39(3)degrees; 8, a = 16.608(3), b = 16.995(3), c = 17.555(3) Angstrom, alpha = 97.36(1), beta = 93.52(1), gamma = 117.52(1)degrees; 9, a 16.680(3), b = 17.016(2), c = 17.715(3)Angstrom, alpha = 96.99(1), beta = 93.70(1), gamma = 117.42(1)degrees. All complexes consist of a dinuclear, face-sharing bioctahedral monocation with three mu(2)-Cl or mu(2)-Br bridging Ligands and two LM fragments and well-separated tetraphenylborate actions (1:1). The cations cocrystallize in two different forms: an enantiomeric form with (lambda lambda lambda) (or (delta delta delta)) conformation at both LM fragments and a meso form with an (lambda lambda lambda) conformation at one LM fragment and (delta delta delta) at the other (ratio 1:1). From temperature-dependent magnetic susceptibility measurements (2-293 K) it was established that the spins of the unpaired electrons in 3 (d(5)d(5) high spin), 4 (d(5)d(5)), 6 (d(7)d(7) high spin), 7 (d(7)d(7)), 8 (d(8)d(8)), and 9 (d(8)d(8)) are intramolecularly, weakly antiferromagnetically coupled in each case. Surprisingly, the spins order ferromagnetically in 5 (d(6)d(6) high spin). This is in contrast to the previously reported complex [(thf)(3)-Fe-II(mu-Cl)(3)Fe-II(thf)(3)][SnCl5(thf)] (thf = tetrahydrofuran)(5) for which a new analysis of the temperature-dependence of the magnetic susceptibility and of field-dependent Mossbauer spectra establish a weak intramolecular antiferromagnetic coupling. The origin of this difference is analyzed.