Abstract
A series of cycloplatinated(II) complexes with general formula of [PtMe(Vpy)(PR3)], Vpy = 2-vinylpyridine and PR3 = PPh3 (1a); PPh2Me (1b); PPhMe2 (1c), were synthesized and characterized by means of spectroscopic methods. These cycloplatinated(II) complexes were luminescent at room temperature in the yellow–orange region’s structured bands. The PPhMe2 derivative was the strongest emissive among the complexes, and the complex with PPh3 was the weakest one. Similar to many luminescent cycloplatinated(II) complexes, the emission was mainly localized on the Vpy cyclometalated ligand as the main chromophoric moiety. The present cycloplatinated(II) complexes were oxidatively reacted with MeI to yield the corresponding cycloplatinated(IV) complexes. The kinetic studies of the reaction point out to an SN2 mechanism. The complex with PPhMe2 ligand exhibited the fastest oxidative addition reaction due to the most electron-rich Pt(II) center in its structure, whereas the PPh3 derivative showed the slowest one. Interestingly, for the PPhMe2 analog, the trans isomer was stable and could be isolated as both kinetic and thermodynamic product, while the other two underwent trans to cis isomerization.
Highlights
Luminescent cyclometalated platinum(II) complexes have been significantly studied by many researchers in the last decades [1,2,3,4,5,6,7,8,9,10,11]; publications in this field of research are increasing [12,13,14,15]
The electronic transitions of the cycloplatinated(II) complexes 1a-c were initially investigated by the UV-vis spectroscopy, and their spectra were characterized in detail by the help of density functional theory (DFT) and time dependence-DFT (TD–DFT) calculations
The nature of phosphine ligands affects the rate of oxidative addition reactions of cycloplatinated(II) complexes with MeI
Summary
Luminescent cyclometalated platinum(II) complexes have been significantly studied by many researchers in the last decades [1,2,3,4,5,6,7,8,9,10,11]; publications in this field of research are increasing [12,13,14,15]. In a comparison between PPh2Me and PPh3 ligands, the rate constants attributed to the PPh2Me derivative are 3-5-fold more than those for PPh3, indicating the electronic and steric differences [63] In this manner, it is expected that the PPhMe2 derivative reactions should be considerably faster than those of PPh2Me. In the framework of our experiences on the photophysical [30,31,64,65,66,67,68,69] and the kinetico-mechanistic studies [70,71,72,73,74] of cyclometalated platinum complexes, some cycloplatinated(II or IV) complexes with 2-vinylpyridine (Vpy) and phosphine ligands (PPh3 [75], PPh2Me [76] and PPhMe2) were designed. Density functional theory (DFT) calculations were performed for both investigations and support the experimental data
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
