Phosphorescent heterobimetallic complexes involving platinum(iv) and rhenium(vii) centers connected by an unsupported μ-oxido bridge

Abstract

Heterobimetallic compounds [(C^N)LMePt(μ-O)ReO] (C^N = ppy, L = PPh, 2a; C^N = ppy, L = PMePh, 2b; C^N = bhq, L = PPh, 2c; C^N = bhq, L = PMePh, 2d) containing a discrete unsupported Pt(iv)-O-Re(vii) bridge have been synthesized through a targeted synthesis route. The compounds have been prepared by a single-pot synthesis in which the Pt(iv) precursor [PtMeI(C^N)L] complexes are allowed to react easily with AgReO in which the iodide ligand of the starting Pt(iv) complex is replaced by an ReO anion. In these Pt-O-Re complexes, the Pt(iv) centers have an octahedral geometry, completed by a cyclometalated bidentate ligand (C^N), two methyl groups and a phosphine ligand, while the Re(vii) centers have a tetrahedral geometry. Elemental analysis, single crystal X-ray diffraction analysis and multinuclear NMR spectroscopy are used to establish their identities. The new complexes exhibit phosphorescence emission in the solid and solution states at 298 and 77 K, which is an uncommon property of platinum complexes with an oxidation state of +4. According to DFT calculations, we found that this emission behavior in the new complexes originates from ligand centered LC (C^N) character with a slight amount of metal to ligand charge transfer (MLCT). The solid-state emission data of the corresponding cycloplatinated(iv) precursor complexes [PtMeI(C^N)L], 1a-1d, pointed out that the replacement of I by an ReO anion helps enhancing the emission efficiency besides shifting the emission wavelengths.

Synthesis, structural characterization, and luminescence properties of mono- and di-nuclear platinum(II) complexes containing 2-(2-pyridyl)-benzimidazole

“…method. Calculated emission wavelengths (the difference between ground state and excited state) [21] are 503, 512, 557, 515 nm (gas phase) for the complexes 1-4 respectively, which are almost close to the experimental values achieved for themrecorded (540, 537, 540, 530 nm for complexes 1, 2, 3 and 4, respectively, in solid).…”

“…Among different classes of transition metal complexesThese include, phosphorescent organotransition metal compounds have been widely investigated asthat can serve as efficient emitters in optoelectronic devices [6,7] and molecular sensors [8][9][10] owing to their high luminescence quantum yields [11][12][13][14][15][16]. Of particular interest are Pt(II) complexes of strong field ligands like benzo[h]quinolinate (bhq) and 2phenylpyridinate (ppy -) [17][18][19][20][21][22][23]. Additionally, cycloplatinated(II) complexes bearing the rollover 2,2′-bipyridinate (bpy) ligand can also be emissive in solution or solid state [24][25][26].…”

Design of Luminescent, Heteroleptic, Cyclometalated PtII and PtIV Complexes: Photophysics and Effects of the Cyclometalated Ligands

“…Accordingly, the Pt−N1 bond lengths trans to C 6 F 5 [2.092(7)–2.121(3) Å] is shorter than the Pt−N2 trans to the metalated C bzq [2.130(2)–2.264(3) Å]. The bite angles (C‐Pt‐N) in the bzq [81.2(2)–81.7(2)°] and in the second cyclometalated ligand [79.5(3)–80.8(3)°] compare well to those reported for other cyclometalated Pt IV compounds . Inspection of the molecular packing (Figures S8–S11) revealed the presence of weak intermolecular interactions that give rise to extended chains ( 2 b , 2 e ) or dimers ( 2 d ) by π⋅⋅⋅π contacts between the cyclometalated rings (bzq⋅⋅⋅dfpy 2 b , Br‐pbt⋅⋅⋅Br‐pbt 2 d , bzq⋅⋅⋅bzq 2 e ).…”

Luminescent mononuclear and dinuclear cycloplatinated (II) complexes comprising azide and phosphine ancillary ligands

“…This complex exhibited interesting luminescence properties at 298 K with a dual emission band originating from the cyclometalated ligand (intramolecular) and aggregations (intermolecular). Using this observation and our previous experiences in the field of luminescent cycloplatinated (II) complexes, we decided to design a series of cycloplatinated (II) complexes involving N 3 − and phosphine (mono and diphosphines) ancillary ligands and deprotonated 7,8‐benzo[ h ]quinoline as a C^N chelate. The products were identified by nuclear magnetic resonance (NMR) spectroscopy ( 1 H and 31 P) and in one case by X‐ray crystallography.…”