Nickel(II) macrocyclic complexes with long alkyl pendant chain: synthesis, x-ray structure, and anion exchange...

A nickel(II) pentaaza macrocyclic complex containing a 1-hexadecyl pendant chain, [Ni(C(25)H(55)N(5))](ClO(4))(2).H(2)O (1), was synthesized by a one-pot metal-template condensation reaction. Crystal data for 1: triclinic, Ponemacr;, a = 8.333(4) A, b = 8.356(3) A, c = 28.374(9) A, 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 ClO(4)(-) with NCS(-), PF(6)(-), C(2)O(4)(2-), NO(3)(-), and CF(3)SO(3)(-) that are dissolved in water. From the reaction of [Ni(C(25)H(55)N(5))Cl(2)] with Et(3)NH(TCNQ)(2) in EtOH/DMF/acetone solution, [Ni(C(25)H(55)N(5))(TCNQ)(2)](TCNQ).(CH(3)COCH(3)) (2) (TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) was prepared. Crystal data for 2: triclinic, Ponemacr;, a = 8.459(0) A, b = 13.945 (1) A, c = 26.833(2) A, 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-stacked 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-).