Magnetically isolated (CuGdIII)-Gd-II pairs in the series [Cu(acacen)Gd(pta)(3)], [Cu(acacen)Gd(hfa)(3)], [Cu(salen)Gd(pta)(3)], and [Cu(salen)Gd(hfa)(3)], [acacen = N,N '-ethylenebis(acetylacetoniminate(-)), salen = N,N '-ethylenebis(salicylidenimin

摘要

Cu(salen)Gd(pta)(3)] (1), [Cu(acacen)Gd(pta)(3)] (2), and [Cu(acacen)Gd(hfa)(3)] (3) are three heterobimetallic [(CuGdparallel to)-Gd-parallel to] complexes of general formula [Cu(SB)Gd(beta-dik)(3)], in which a N,N',O,O' Schiff base (SB) ligand [acacen = N,N'-ethylenebis(acetylacetoniminate(-)), salen = N,N'-ethylenebis(salicylideneiminate(-))] tetracoordinates Cull and chelates Gd-parallel to as a tris(beta-diketonate) complex [hfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate(-); pta = 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dlonate(-)]. They crystallize as a triclinic structure (space group F). The cell parameters are a = 9.8616(10) Angstrom, b = 12.1976(13) Angstrom, c = 18.4187(22) Angstrom, alpha = 90.671(14)degrees, beta = 100.588(13)degrees, 103.684(12)degrees, V 2113 Angstrom(3), and Z = 2 for 1; a = 9.7560(11) Angstrom, b = 12.2924(13) Angstrom, c = 18.9368(22) Angstrom, 88.449(14)degrees, beta = 87.269(14)degrees, gamma = 67.629(12)degrees, V = 2098 Angstrom(3), and Z 2 for 2; and a = 12,5726(15) Angstrom, b 15.5985(18) Angstrom, c = 18.3724(21) Angstrom, a = 85.963(13)degrees, beta = 85.411(14)degrees, gamma = 80.766(14)degrees, V = 3539 Angstrom(3), and Z = 4 for 3. The Cu(O,O')Gd bridging cores show folding angles about O,O' in the range 139degrees-147degrees and intramolecular Cu...Gd distances of about 3.3 Angstrom. In the solid state, the molecules form centrosymmetric pseudodimers [Cu(SB)Gd(beta-dik)(3)](2), through the overlap of the Cu(SB) entities. Resulting intradimer Cu...Cu distances are 5.941(1) Angstrom for 1, 4.831 (1) Angstrom for 2, and 4.511 (1) and 3,868(1) Angstrom for 3 which comprises two symmetrically independent dimers. The temperature dependence of complexes 1-3 was investigated in the range 1.8-300 K and revealed weak ferromagnetic interactions, Results are discussed in light of the structural features and of available magnetostructural data for other heterobimetallic [(CuGdparallel to)-Gd-parallel to] complexes, including [Cu(salen)Gd(hfa)(3)] (4) (Ramade, I.; Kahn, C.; Jeannin, Y.; Robert, F. Inorg. Chem. 1997, 36, 930-936). [References: 29