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Highly symmetric enneanuclear copper(II) phosphates [Cu9(Pz)6(μ-OH)3(μ3-OH)(ArOPO3)4(DMF)3] (PzH = pyrazole, Ar = 2,6-(CHPh2)2-4-R-C6H2; R = Me, 2MeAr; Et, 2EtAr; iPr, 2iPrAr; and Ar = 2,6-iPr2C6H3, 2Dip) comprising nine copper(II) centers and pyrazole, hydroxide and DMF as ancillary ligands were synthesized by a reaction involving the arylphosphate monoester, 1, copper(I)chloride, pyrazole, and triethylamine in a 4 : 9 : 6 : 14 ratio. All four complexes were characterized by single crystal structural analysis. The complexes contain two distinct structural motifs within the multinuclear copper scaffold: a hexanuclear unit and a trinuclear unit. In the latter, the three Cu(II) centres are bridged by a μ3-OH. Each pair of Cu(II) centers in the trinuclear unit are bridged by a pyrazole ligand. The hexanuclear unit is made up of three dinuclear Cu(II) motifs where the two Cu(II) centres are bridged by an –OH and a pyrazole ligand. The three dinuclear units are connected to each other by phosphate ligands. The latter also aid the fusion of the trinuclear and the hexanuclear motifs. Magnetic studies reveal a strong antiferromagnetic exchange between the Cu(II) centres of the dinuclear units in the hexanuclear part and a strong spin frustration in the trinuclear part leading to a degenerate ground state.

Two new polynuclear complexes of Cu(II), [(μ-1,1,3-N3)2{Cu2(me2tn)2(N3)2}]n (1) (me2tn=2,2-dimethylpropane-1,3-diamine) and [Cu2(μ-C2O4)(μ-N3)(ipr2en)2]n(ClO4)n (2) (ipr2en=N,N′-di-isopropylethane-1,2-diamine) have been synthesized and structurally characterized by X-ray crystallography. The crystal structure of 1 displays a 2D network in which distorted octahedral copper(II) centers, chelated by a me2tn ligand and bound to a terminal azide, are connected through μ-1,1,3 bridging azide anions. The structure of 2 shows 1D chains comprising alternating [(ipr2en)Cu-Ox-Cu(ipr2en)] units and end-to-end azide ligand. The chains on mutual H-bonding interaction through ClO4 −, give rise to a 2D supramolecular architecture. The magnetic data of complexes were recorded in the temperature range, 300–2 K. In case of complex 1, the magnetic data are consistent with a ferromagnetic interaction through the end-on azide bridge (JFM=10 cm−1) and a weak antiferromagnetic interaction (zj=−0.8 cm−1) between the ferromagnetically coupled dimers and an average g-value of 2.05. The susceptibility data of 2 were fitted using an alternating AF–AF chain spin 1/2 law which leads to the following parameters Joxalate=−180 cm−1, Jazide=−43 cm−1 and g=2.25 cm−1.