Synthesis, Characterization, Photoluminescence, and Simulations of a CCC-NHC-Supported Pt₂Ag₂ Mixed-Metal Cluster Containing a PtAg₂ Metallacyclopropane

Abstract

The pincer CCC-bis(NHC)-supported Pt(II) complex 2, (1,3-bis(N-((trimethylsilyl)methyl)imidazol-2-ylidene)-2-phenylene)chloroplatinum(II), was prepared and was reacted with excess or stoichiometric silver(I) trifluoroacetate. The reaction with excess yielded the Pt 2 Ag 2 cluster 3, which to our knowledge contains the first unsymmetrically substituted example of a PtAg 2 metallacyclopropane, as revealed by X-ray crystallography. A distorted-octahedral configuration was also found in the coordination sphere of one of the silver atoms. Multiple weak hydrogen bonds (WHB) including C−H•••O, C−H•••F, and C−F•••π interactions were identified in the lattice of cluster 3. The unique structure of cluster 3 was simulated using density functional theory (DFT), which revealed that it was thermodynamically favored over the more expected configurations. The stoichiometric reaction with Ag(OCCF 3 ) afforded the simple ligand exchange product (1,3-bis(N-((trimethylsilyl)methyl)imidazol-2-ylidene)-2-phenylene)(trifluoroacetato)platinum(II) (4). The reaction of stoichiometric or excess AgOAc afforded only the monomeric product of simple ligand metathesis, (1,3-bis(N-((trimethylsilyl)methyl)imidazol-2ylidene)-2-phenylene)(acetato)platinum(II) ( 5). This observation is consistent with the hypothesis that the weak hydrogen bond network and the increased Lewis acidity of Ag(OCCF 3 ) are significant contributors to the structure of cluster 3. The photophysical properties of complexes 2−5 have been investigated. The emission color of the solution of cluster 3 was found to be concentration dependent.

Synthesis, characterization, photophysical properties, and catalytic activity of an SCS bis(N-heterocyclic thione) (SCS-NHT) Pd pincer complex

“…2 contains two 6,6-fused palladacycles in a twisted rac-conformation. [52][53][54] Furthermore, the rac-conformation of 3 has a chiral twist similar to the 5,6-fused-ring systems reported by Odinets 29 and to the 5,5-fused-ring complexes synthesized by Kruithof and coworkers. 43 While it is similar to the racconformation of the S-N-S ligand reported in 5-coordinate Cu complexes.…”

Self-assembly of a neutral platinum(ii) complex into highly emitting microcrystalline fibers through metallophilic interactions

“…The bi-exponential decay is due to the equilibrium between the emissive 3 MLCT/ 3 LC and a thermally populated non-radiative state. Hence, such emission can be attributed to the T 1 →S 0 radiative transition with mainly metal-perturbed 3 LC character, and the highest energy peak observed at 298 K (463 nm, 2.68 eV) agrees with the theoretical S 0 →T 1 (HOMO → LUMO) vertical excitation process computed at 432 (2.87 eV) nm in CHCl 3 .…”

“…The transition involved has been ascribed as 1 MMLCT. Excitation in this band, as well as in any other absorption leads to the yellow emission attributed to the corresponding 3 MMLCT. Furthermore, such solvophobic metallophilic interactions are accounted to play a major role into the nanoscale organization and molecular propagation for the self-assembly of the Pt-CF 3 tz-pyC 5 complex.…”

Phosphorescent Platinum(II) Complexes Featuring Chelated Acetoxime Pyrazoles: Synthetic, Structural, and Photophysical Study

“…Photophysics of Pt II compounds have been surveyed in reviews,, and it was a subject of several textbooks,, making clear that photophysical properties—reflected in such parameters as absorption and emission maxima, quantum yields, and emission lifetime—strongly depend on the nature of metal‐bound organic substrate and the degree of planarity of the luminescent complexes. The most efficient Pt II luminescent systems include [PtX 2 (diimine)] (where X is various anionic ligands), terpyridine, (porphyrin)Pt II[9] complexes, variety of compounds featuring C,C,C‐ , C,N,C‐ , N,C,N‐ , N,N,C‐pincers, and other platinum(II) species with cyclometalated ligands ,,. Current trend in studies of luminescent properties of platinum complexes includes weak intermolecular interaction effects on the photophysical properties (for review see ref, and for recent articles see refs).…”