TTF based charge transfer salts of [Cr(NCS)(4)(phen)](-): bulk magnetic order and crystal structures of the TTF, TMTTF (tetramethyltetrathiafulvalene) and TMTSF (tetramethyltetraselenafulvalene) derivatives

A series of new charge transfer salts of electron donors based on tetrathia fulvalene, TTF, with the anion [Cr(NCS)(4)(phen)](-) (phen=1,10-phenanthrol ine) have been prepared. Single crystal X-ray diffraction provided structur es for salts with donors TTF, TMTTF, tetramethyltetrathiafulvalene, and TMT SF, tetramethyltetraselenafulvalene. The salts were found to be [TTF][Cr(NC S)(4)(phen)] at 293 K, [TMTTF][Cr(NCS)(4)(phen)]. CH2Cl2 at 250 K and [TMTS F](3)[Cr(NCS)(4)(phen)](2). 0.5CH(2)Cl(2) at 293 K. For the TMTSF compound the solvent is disordered at 293 K so the structure was also solved at 120 K when the solvent becomes ordered. All of the salts have multiple S ... S or S ... Se close contacts between the anions and cations. The TTF salt is a bulk ferrimagnet with T-c=9 K and is an insulator whereas the TMTTF salt is an antiferromagnetic (T-N=3.0 K) insulator. Both have close atomic inter actions of the phen-donor pi-stacking type, but the TMTTF salt also contain s close anion-anion contacts and dimerised cations whereas the TTF salt con sists of stacks of alternating cations and anions. The TMTSF salt is a para magnetic semiconductor and does not display pi stacking but has close inter -donor Se ... Se contacts and isolated anions which afford the magnetic and transport properties.