SYNTHESIS, STRUCTURE AND MAGNETIC-PROPERTIES OF [CU-5(BTA)(6)L-4] (BTA =BENZOTRIAZOLATE - L=BETA-DIKETONATE) CLUSTERS

Reaction of [CuL2] (LH: tfpbdH = 4,4,4-trifluoro-1-phenyl-1,3-butanedi one; tropH = tropolone; or acacH =acetylacetone; Ph/Me-pdH = I-phenyl- l,3-butanedionel Ph/Ph-pdH = 1,3-diphenyl-1,3-propanedione; or C4H3S/C F3-pdH =4,4,4-trifluoro-1-(2-thienyl-1,3-butanedione)) with benzotriaz ole (btaH) in CH2Cl2 yields the corresponding compound [Cu-5(bta)(6)L- 4] (L = tfpbd, 1; trop, 2; acac, 3; (Ph/Me-pd) 4 (Ph/Ph-pd) 5; (C4H3S/ CF3-pd) 6). The structures of 1 and 2 have been determined by single c rystal X-ray diffraction revealing a distorted tetrahedral arrangement of four Cu(II) centered on a fifth Cu(II). Each of the six bta ligand s spans an edge of the Cu, tetrahedron and is ligated to the central C u through its central nitrogen. Solid-state magnetic susceptibility st udies from 2-300 K have been accomplished for 1, 2 and 3 and reveal a weak antiferromagnetic intramolecular interaction between the five Cu( II) centres. The tridentate (mu(3)-bridging) bonding motif of bta is w ell suited for the formation of a protective monolayer of bta(-) ions on oxidised copper surfaces. Furthermore, the flexibility in this mode of coordination exhibited by bta(-) ions, as manifest within the stru ctures of 1, 2, and 3 (the structure of which was determined previousl y), is advantageous and would allow benzotriazolate to adapt to the va rious surface topographies which could well be presented by lightly ox idized copper surfaces. (C) 1998 Elsevier Science Ltd. All rights rese rved.