The 7,7,8,8-Tetracyanoquinodimethane Salt of (C-meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II), [Ni(C-meso-Me6[14]aneN4)](TCNQ)2

The Maximin Principle of π-Radical Packings

“…This is substantiated by the smaller number of structures (ten) which adopt the staggered-short axis arrangement. 44,47,50,53,54,59,[61][62][63] This second arrangement, as it involves contacts between atoms all with large (although not the largest) HOMO presences, nonetheless seems a reasonable alternative.…”

“…The same procedure was adopted in our N-containing π-radical search except, of course, we allowed the presence of nitrogen atoms. The resulting data can be split in two groups: phthalocyanine (Pc) or related macrocycles, H 2 Pc, MPc, − and MPp 39-41 (we kept those Pc molecules coordinated to metal atoms, M), and nitrile derivatives, HCCP, , TCNQ, − DCNQI, BTCQ, and TCNE. − (See Supporting Information for CSD search results. Due to the large number of hits on TCNQ, only part of the TCNQ references are given here.)…”

“…We show for a number of N-containing π-systems that, from a knowledge of the HOMO or LUMO alone, we can correctly predict the most common crystal packing. π-Systems considered include all those N-containing systems with short C···C, C···N, or N···CN contacts (distances < 0.95 × the sum of the van der Waals radii): phthalocyanine (2HPc), metalated phthalocyanine (MPc), − metalated tetrabenzoporphyrin (MPp), − 1,2,3-tris(dicyanomethylene)cyclopropane (HCCP), , 7,7,8,8-tetra-cyanoquinodimethane (TCNQ), − N , N ‘-dicyano-1,4-benzoquinodiimine (DCNQI), 1,1,2,5,6,6-hexacyano-3,4-diazahexadiene (BTCQ), and tetracyanoethene (TCNE). − (See Supporting Information for CSD search results.) We further prepare two new phthalocyanine based cation radical salts which further verify the utility of the maximin principle.…”

Tetracyanoquinodimethanido Derivatives of (Terpyridine)‐ and (Phenanthroline)metal Complexes − Structural and Magnetic Studies of Radical‐Ion Salts

“…[6,8,13Ϫ15] When complexes with a fully coordinated metal environment are used, new species without direct bonding interactions between the metal and the TCNQ are formed. When TCNQ is fully reduced, dimerisation to [TCNQ] 2 2Ϫ is usually observed [7,8,16] but when TCNQ is partially reduced, a greater electronic delocalisation along with the formation of infinite stacks is observed.…”

“…[3,4] Special attention has been given to the assembly of organonitrile radical complexes with transition metals because of their rich interaction possibilities. One of the most extensively used radicals in these studies has been the planar organic molecule 7,7,8, since it shows a low reduction potential which makes it a suitable acceptor in charge transfer processes and also proposed. The compound [Fe(phen) 3 ](TCNQ) 2 , which shows a strong interaction between TCNQ anions, led to the formation of a σ bond in the diamagnetic species [TCNQ−TCNQ], while the nickel analogue is expected to have a localised structure formed by alternation of cationic metal complexes and dimeric [TCNQ] 2 2− anions similar to those observed in the analogous terpy derivatives.…”