Unexpectded behaviour of copper (I) towards a tridentate Schiff base: synthesis, structure and properties of new Cu(I)-Cu(II) and Cu(II) complexes

摘要

The reaction of CuBr with 2,6-bis[2,6-diisopropylphenylimino)ethyl] pyridine L afforded a new Cu(I)-Cu(II) derivative [CuBrL]_2Cu_2Br_4(1) while the reaction of [Cu(CH_3CN)_4]PF_6 with L in THF yielded the new Cu(I) compound CuL(THF)(CH_3CN)PF_6(2). Derivative 2 further reacter with halogenated solvents to yield halogneno-Cu(II) salts, [CuClL]PF_6(3) using CHCl_3 and [CuBrL]Br_3(4) using CHBr_3. Compounds 1,3 and 4 have been fully characterised by X-ray crystallography; they contain essentially similar [CuXL]~+ cations with a square planar copper (II) co-ordination. However, the structure of compound 1 must be viewed as built of tetranuclear units since two [Cu~(II)BrL]~+ cations are bridged by a [Cu_2~IBr_4]~(2-) anion with a rather strong Cu(II)…A） secondary interaction . These secondary interactions (Cu(II) cation … FPF_5 or Br anion are weaker in 3 and 4. The electrochemical properties of compounds 1-4 are discussed. too.