1352575-59-7Relevant academic research and scientific papers
Heteropolynuclear Pt(II)-M(I) clusters with a C^N^C biscyclometalated ligand
Fuertes, Sara,Woodall, Christopher H.,Raithby, Paul R.,Sicilia, Violeta
, p. 4228 - 4240 (2012/08/08)
The mononuclear complex [(EtO2C-C^N ^C)Pt(dmpyz)] (1) (dmpyz = 2,5-dimethylpyrazine) has been synthesized by reaction of [(EtO2C-C^N^C)Pt(dmso)] (A) with dmpyz in a 1:1 molar ratio in dichloromethane. Complex 1 is the precursor for preparing the homodinuclear complex [{(EtO2C-C^N ^C)Pt}2(μ-dmpyz)] (2) and the heterotrinuclear clusters [{(EtO2C-C^N^C)Pt(dmpyz)}2M]X (M = Cu, X = PF6 (3); M = Ag, X = BF4 (4)). Compounds 1, 2, and 4 were studied by X-ray diffraction methods. In the crystal packing of 1 and 2, the molecules display short intermolecular π???π contacts, which control the solid-state emissive behavior. X-ray study on 4 shows two [Pt2Ag] sandwich-type clusters in the asymmetric unit, both with the two square-planar (R-CNC)Pt(dmpyz) moieties stabilized by two Pt → Ag donor-acceptor bonds as well as by η1- and η2-Ag-C interactions. Intramolecular π-π contacts were found between the pyridine rings of the CNC ligands within the same Pt 2Ag cluster. 1H and 195Pt NMR studies confirm that the Pt2M cluster is also retained in solution at room temperature. 195Pt NMR spectra of 3 and 4 show signals shifted significantly downfield when comparing with that for the monomer (1), which is attributed to the presence of Pt-M dative bonds. At lower temperatures (T = 193 K), the copper derivative definitely falls apart, whereas the silver one still holds up unbroken. In the solid state at 77 K, compounds 1-4 give red emissions arising from 3ππ excited states due to the intra- or intermolecular π-π contacts observed in the crystal structures. As expected, in glassy solutions (77 K), compound 3 displays analogous emissions to those from the starting material (1). Complexes 1 and 2 show structured emission bands that are particularly sensitive to the λex (HE and LE). In contrast, 4 displays an unstructured emission at 680 nm with a shoulder at 556 nm; both are not dependent on the λex. DFT and TDDFT computational studies have been performed on 1 and 2, which support the conclusions drawn from the photophysical studies.
New C∧N∧C bis-cyclometalated platinum(II) complexes: Synthesis, structures, and photophysical properties
Fuertes, Sara,Brayshaw, Simon K.,Raithby, Paul R.,Schiffers, Stephanie,Warren, Mark R.
, p. 105 - 119 (2012/04/23)
The reaction of a new ligand, ethyl 2,6-diphenylisonicotinate (EtO 2C-C∧N∧C-H2), with K2PtCl4 in acetic acid affords the monocyclometalated complex [{(EtO2C- C∧N∧C-H)-Pt(μ-Cl)}2] (1), which transforms to the bis-cyclometalated derivative [Pt(EtO2C-C∧N∧C)(DMSO)] (2) when heated in hot DMSO. Complex 2 is the precursor for preparing a new series of neutral mononuclear bis-cyclometalated complexes [Pt(EtO2C- C∧N∧C)(L)] (L = tht (3), PPh3 (4), CN-tBu (5), py (6), py-tBu (7), py-NH2 (8), py-CN (9), py-CONH 2 (10)). These new complexes have been characterized spectroscopically, and structures of 2-10 have been determined crystallographically. Within each crystal structure the individual molecules pack in a head-to-tail arrangement. Noncovalent interactions, including ππ, C-HO, C-HN, N-HPt, N-Hπ, C-Hπ, and N-HO, contribute significantly to the supramolecular structures displayed by these complexes in the solid state. All complexes display UV-vis absorptions in dichloromethane solution. Excitation and emission studies as well as lifetime measurements are described and can be correlated to the solid-state structures of the complexes. DFT and TDDFT computational studies have been performed on 5 and 8 which support the conclusions drawn from the photophysical studies.
