Synthesis and characterization of the P,C-palladacycles with bridging and chelating dinitrogen ligands and ONIOM calculations on the pyrazine-bridged organometallic polymers (n=1 to n=10)

In this report we investigated the reaction of bromo-bridged cyclopalladated complex of tri-o-tolylphosphine with aromatic and aliphatic bidentate N-donor ligands (pyrazine, 4,4'-bipyridine, 1,2-bis(4pyridyl) ethane, 1,3-bis(4-pyridyl) propane, ethylenediamine). These reactions lead to the new P, C-palladacycles which were fully characterized by IR, NMR spectroscopies and CHN analysis. Interestingly, the linear organometallic polymer with a zig-zag manner was obtained and determined by X-ray crystallography in which the pyrazine rigid molecules act as the bridging ligands between Pd(II) centres. To understand the reason of this polymerization process, two layers ONIOM (QM: QM) calculations were performed on the organometallic polymer [Pd(P(o-tolyl)(3))(pyrazine)](n) (n = 1 to 10) in order to study the stability trend of polymer as a function of size (n). The infrared (IR) spectrum of the [Pd(P(o-tol-yl)(3))(pyrazine)](n) was calculated for different values of n and its evolution with the size of polymer was observed. The shapes of HOMO, LUMO and the energy gap between them were also studied with increasing n. (C) 2016 Elsevier B. V. All rights reserved.