RESUMEN
Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with MnCl2·4H2O, GdCl3·6H2O and 2,6-pyridinedimethanol (H2pdm) affords [MnIIIMnIIGdIII(H3L)(pdmH)(pdm)(MeOH)2(dmf)]·3MeCN·dmf (3·3MeCN·dmf) upon vapour diffusion of MeCN into the basic dmf/MeOH mother liquor. 3 crystallises in the tetragonal space group P41212 with the asymmetric unit comprising the entire cluster. The highly unusual core contains a triangular arrangement of MnIIIMnIIGdIII ions housed within a [MnIIIMnIIGdIII(OR)4]4- partial cubane. Magnetic susceptibility and magnetisation data reveal best fit parameters JMn(II)-Mn(III) = +0.415 cm-1, JMn(III)-Gd(III) = +0.221 cm-1, JMn(II)-Gd(III) = -0.258 cm-1 and DMn(III) = -4.139 cm-1. Theoretically derived magnetic exchange interactions, anisotropy parameters, and magneto-structural correlations for 3 are in excellent agreement with the experimental data.
RESUMEN
The synthesis, structural and magnetic characterisation of a family of homo- and heterometallic complexes constructed with the Schiff base ligands 2-iminomethyl-6-methoxy-phenol (L1H) and 2-imino-6-methoxy-phenol (L2H), are discussed. Members include the heterometallic tetranuclear complexes of general formula [Na2M2(X)2(L1)4(Y)2] (where M = Fe(III), X = (-)OMe, Y = NO3(-) (1) and M = Ni(II), X = N3(-) and Y = MeCN (2)), each possessing a butterfly-like topology. We also report the formation of the heterometallic molecular cage [Na3Ni2(L1)6](ClO4) (3) whose metallic skeleton describes a [rare] trigonal bipyramid, the homometallic 1-D coordination polymer [Mn(L1)2(Cl)]n (4), and the tetranuclear cubane clusters [Mn(III)3Mn(IV)(O)3(OEt)(OAc)3(L1)3] (5) and [Ni4(µ3-OMe)4(L2)4(MeOH)4] (6). Dc and ac magnetic susceptibility studies on complexes 5 and 6 reveal S = 9/2 and S = 4 spin ground states.
RESUMEN
The employment of di-2-pyridyl ketone, (py)2CO, in manganese(II) acetate chemistry is reported. The syntheses, crystal structures and magnetochemical characterisation are described for [MnII4(O2CMe)4{(py)2C(OH)O}4] () and [MnII10MnIII4O4(O2CMe)20{(py)2C(OH)O}4] (), where (py)2C(OH)O- is the monoanion of the gem-diol form of the ligand. The reaction of Mn(O2CMe)(2).4H2O with one equivalent of (py)2CO in Me2CO gives . Complex was obtained from the 1:1 reaction, in EtOH, between Mn(O2CMe)(2).4H2O and (py)2CO in the presence of NEt3. The tetranuclear molecule has a cubane topology with the MnII and the deprotonated oxygen atoms from the eta1:eta3:eta1:micro3 ligands occupying alternate vertices of the cube. The core of consists of two mixed valence cubane {MnII2MnIII2(micro3-O)2(micro3-OR'')2}4+ subunits that are linked through an unusual {MnII6(eta1:eta2:micro-O2CMe)6(eta2:eta2:micro3-O2CMe)2}4+ moiety via twelve eta1:eta1:micro MeCO2- groups. Some suggestions have been made concerning the possible assembly of from . The magnetic properties of in the 300-5 K range have been modelled with two J values, which reveal weak antiferromagnetic interactions within the molecule. Complex has a low spin ground state. This work demonstrates the flexibility, versatility and synthetic potential of combining (py)2CO with carboxylate ligands.