Mohanta, Sasankasekhar ; Nanda, Kausik K. ; Werner, Rudiger ; Haase, Wolfgang ; Mukherjee, Alok K. ; Dutta, Sujit K. ; Nag, Kamalaksha (1997) Macrocyclic CuII2, CuII4, NiII3, and NiII4 complexes: magnetic properties of tetranuclear systems Inorganic Chemistry, 36 (21). pp. 4656-4664. ISSN 0020-1669
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Official URL: http://pubs.acs.org/doi/abs/10.1021/ic9611103
Related URL: http://dx.doi.org/10.1021/ic9611103
Abstract
A binuclear tetraprotonated macrocyclic complex [Mg2(L2-H4)(NO3)2](NO3)2·6H2O (1) has been obtained by template condensation of 4-methyl-2,6-diformylphenol and 1,2-diaminoethane in the presence of magnesium acetate and nitrate. Complex 1 on reduction with NaBH4, followed by the removal of magnesium, yields the 36-membered octaaminotetraphenol macrocyclic ligand H4L1. The replacement of magnesium in 1 with copper(II) leads to the formation of the binuclear complex [Cu2L3(ClO4)2] (2) derived from the [2+2] cyclization product of 4-methyl-2,6-diformylphenol and 1,2-diaminoethane. From H4L1 a series of tetranuclear nickel(II) complexes 5-8 with the core cation [Ni4L1(μ2-X)2(μ2-H2O)2]2+ (X = NCS, N3, OAc, or Cl) have been synthesized and characterized. The trinuclear complex [Ni3L1(acac)2(H2O)2·2H2O (9), obtained by reacting nickel(II) acetylacetonate with H4L1, on treatment with nickel(II) perchlorate produces the tetranuclear compound [Ni4L1(acac)2(H2O)4](ClO4)2 (10). Variable-temperature (4-300 K) magnetic susceptibility measurements have been carried out for the tetracopper(II) complex [Cu4L1(H2O)4](ClO4)4 (3) and the tetranickel(II) complexes [Ni4L1(μ3-OH)(μ2-H2O)2(ClO4)](ClO4)2·2CH3COCH3·H2O (4), [Ni4L1(μ2-NCS)2(μ2-H2O)2](ClO4)2·2CH3CN (5), [Ni4L1(μ2-N3)2(μ2-H2O)2](ClO4)2·2CH3OH (6), [Ni4L1(μ2-OAc)2(μ2-H2O)2](ClO4)2·2H2O (7), and [Ni4L1(μ2-Cl)2(μ2-H2O)2]Cl2·4H2O (8). The X-ray structure of 5 has been determined. The complex (C50H70N12O14Cl2S2Ni4) crystallizes in the triclinic space group P with a = 11.794(6) Å, b = 12.523(4) Å, c = 12.794(5) Å, α = 117.28(5)°, β = 96.38(4)°, γ = 109.65(3)°, and Z = 1. In the asymmetric unit each of the nickel(II) centers with distorted octahedral geometry is triply-bridged by a phenoxide group, a water molecule, and a N-bonded thiocyanate and these metal centers are further bridged to their symmetry-related counterparts by another phenoxide group. The experimental susceptibility data have been analyzed using appropriate Heisenberg spin coupling models (H = -2 ∑4j>i=1 JijSi· Sj) and the best-fit spin exchange parameters obtained are as follows: J = -288(3) cm-1 (3); J1 = -8.1(2) cm-1, J2 = -10.2(2) cm-1 (4); J1 = -34.5(1.0) cm-1, J2 = -9.5(2.0) cm-1 (5); J1 = -34(1) cm-1, J2 = 11(2) cm-1 (6); J1 = -30(1) cm-1, J2 = -7.0(1.5) cm-1 (7); J1 = -32(1) cm-1, J2 = -4(1) cm-1 (8).
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to American Chemical Society. |
| ID Code: | 22629 |
| Deposited On: | 24 Nov 2010 08:07 |
| Last Modified: | 23 Jan 2011 15:47 |
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