Magnetically isolated Cu(II)Gd(III) 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(salicylideniminate(-)), hfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate(-), pta = 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionate(-)].
[Cu(salen)Gd(pta)(3)] (1), [Cu(acacen)Gd(pta)(3)] (2), and [Cu(acacen)Gd(hfa)(3)] (3) are three heterobimetallic [Cu(II)Gd(III)] 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 Cu(II) and chelates Gd(III) 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-dionate(-)]. They crystallize as a triclinic structure (space group P). The cell parameters are a = 9.8616(10) A, b = 12.1976(13) A, c = 18.4187(22) A, alpha = 90.671(14) degrees, beta = 100.588(13) degrees, gamma = 103.684(12) degrees, V = 2113 A(3), and Z = 2 for 1; a = 9.7560(11) A, b = 12.2924(13) A, c = 18.9368(22) A, alpha = 88.449(14) degrees, beta = 87.269(14) degrees, gamma = 67.629(12) degrees, V = 2098 A(3), and Z = 2 for 2; and a = 12.5726(15) A, b = 15.5985(18) A, c = 18.3724(21) A, alpha = 85.963(13) degrees, beta = 85.411(14) degrees, gamma = 80.766(14) degrees, V = 3539 A(3), and Z = 4 for 3. The Cu(O,O')Gd bridging cores show folding angles about O,O' in the range 139 degrees -147 degrees and intramolecular Cu small middle dot small middle dot small middle dotGd distances of about 3.3 A. 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) A for 1, 4.831(1) A for 2, and 4.511(1) and 3.868(1) A 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 [Cu(II)Gd(III)] complexes, including [Cu(salen)Gd(hfa)(3)] (4) (Ramade, I.; Kahn, O.; Jeannin, Y.; Robert, F. Inorg. Chem. 1997, 36, 930-936).
Ryazanov
M
M
Moscow State University, Department of Chemistry, Leninskie Gory, 119899 Moscow, Russia.
Nikiforov
V
V
Lloret
F
F
Julve
M
M
Kuzmina
N
N
Gleizes
A
A