Interaction of bis(1,2,6,7-tetracyano-3,5-dihydro-3,5-diiminopyrrolizinide) metal complexes with phenazine and derivatives. Crystal structures of addition compounds of the nickel(II) complex with phenazine and 5,10-dimethyl-5,10-dihydrophenazine

Abstract

The charge-transfer compounds of the electron-acceptor moiety [NiL₂](L = 1,2,6,7-tetracyano-3,5-dihydro-3,5-diiminopyrrolizinide) and the electron-donating phenazine derivatives [phenazine (phz), 5,10-dimethyl-5,10-dihydrophenazine (dmphz) and N-methylphenazinium cation (mphz⁺)] have been synthesized and characterized. The X-ray crystal structures of [NiL₂]˙2phz˙2MeCN 1a and [NiL₂]˙dmphz˙2MeCN 1b have been determined. Both compounds are monoclinic, mixed-stacked compounds, with planar acceptor and donor moieties alternating along the c axis [1a: space group P2₁/n, a= 14.687(1), b= 21.364(2), c= 7.8208(6)Å, β= 110.958(6)°, Z= 2; 1b: space group P2₁/c, a= 12.975(5), b= 19.838(7), c= 7.651(3)Å, β= 106.05(2)°, Z= 2]. While 1a, as expected, does not show any solid-state collective property, 1b is a semiconductor (single crystal ρ= 3.6 × 10³Ω cm at room temperature; E_a= 0.28 eV); its degree of ionicity gradually increases, on lowering the temperature, from zero to a small amount corresponding to an effective magnetic moment (µ_eff)= of 0.28 µ_B per molecular formula. The cobalt derivative [CoL₂]˙dmphz˙2MeCN has also been synthesized and characterized, which is isomorphous and isostructural with the nickel analogue, and qualitatively behaves likewise (single crystal ρ= 4.2 × 10⁵Ω cm at room temperature; E_a= 0.26 eV); its magnetic measurements show a highspin metal configuration (S=, µ_eff= 4.13 µ_B). The N-methylphenazinium (mphz⁺) derivative, isolated as [NiL₂]˙^–˙mphz⁺˙2MeOH, is assumed to be a mixed-stacked radical anion salt from magnetic (µ_eff= 1.72 µ_B) and electrical (powder ρ= 5.5 × 10⁶Ω cm at room temperature, E_a= 0.43 eV) measurements.