The [Cu 2(O 2CMe) 4(btd) 2] complex as a bridging unit: preparation, characterisation, X-ray structure and magnetism of the 2D coordination polymer {[Cu 6(O 2CMe) 8(OMe) 4(btd) 2]} n (btd=2,1,3-benzothiadiazole)

• Published in: Inorganica Chimica Acta 2001-12, Vol.326 (1), p.53-64
• Main Authors: Skorda, Konstantina, Papaefstathiou, Giannis S, Vafiadis, Anastasios, Lithoxoidou, Alexandra, Raptopoulou, Catherine P, Terzis, Aris, Psycharis, Vassilis, Bakalbassis, Evangelos, Tangoulis, Vassilis, Perlepes, Spyros P
• Format: Article
• Language: English
• Subjects: 2,1,3-Benzothiadiazole complexes; Acetate complexes; Copper(II) complexes; EPR spectra; Magnetic properties; Two-dimensional coordination polymers
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(01)00594-1

A systematic investigation of the [Cu 2(O 2CMe) 4(H 2O) 2]/btd reaction system is described, where btd=2,1,3-benzothiadiazole. Reaction of [Cu 2(O 2CMe) 4(H 2O) 2] with 5–8 equiv. of btd in both MeCN and MeOH yields [Cu 2(O 2CMe) 4(btd) 2] ( 1) in 40–50% yields. Treatment of [Cu 2(O 2CMe) 4(H 2O) 2] with 1.4 or 0.7 equiv. of btd in MeOH leads to the precipitation of the polymeric compound {[Cu 6(O 2CMe) 8(OMe) 4(btd) 2]} ( 2) in 82% yield. Reaction of 1 with two equivalents of [Cu 2(O 2CMe) 4(H 2O) 2] in MeOH under reflux provides an additional route to 2. The structure of 1 consists of centrosymmetric dinuclear [Cu 2(O 2CMe) 4(btd) 2] molecules of the paddle-wheel cage type. The two Cu II ions are bridged by four η 1:η 1:μ 2 acetates, while a monodentate btd is at the apex of the square pyramid of each metal centre. The 2D structure of 2 consists of chains of tetranuclear, planar Cu 4(OMe) 4(O 2CMe) 4 repeating units running along the a axis, which are connected along the cell body diagonal via Cu 2(O 2CMe) 4(btd) 2 paddle-wheel dinuclear units. The btd molecules behave as bidentate bridging ligands. Within the tetranuclear units, each Cu II ion is connected via two acetate bridges with one neighbouring Cu II ion and via two methoxo bridges with the other neighbouring Cu II ion; intertetranuclear linking is provided by two monoatomic acetate bridges. The results of solid state magnetic susceptibility studies are described for complex 2 in the temperature range 3–300 K. The results reveal antiferromagnetic exchange interactions between the Cu II ions. The complicated structure of 2 does not permit an exact treatment for the determination of the various exchange interactions. However, an approximate 3- J magnetic model was constructed, resulting in an excellent fit. An orbital interpretation of the J-trend derived is also attempted. [Cu 2(O 2CMe) 4(H 2O) 2] reacts with an excess of the potentially bidentate bridging N, N′-donor 2,1,3-benzothiadiazole (btd) to give the dinuclear, paddle-wheel complex [Cu 2(O 2CMe) 4(btd) 2]. This complex has two free coordination sites and serves as a bridging “ligand” for the construction of a structurally and magnetically interesting 2D copper(II) coordination polymer.