The dinucleating macrocycles H2(Lm,n) containing two 2, 6-di(aminomethyl)-4-methylphenol entities combined through two alkane chains, -(CH2)m- (m=2, 3) and -(CH2)n- (n=2, 3, 4, 5), at the amine nitrogens, form nickel(II) complexes of the general formula [Ni2(Lm,n)(OAc)2] ((m, n)=(2,2), (2,4), (2,5), (3,3)) and [Ni2(L2,3)(OAc)(NCS)(CH3OH)]. [Ni2(L2.2)(OAc)2]·10H2O crystallizes in the triclinic system of space group P1 with a=9.983(2), b=12.832(2), c=7.932(1) Å, α=101.29(1), β=101.08(2), γ=106.57(2)°, V=921.1(3) Å3 and Z=1. The refinement converges with R=5.65 and Rw=5.89% based on 2308 reflections with |F0| > 3σ(|F0|). The macrocycle adopts a folded conformation and each nickel has a cis-β octahedral geometry with the N2O2 donor set of the macrocycle and two oxygens of a bidentate acetate group. The Ni-Ni separation bridged by two phenolic oxygens is 3.004 Å and the Ni-O-Ni angle is 95.6°. Cryomagnetic properties (4.2-300 K) of the complexes are well reproduced based on the spin Hamiltonian H=-2JS1·S2-D(Sz12-Sz22) with a positive exchange integral (J=+10.1 to +2.1 cm-1) and a negative zero-field splitting parameter (D=-0.53 to -2.40 cm-1). Each complex shows two reduction waves and two oxidation waves attributable to the metal centers.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry