Cu(II) and Ag(I) complexes of the pyrazole-derived diorganoselenide (pzCH2CH2)2Se. Synthesis, solid state structure and solution behavior

The diorganoselenide (pzCH2CH2)2Se (R2Se (1), pz = pyrazole) was prepared by reacting the in situ obtained Na2Se with 1-(2-bromoethyl)-1H-pyrazole in a water/ethanol mixture. Copper(II) and silver(I) complexes of type [CuX2{Se(CH2CH2pz)2}] [X = Cl (2), Br (3), NO3 (4), ClO4 (5)] and [AgX{Se(CH2CH2pz)2}] [X = OTf (6) (OTf = CF3SO3), NO3 (7), ClO4 (8)] were obtained by reacting the ligand 1 with the appropriate copper(II) and silver(I) salt in 1:1 molar ratio. The ligand and the metal complexes were investigated by appropriate spectroscopic methods, both in solution and in solid state: multinuclear NMR (1H, 13C, 19F, 77Se), UV–Vis spectroscopy, ESI mass spectrometry, IR spectroscopy and molar conductivity. The metal complexes 2, 3 and 6–8 behave as 1:1 electrolytes in solution, while 4 and 5 behave as 1:2 electrolytes. The molecular structures of complexes [CuX2{Se(CH2CH2pz)2}] [X = Cl (2), Br (3), NO3 (4)], [Cu(ClO4)2{Se(CH2CH2pz)2}(H2O)] (5⋅H2O) and [AgOTf {Se(CH2CH2pz)2}] (6) were determined by single-crystal X-ray diffraction. The (pzCH2CH2)2Se ligand acts as a N, Se,N chelating moiety in 2, 3, 4 and 5⋅H2O and as a bridging, tetraconnective 2 × N,Se unit in 6.