Synthesis and crystal structure of a new salt of the complex anion [(TCNQ)3]2- [Mo2(μ2-S2)2(S2CNMe2)4](TCNQ)3

The reaction of compounds [Mo-2(mu(2)-S-2)(2)(S2CNR2)(4)] (BF4)(2) (1) (a R = Me, b R = Et) with 2 equiv, of LiTCNQ in methanol results in the formation of complexes [Mo-2(mu(2)-S-2)(2)(S2CNR2)(4)] (TCNQ)(2) (2). Further reaction of 2 with TCNQ yields the derivatives [Mo-2(mu(2)-S-2)(2)(S2CNR2)(4)] (TCNQ)(3) (3). Compounds 2 and 3 were characterized fully by microanalytical, IR and electron spin resonance studies. The single crystal structure of the green product 3a . 2 CH3CN was determined by X-ray diffraction methods. The TCNQ units form centrosymmetrical trimers with a slipped conformation and an interplanar distance of 3.16 Angstrom. In the [(TCNQ)(3)](2-) anion, the bond lengths agree with an almost complete delocalization of the charge between three essentially identical TCNQ units. The trimers stack with an intertrimer distance of 3.56 Angstrom. The centrosymmetric dinuclear cation is characterized by an Mo-Mo distance of 2.817(2) Angstrom in agreement with a metal-metal single bond. The molybdenum atoms are bridged by two mu(2)-S-2(2) - ligands which present a quite normal bridge distance S-S of 2.001(2) Angstrom. (C) 1998 Elsevier Science S.A. All rights reserved.