Coinage metal complexes with N'NN' and SeNSe ligands - Pincer vs bridging coordination pattern

The reactions of the ligands 2,6-(Me 2NCH 2) 2C 5H 3N (N'NN') (1) and 2,6-(PhSeCH 2) 2C 5H 3N (SeNSe) (4) with different coinage metal starting materials gave 1:1, 2:1 or 1:2 metal-to-ligand species, i.e. [Ag(N'NN'){O(O)CCF 3}] (2), [{Ag(PPh 3)} 2(N'NN')](OTf) 2 (3), [Au(SeNSe)Cl]Cl 2 (5), [Ag(PPh 3)(SeNSe)](OTf) (6), [Cu(MeCN)(SeNSe)](PF 6) (7) or [Cu(SeNSe) 2](PF 6) (8). The new compounds were investigated by IR, multinuclear NMR spectroscopies as well as mass spectrometry. In most cases, the ligands 1 and 4 act as pincer ligands. An attempt to grow single crystals of 2 gave an unexpected result. The crystal investigated by X-ray diffraction proved to be a polynuclear species, [Ag 4(N'NN'){O(O) CCF 3} 4(EtOH)] n (2a), which contains an unusual, bimetallic triconnective coordination pattern of the N'NN' ligand. Two tetranuclear [Ag 4(N'NN'){O(O)CCF 3} 4(EtOH)] units form centrosymmetric dimers further associated into a polymer which contains four different coordination environments around silver atoms. The complex 3, in which the ligand also exhibits a bimetallic triconnective pattern, shows an intense, long-lived luminescence in the solid state with emission energies in the green region of the visible spectrum. © 2012 Académie des sciences. des sciences. Published by Elsevier Masson SAS. All rights reserved.Financial support from the National University Research Council (CNCSIS, Romania; Research Project TD66/2007) and Ministerio de Economía y Competitividad (Spain, MEC/FEDER CTQ2010-20500-C02-01) is gratefully acknowledged.Peer Reviewe