Luminescent Anionic Cyclometalated Organoplatinum (II) Complexes with Terminal and Bridging Cyanide Ligand: Structural and Photophysical Properties

Abstract

We present the synthesis and characterization of two series of mononuclear heteroleptic anionic cycloplatinated­(II) complexes featuring terminal cyanide ligand Q+[Pt­(C^N)­(p-MeC6H4)­(CN)]− [C^N = benzoquinolate (bzq), Q+ = K+ 1 and NBu4 + 4; 2-phenylpyridinate (ppy), Q+ = K+ 2 and NBu4 + 5 and 2-(2,4- difluorophenyl)­pyridinate (dfppy), Q+ = K+ 3 and NBu4 + 6] and a series of symmetrical binuclear complexes (NBu4)­[Pt2(C^N)2(p-MeC6H4)2(μ-CN)] (C^N = bzq 7, ppy 8, dfppy 9). Compounds 5, 6, and 7–9 were further determined by single-crystal X-ray diffraction. There are no apparent intermolecular Pt···Pt interactions owing to the presence of bulky NBu4 + counterion. Slow crystallization of K­[Pt­(ppy)­(p-MeC6H4)­(CN)] 2 in acetone/hexane evolves with formation of yellow crystals, which were identified by single-crystal X-ray diffraction methods as the salt complex {[Pt­(ppy)­(p-MeC6H4)­(CN)]2K3(OCMe2)4(μ-OCMe2)2}­[Pt­(ppy)­(p-MeC6H4)­(μ-CN)­Pt­(ppy)­(p-MeC6H4)]·2acetone (10), featuring the binuclear anionic unit 8– neutralized by an hybrid inorganic–organometallic coordination polymer {[Pt­(ppy)­(p-MeC6H4)­(CN)]2K3(OCMe2)4(μ-OCMe2)2}+. The photophysical properties of all compounds were recorded in powder, polystyrene film, and solution states with a quantum yield up to 21% for 9 in the solid state. All complexes displayed bright emission in rigid media, and for the interpretation of their absorption and emission properties, density functional theory (DFT) and time-dependent DFT calculations were applied.

Cyanido-bridged diplatinum(ii) complexes: ligand and solvent effect on aggregation and luminescence

“…Recently, a conceptually similar series of complexes with diplatinum cyanido-bridged anions [NBu 4 ][{Pt(C^N)( p -MeC 6 H 4 )}(μ-CN)] have been reported, which bear bidentate C^N cyclometalated motifs. 28 The Pt centers are found in distorted square-planar environments, the structural parameters around the metal ions (Table S2, ESI†) are similar to those of the neutral monomeric congeners [Pt(C^N^ / *N)(CN)], 24 and of related complexes bearing C^N^ / *N ligands. 3 c ,25,30 c ,32…”

“…The structures of complexes 1, 3$CH 2 Cl 2 and 4 were determined by single crystal X-ray diffractometry, crystal data and renement details are listed in Table S1 (ESI), † views of molecular ions and fragments of crystal packing are depicted in [{Pt(C^N)(p-MeC 6 H 4 )}(m-CN)] have been reported, which bear bidentate C^N cyclometalated motifs. 28 The Pt centers are found in distorted square-planar environments, the structural parameters around the metal ions (Table S2, ESI †) are similar to those of the neutral monomeric congeners [Pt(C^N^/*N)(CN)], 24 and of related complexes bearing C^N^/*N ligands. 3c, 25,30c,32 Complexes 1 and 2 reveal both crystallographic and chemical disorder in the packing of the cations.…”

Luminescent Heterobimetallic PtII–AuI Complexes Bearing N-Heterocyclic Carbenes (NHCs) as Potent Anticancer Agents

“…The calculated spin densities over Pt in 1 – 3 are 7.3%, 6.25%, and 6.4%, respectively (Figures S66–S69). Hence, 3 MLCT characters are expected to follow the 1 > 3 > 2 trend …”

“…Hence, 3 MLCT characters are expected to follow the 1 > 3 > 2 trend. 50 Cytotoxic Activity Evaluation. Before conducting in vitro experiments, the stability of all complexes was determined using spectroscopic techniques such as NMR (DMSO-d 6 ) and UV−vis (DMSO and H 2 O).…”

Ladder-like heteropolynuclear assemblies via cyanido bridges and platinum(ii)–thallium(i) bonds: structural and photophysical properties

“…These values compare well with those recently reported for K[Pt( ppy)( p-MeC 6 H 4 ) ( 13 CN)] (δ 157.4, 1 J Pt-C = 882 Hz). 14 With the aim of investigating the metallophilic affinity of the anionic platinum substrates toward Tl(I), we decided to examine the reactivity of the synthons "[Pt(C^N)(C 6 F 5 )(CN)] − " toward TlPF 6 . Thus, the heteropolynuclear complexes, 3 and 4 were synthesized via a two-step modular synthesis (Scheme 1ii, iii).…”