Solution, Solid, and Gas Phase Studies on a Nickel Dithiolene System: Spectator Metal and Reactor Ligand

详细信息    查看全文

• 作者：Benjamin Mogesa ; Eranda Perera ; Hannah M. Rhoda ; John K. Gibson ; Jos Oomens ; Giel Berden ; Michael J. van Stipdonk ; Victor N. Nemykin ; Partha Basu
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：August 17, 2015
• 年：2015
• 卷：54
• 期：16
• 页码：7703-7716
• 全文大小：800K
• ISSN：1520-510X

文摘

The syntheses of cationic nickel complexes using N,N鈥?dimethyl piperazine 2,3-dithione (Me<sub>2sub>Dt<sup>0sup>) and N,N鈥?diisopropyl piperazine 2,3-dithione (<sup>isup>Pr<sub>2sub>Dt<sup>0sup>) ligands are reported. These ligands were used in synthesizing bis and tris(dithione)Ni(II) complexes as tetrafluoroborate or hexafluorophosphate salts, i.e., [Ni(<sup>isup>Pr<sub>2sub>Dt<sup>0sup>)<sub>2sub>][BF<sub>4sub>]<sub>2sub> ([1a][BF<sub>4sub>]<sub>2sub>), [Ni(<sup>isup>Pr<sub>2sub>Dt<sup>0sup>)<sub>2sub>][PF<sub>6sub>]<sub>2sub> ([1a][PF<sub>6sub>]<sub>2sub>), [Ni(Me<sub>2sub>Dt<sup>0sup>)<sub>2sub>][BF<sub>4sub>]<sub>2sub> ([1b][BF<sub>4sub>]<sub>2sub>), [Ni(<sup>isup>Pr<sub>2sub>Dt<sup>0sup>)<sub>3sub>][BF<sub>4sub>]<sub>2sub> ([2a][BF<sub>4sub>]<sub>2sub>), and [Ni(<sup>isup>Pr<sub>2sub>Dt<sup>0sup>)<sub>3sub>][PF<sub>6sub>]<sub>2sub> ([2a][PF<sub>6sub>]<sub>2sub>), respectively. Complex [2a][PF<sub>6sub>]<sub>2sub> was isolated from a methanolic solution of [1a][PF<sub>6sub>]<sub>2sub>. Compound [1a][BF<sub>4sub>]<sub>2sub> crystallizes in a trigonal crystal system (space group, P3<sub>1sub>/c) and exhibits unique packing features, whereas [2a][BF<sub>4sub>]<sub>2sub> crystallizes in a monoclinic (P2<sub>1sub>/n) space group. Cyclic voltammograms of [1a][BF<sub>4sub>]<sub>2sub> and [1b][BF<sub>4sub>]<sub>2sub> are indicative of four reduction processes associated with stepwise single-electron reduction of the ligands. Spectroelectrochemical experiments on [1a][BF<sub>4sub>]<sub>2sub> exhibit an intervalence charge transfer (IVCT) transition as a spectroscopic signature of the mixed-valence [Ni(<sup>isup>Pr<sub>2sub>Dt<sup>0sup>)(<sup>isup>Pr<sub>2sub>Dt<sup>1鈥?/sup>)]<sup>鈭?/sup> species. Analysis of this IVCT band suggests that this ligand based mixed valence complex, [Ni(<sup>isup>Pr<sub>2sub>Dt<sup>0sup>)(<sup>isup>Pr<sub>2sub>Dt<sup>1鈥?/sup>)]<sup>鈭?/sup>, behaves more like a traditional class II/III metal based mixed-valence complex. The density functional theory (DFT) and time dependent DFT calculations provide a theoretical framework for understanding the electronic structures and the nature of excited states of the target compounds that are consistent with their spectroscopic and redox properties. Vibrational spectra of [1a]<sup>2+sup> and [2a]<sup>2+sup> were investigated as discrete species in the gas phase using infrared multiple photon dissociation (IRMPD) spectroscopy.