Two transition metal coordination polymers of the 7,7,8,8-tetracyanoquinodimethane dianion (TCNQ2−)

Abstract

Each of the two novel title transition metal coordination polymers, namely catena-poly[[bis{[tris(2-pyridylmethyl)amine]cobalt(II)}-mu(4)-7,7,8,8-tetracyanoquinodimethanide(2-)] bis[7,7,8,8-tetracyanoquinodimethanide(1-)] methanol disolvate], {[Co(2)(C(12)H(4)N(4))(C(18)H(18)N(4))(2)](C(12)H(4)N(4))(2).2CH(3)OH}(n), (I), and catena-poly[[[[tris(2-pyridylmethyl)amine]iron(II)]-mu(2)-7,7,8,8-tetracyanoquinodimethanide(2-)] methanol solvate], {[Fe(C(12)H(4)N(4))(C(18)H(18)N(4))].CH(3)OH}(n), (II), contains eta(4)-TPA and cis-bridging TCNQ(2-) ligands [TPA is tris(2-pyridylmethyl)amine and TCNQ is 7,7,8,8-tetracyanoquinodimethane], but the two compounds adopt entirely different structural motifs. Compound (I) consists of a ribbon coordination polymer featuring mu(4)-TCNQ(2-) radical anion ligands bridging four different octahedral Co(II) centers. Each formula unit of the polymer is flanked by two uncoordinated TCNQ(-) anions and two methanol solvent molecules. All three TCNQ anions have crystallographic inversion symmetry. In (II), the 2(1) symmetry operator generates a one-dimensional zigzag chain of octahedral Fe(II) centers with mu(2)-TCNQ(2-) bridges. A methanol solvent molecule forms hydrogen bonds to one of the terminal N atoms of the bridging TCNQ(2-) dianion. To the best of our knowledge, these are the first examples of one-dimensional coordination polymers forming from cis coordination of two TCNQ ligands to octahedral metal centers.