Estevan Francisco, Hirva Pipsa, Ofori Albert, Sanaú Mercedes, Špec Tanja, Úbeda MaAngeles
Departament de Química Inorgànica, Universitat de València , Dr. Moliner 50, 46100-Burjassot, València, Spain.
Department of Chemistry, University of Eastern Finland , Joensuu Campus, P.O. Box 111, FI-80101 Joensuu, Finland.
Inorg Chem. 2016 Mar 7;55(5):2101-13. doi: 10.1021/acs.inorgchem.5b02506. Epub 2016 Feb 25.
The versatility of pyrazole/pyrazolate as ligands has allowed the synthesis and the structural characterization of four different types of new orthometalated palladium compounds, for which DFT calculations have been performed in order to investigate their relative stabilities. [Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz)}2] (R = R' = H, 2a; R = Br, R' = H, 2b; R = CH3, R' = H, 2c; R = H, R' = CH3, 2d; R = Br, R' = CH3, 2e) compounds with exo-bidentate pyrazolatos are the first paddlewheel dinuclear palladium(II) compounds with pyrazolato bridging ligands described and characterized in the literature. In the process of the synthesis of 2a, a new tetranuclear intermediate compound, [Pd4{μ-(C6H4)PPh2}4(μ-pz)2(μ-OH)2] (3a), has been isolated and structurally characterized. Compounds of the general formula [Pd2{μ-(C6H4)PPh2}2Br2(R,R'2pzH)2] (R = R' = H, 4a; R = Br; R' = H, 4b; R = CH3; R' = H, 4c; R = H; R' = CH3, 4d; R = Br; R' = CH3, 4e) with pyrazoles as monodentate ligands have also been obtained, in which, according to the QTAIM analysis, additional Br···HNpz weak interactions stabilize their structure. The tetranuclear Pd2Ag2 compounds, [Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz-Ag-R,R'2pz)}2] (R = R' = H, 5a; R = Br; R' = H, 5b; R = CH3, R' = H, 5c), showed a distorted tetrahedron disposition of the metal atoms. The QTAIM analysis revealed an enhanced stability because of additional metal-metal interactions. New palladium(III) compounds, [Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz)}2Cl2] (R = R' = H, 6a; R = Br, R' = H, 6b) were also synthesized by oxidation of compounds 2 with PhICl2. DFT calculations highlighted their greater stability compared to that of similar compounds with N,N-donor ligands, such as formamidinatos and triazenidos.
吡唑/吡唑盐作为配体的多功能性使得四种不同类型的新型邻位金属化钯化合物得以合成和结构表征，为此进行了密度泛函理论（DFT）计算以研究它们的相对稳定性。[Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz)}2]（R = R' = H，2a；R = Br，R' = H，2b；R = CH3，R' = H，2c；R = H，R' = CH3，2d；R = Br，R' = CH3，2e）化合物带有外向双齿吡唑盐，是文献中描述和表征的首例带有吡唑盐桥连配体的桨轮双核钯（II）化合物。在合成2a的过程中，分离出了一种新的四核中间体化合物[Pd4{μ-(C6H4)PPh2}4(μ-pz)2(μ-OH)2]（3a）并对其进行了结构表征。还得到了通式为[Pd2{μ-(C6H4)PPh2}2Br2(R,R'2pzH)2]（R = R' = H，4a；R = Br；R' = H，4b；R = CH3；R' = H，4c；R = H；R' = CH3，4d；R = Br；R' = CH3，4e）的以吡唑为单齿配体的化合物，根据量子拓扑原子间相互作用（QTAIM）分析，额外的Br···HNpz弱相互作用稳定了它们的结构。四核Pd2Ag2化合物[Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz-Ag-R,R'2pz)}2]（R = R' = H，5a；R = Br；R' = H，5b；R = CH3，R' = H，5c）显示出金属原子的扭曲四面体排列。QTAIM分析表明由于额外的金属 - 金属相互作用稳定性增强。新型钯（III）化合物[Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz)}2Cl2]（R = R' = H，6a；R = Br，R' = H，6b）也通过用PhICl2氧化化合物2合成。DFT计算突出了它们与具有N，N供体配体（如甲脒盐和三氮烯盐）的类似化合物相比具有更高的稳定性。
