Nickel(II) macrocyclic complexes with long alkyl pendant chain: Synthesis, X-ray structure, and anion exchange property in the solid state

A nickel(II) pentaaza macrocyclic complex containing a 1-hexadcyl pendant chain, [Ni(C25H55N5)]ClO4)(2).H2O (1), was synthesized by a one-pot metal-template condensation reaction. Crystal data for 1: triclinic, P1, a = 8.333(4) Angstrom, b = 8.356(3) A, c = 28.374(g) Angstrom, alpha = 81.865(19)degrees, beta = 86.242(18)degrees, gamma = 63.871(17)degrees, Z = 2. Solid 1 forms hydrophobic layers that are constructed by the long alkyl chains of the macrocycles. Solid 1 exchanges ClO4- with NCS-, PF6-, C2O42-, NO3-, and CF3SO3- that are dissolved in water. From the reaction of [Ni(C25H55N5)Cl-2] with Et3NH(TCNQ)(2) in EtOH/DMF/acetone solution, [Ni(C25H55N5)(TCNQ)(2)](TCNQ).(CH3COCH3) (2) (TCNQ = 7,7,8,8tetracyano-p-quinodimethane) was prepared. Crystal data for 2: triclinic, P1, a = 8.459(0) Angstrom, b = 13.945 (1) A, c = 26.833(2) Angstrom, alpha = 88.744(2)degrees, beta = 84.536(2)degrees, gamma = 80.089(4)degrees, Z = 2. In 2, TCNQ anions coordinate nickel(II) at the axial sites, which form pi-stackecl TCNQ(-) dimers to give rise to 1-D chains. The neutral TCNQ molecules are included between the dimerized TCNQ- species, which construct a pi-stacked group of six TCNQ units as blocked by the long alkyl chains. Compound 2 is an electric insulator. It shows a weak signal in the EPR spectrum. The magnetic susceptibility data of 2 measured at 5-300 K exhibit a simple paramagnetism at low temperatures (<100 K) but an increase in the magnetic moment at higher temperatures due to the contribution of a thermally accessible triplet state for the antiferromagnetically coupled [TCNQ](2)(2-).