Synthese und Struktur von trimerem 1,5-Bis(p-ethoxyphenyl)pentaazadienidokupfer(I) — ein Komplex mit kurzen Cu—Cu-Kontakten in einer linearen Cu3 3+-Einheit / Synthesis and Structure of Trimeric 1,5-Bis(p-ethoxyphenyl)pentaazadienido-copper(I) — A Complex with Short Cu —Cu Contacts in a Linear Cu3 3+ Unit

Abstract

From a saturated solution of EtOC6H4N2NHN2C6H4OEt in aqueous ammonia and Cu(NH3)4 2+ dark brown Cu(EtOC6H4N5C6H4OEt)2 (1) is obtained as an explosive precipitate. Upon heating in pyridine 1 is reduced to trimeric 1,5-bis(p-ethoxyphenyl)pentaazadienido copper(I) (2). 2 forms air-stable red crystals with the rhombohedral space group R3̄̄ and the lattice constants a = 1371.2(4) pm, α = 86.88(3)° and Z = 2. In 2 a linear Cu3 3+ chain is coordinated by the atoms N 1, N 3 and N 5 of three pentaazadienido ligands, such that each Cu atom obtains a trigonal planar coordination by three N atoms. As 2 is located on the threefold axis of the space group R3̄̄, it has the Symmetrie C3. The distances Cu 2-N 3 = 192.7 pm to the more basic central atoms N 3 are shorter than the distances Cu 1-N 1 = 205.7 and Cu 3-N 5 = 201.5 pm to the outer N atoms of the N5 chains. The pentaazadienido ligand forms a planar N5 zig-zag chain with distances in the range of 127.8 to 135.4 pm. The very short Cu-Cu distances of 234.8 and 236.1 pm can be explained by bonding interactions between the d10 centers.