Magneto-structural variety of new 3d-4f-4(5)d heterotrimetallic complexes

摘要

Three families of heterotrimetallic chains (type 1-type 3), with different topologies, have been obtained by reacting the 3d-4f complexes, [{Cu(L-1)}(x)Ln(NO3)(3)] with x = 1 or 2, formed in situ by the reaction of Schiff-base bi-compartmental [Cu-II(L-1)] complexes and lanthanide(III) salts, with (NHBu3)(3)[M(CN)(8)] (M = Mo-V, W-V). For type 1 series of compounds, 1-D coordination polymers, with the general formula [{Cu-2(valpn)(2)Ln}{M (CN)(8)}]center dot nH(2)O center dot mCH3CN (where H(2)valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol), result from the association of trinuclear {Cu(2)(II)Ln(III)} moieties and [MV(CN)(8)](3-) anions acting as tri-connecting spacers [Ln = La (1), Ce (2), Eu (3), Tb (4), Ho (5), M = Mo; Ln = Tb (6), Ho (7), M = W; m = 0, n = 1.5 (7) and 2 (1-4, 6); n = 1, m = 1 (5)]. The type 2 family has the general formula [{Cu(valdp)Ln(H2O)(4)}{M(CN)(8)}]center dot 2H(2)O center dot CH3CN (where H2valdp = 1,2-propanediylbis(2-iminomethylene-6-methoxy-phenol)) and also consists of heterotrimetallic chains involving binuclear {Cu(II)Ln(III)} units linked to [M(CN)(8)](3-) anions coordinating through two cyano groups [Ln = Gd (8), Tb (9), Dy (10); M = Mo; Ln = La (11), Gd (12), Tb (13), Dy (14); M = W]. With large Ln(III) ions (La-III and Pr-III), the type 3 family of heterotrimetallic compounds are assembled: [{Cu-2(valdp)(2)Ln(H2O)(4)}{Mo(CN)(8)}]center dot nCH(3)OH center dot mCH(3)CN, n, m = 0, Ln = La (15); n = m = 1, Pr (16), in which the trinuclear {Cu(2)(II)Ln(III)} nodes are connected to [Mo-V(CN)(8)](3-) anions that act as tetra-connecting spacers. For Tb-III derivatives of the type 1 (compounds 4 and 6), the DC magnetic properties indicate a predominant ferromagnetic Cu-II-Tb-III interaction, while the AC magnetic susceptibility (in the presence of a static magnetic field, HDC = 3000 Oe) emphasize the slow relaxation of the magnetization (U-eff/k(B) = 20.55 K and tau(0) = 5.5 x 10(-7) s for compound 4, U-eff/k(B)T = 15.1 K and tau(0) = 1.5 x 10(-7) s for compound 6). A predominant ferromagnetic CuII-LnIII interaction was also observed in the type 2 series (compounds 8-10 and 12-14) as a result of the magnetic coupling between copper(II) and lanthanide(III) ions via the phenoxo-bridge. The magnetic behavior for the La-III derivatives reveals that weak ferromagnetic interactions are also operative between the CuII and the 4d/5d centers.