Binuclear complexes of Pt(II) with platinated 2-phenylbenzothiazole and bridged derivatives of pyridin- and benzothiazol-2-thiols

Binuclear complexes of Pt(II) cycloplatinated with 2-phenylbenzothiazole and bridging ligands have been shown to contain the Pt-Pt bond. The complexes have been studied by X-ray diffraction, ¹H NMR and electronic absorption spectroscopy, and electrochemical methods. The complexes cis-N_(bt),S-isomers with antisymmetric positions of the cyclometalated and the bridging ligands have been detected in the crystals as well as in the solutions. The low-wavelength absorption and luminescence of the complexes have been assigned to the metal-metal-ligand charge transfer. The two-electron oxidation and reduction waves in the voltamperograms are associated with the metal- and the ligand-centered processes, respectively.     

Optical and spectroscopic properties of substituted oxa- and thiazole luminophores metalated with platinum metals

The cyclometalated [M(pbo)En]PF₆(M = Pd(II), Pt(II)), [M(pbo)₂En]PF₆ (M = Rh(III), Ir(III)), and [Rh(C∧N)₂En]PF₆ ((C∧N)^? are the deprotonated forms of 2-phenylbenzoxazole (pbo), 2,5-diphenyloxazole (dpo), 2-phenylbenzothiazole (pbt), 2-biphenyl-4-yl-5-phenyloxazole (bpo), and 2-biphenyl-4-yl-6-phenylbenzoxazole (bpbo) and En is ethylenediamine) complexes are studied by ¹H NMR spectroscopy, IR spectroscopy, and electronic absorption and emission spectroscopy. Metalation of luminophores leads to the formation of five-membered {M(C∧N)} cycles in the composition of plane-square and octahedral complexes of the cis-C,C structure. In addition to the intraligand (IL) π-π* optical transitions in the UV region, the complexes are characterized by long-wavelength metal-to-ligand charge-transfer (MLCT) absorption bands in the region of 366–416 nm. The phosphorescence of the complexes in the visible region (482–531 nm) is attributed to radiative transition from the mixed IL/MLCT electronically excited state. The temperature quenching of the phosphorescence of complexes is attributed to the thermally activated population of metal-centered electronically excited states with subsequent nonradiative deactivation.     

The Effect of Hg(II) on the Optical Characteristics of Cycloiridated 2-Phenylbenzothiazole Complexes with Chelating Ligands Containing Sulfur Donor Atoms

The [Ir(bt)₂(S^S)], [Ir(bt)₂(S^N)], and [Ir(bt)₂(CH₃CN)₂]PF₆ complexes, where (bt)^? is a deprotonated form of 2-phenylbenzothiazole and (S^S)^? and (S^N)^? are diethyldithiocarbamate, O-ethyldithiocarbonate, 2-mercaptobenzothiazolate, 2-mercaptobenzoxazolate, and 2-mercaptopyridinate ions, and the effect of Hg(II), Cu(II), Cd(II), and Zn(II) cations on the optical characteristics of these complexes are studied by electron absorption spectroscopy and emission spectroscopy. A hypsochromic shift of the absorption and phosphorescence bands of complexes in substituting the (S^S)^? and (S^N)^? chelating ligands with acetonitrile ligands is attributed to a lower energy of d_Ir orbitals compared with the mixed d_Ir/p(S) orbitals. It is shown that the presence of Hg(II) cations results in a hypsochromic shift of the absorption and phosphorescence bands of complexes [Ir(bt)₂(S^S)] and [Ir(bt)₂(S^N)] because of an effective reaction of substitution of chelating ligands to acetonitrile ligands.     

Optical and electrochemical characteristics of ethylenediamine complexes of Pt(II) and Ir(III) with metalated 2-phenyl- and 2-naphthylbenzothiazole

The cyclometalated complexes [Pt(С^N)En]PF₆ and [Ir(C^N)₂En]PF₆ ((C^N)^– are deprotonated forms of 2-phenylbenzothiazole or 2-naphthylbenzothiazole and En is ethylenediamine) are studied by ¹Н NMR, IR, electronic absorption, and emission spectroscopy, as well as by voltammetry. Metalation of heterocyclic ligands leads to the formation of five-membered {M(C^N)} cycles in the composition of squareplanar Pt(II) complexes and octahedral Ir(III) complexes of the cis-С,С structure. A bathochromic shift of the metal-to-cyclometalated ligand charge transfer bands and a decrease in the potential difference between the single-electron waves of metal-centered oxidation and ligand-centered reduction of complexes upon substitution of 2-phenylbenzothiazole by 2-naphthylbenzothiazole and of Pt(II) by Ir(II) are shown. The phosphorescence of complexes in the visible region is assigned to the radiative transition from the metal-modified intraligand electronic excited state.     

Supramolecular Assembly of Metal Complexes by (Aryl)I⋅⋅⋅d [PtII] Halogen Bonds

The theoretical data for the half-lantern complexes [{Pt( )(μ- )}₂] [ 1 – 3 ; is cyclometalated 2-Ph-benzothiazole; is 2-SH-pyridine ( 1 ), 2-SH-benzoxazole ( 2 ), 2-SH-tetrafluorobenzothiazole ( 3 )] indicate that the Pt ⋅⋅⋅ Pt orbital interaction increases the nucleophilicity of the outer d orbitals to provide assembly with electrophilic species. Complexes 1 – 3 were co-crystallized with bifunctional halogen bonding (XB) donors to give adducts ( 1 – 3 )₂ ⋅ (1,4-diiodotetrafluorobenzene) and infinite polymeric [ 1⋅ 1,1′-diiodoperfluorodiphenyl]_n. X-ray crystallography revealed that the supramolecular assembly is achieved through (Aryl)I ⋅⋅⋅ d [Pt^II] XBs between iodine σ-holes and lone pairs of the positively charged (Pt^II)₂ centers acting as nucleophilic sites. The polymer includes a curved linear chain ⋅⋅⋅ Pt₂ ⋅⋅⋅ I(arene^F)I ⋅⋅⋅ Pt₂ ⋅⋅⋅ involving XB between iodine atoms of the perfluoroarene linkers and (Pt^II)₂ moieties. The ¹⁹⁵Pt NMR, UV/Vis, and CV studies indicate that XB is preserved in CH(D)₂Cl₂ solutions.     

Structures and optical and electrochemical properties of the Pt(II) and Pd(II) complexes with cyclometallated 2-phenylbenzothiazole and 1,4,7-trithiocyclononane

The distorted square pyramidal structures of the Pt(II) and Pd(II) complexes with cyclometallated 2-phenylbenzothiazole and flexible 1,4,7-trithiocyclononane are shown by X-ray diffraction analysis, IR spectroscopy, and ¹Н, ¹³С{¹H{, and ¹⁹⁵Pt NMR spectroscopy. The axial interaction of the d _Z2 orbital of Pt(II) and Pd(II) with the S atom of 1,4,7-trithiocyclononane results in the temperature quenching of the intraligand phosphorescence of the cyclometallated complexes in a solution and the one-electron ligand- and metal-centered reduction and oxidation of the complexes with the formation of the relatively stable Pd(III) complex (CIF file CCDC no. 1483011).