Intramolecular Metal···Sulfur Interactions of Platinum(II) 1,4,7-Trithiacyclononane Complexes with Bipyridyl Ligands:  The Relationship between Molecular and Electronic Structures

Abstract

Five platinum(II) 1,4,7-trithiacyclononane (ttcn) complexes with bidentate-substituted 2,2'-bipyridine ligands have been prepared and structurally characterized: [Pt(bpy)(ttcn)](PF6)2 (bpy = 2,2'-bipyridine), triclinic, P1, a = 10.2529(3) A, b = 10.7791(3) A, c = 10.7867(3) A, alpha = 83.886(1) degrees, beta = 87.565(1) degrees, gamma = 84.901(1), V = 1179.99(6) A3, Z = 2; [Pt(4,4'-dmbpy)(ttcn)](PF6)2 x CH3CN x H2O (4,4'-dmbpy = 4,4'-dimethyl-2,2'-bipyridine), triclinic, P1, a = 10.1895(3) A, b = 11.8566(4) A, c = 13.1004(4) A, alpha = 77.345(1) degrees, beta = 79.967(1) degrees, gamma = 72.341(1) degrees, V = 1461.56(8) A3, Z = 2; [Pt(5,5'-dmbpy)(ttcn)](PF6)2 (5,5'-dmbpy = 5,5'-dimethyl-2,2'-bipyridine), triclinic, P1, a = 10.6397(4) A, b = 10.8449(4) A, c = 11.2621(4) A, alpha = 90.035(1) degrees, beta = 98.061(1) degrees, gamma = 91.283(1) degrees, V = 1286.32(8) A3, Z = 2; [Pt(dbbpy)(ttcn)](PF6)2 x CH3NO2 (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine), triclinic, P1, a = 11.5422(7) A, b = 11.6100(7) A, c = 13.6052(9) A, alpha = 85.902(1) degrees, beta = 89.675(1) degrees, gamma = 74.942(1) degrees, V = 1755.90(19) A3, Z = 2; and [Pt(dtfmbpy)(ttcn)](PF6)2 x CH3CN (dtfmbpy = 5,5'-di-trifluoromethyl-2,2'-bipyridine): monoclinic, P2(1)/c, a = 13.1187(9) A, b = 20.9031(15) A, c = 11.3815(8) A, beta = 105.789(2) degrees, V = 3003.3(4) A3, Z = 4. For each salt, the platinum(II) center of the cation is bonded to two nitrogen atoms of the chelating diimine and two sulfur atoms of the thioether macrocycle. The third sulfur atom of ttcn forms a long apical interaction with the metal center (2.84-2.97 A), resulting in a flattened square pyramid structure. An examination of these and 17 other structures of platinum(II) ttcn complexes reveals a correlation between the apical Pt...S distance and the donor properties of the ancillary ligands, suggesting a means for using variations in ligand electronic properties to tune molecular structure. The room-temperature absorption spectra in acetonitrile solution show a broad and comparatively low-energy MLCT band maximizing near approximately 390 nm for the bpy and dialkyl-substituted bipyridyl derivatives. The maximum is dramatically red-shifted to 460 nm in the spectrum of the dtfmbpy complex as a result of the electron-withdrawing properties of the -CF(3) groups. The 3:1 EtOH/MeOH 77 K glassy solution emission spectra exhibit low-energy emission bands (lambdamax, 570-645 nm), tentatively assigned as originating from a lowest, predominantly spin-forbidden MLCT excited state that is stabilized by apical Pt...S interactions.

Synthesis, characterization and electrophosphorescent properties of mononuclear platinum(II) complexes based on 2-phenylbenzoimidazole derivatives

“…Recently, square planar platinum(II) complexes have attracted intensive interest for their potential application in different fields such as chemical sensors [1,2], photovoltaic devices [3,4], emissive probes for DNA [5], and especially organic light-emitting diodes (OLEDs) [6][7][8][9][10][11]. Since the first report of the phosphorescent platinum(II) complex (PtOEP) in 1998 [12], a breakthrough using platinum(II) complex as efficient electroluminescent materials has been demonstrated, and a series of platinum(II) complexes, based on N^N [13,14], C^N [15][16][17][18][19][20], N^O [21], N^N^N [22,23], C^N^N [24][25][26][27][28][29][30][31], O^N^N [32] aromatic chelating ligands, have been synthesized one after the other.…”

Kinetics of the methylation of a platinum(II) diimine dithiolate complex

“…All reagents were obtained from Aldrich, Pressure Chemical, or Acros. Pt(dbbpy)Cl 2 was prepared from K 2 PtCl 4 as previously described [44] and washed with copious amounts of water to remove trace HCl. Deuterated solvents for NMR spectroscopy were obtained from Cambridge Isotope Laboratories.…”

X-ray and synchrotron diffraction studies of 2-(pyridin-2-yl)-1,10-phenanthroline in the role of ligand for two copper polymorphs or hydrogen bonded with 2,2,6,6-tetramethyl-4-oxopiperidinium hexafluorophosphate

“…Our ongoing research efforts primarily focus on utilizing biand tridentate chelating imine-based ligands: (i) to tune the electronic nature of square-planar d 8 -electron and octahedral d 6 -electron late transition metals for promising multi-redox catalytic applications and to explore their photophysical properties (see, for example, Pt complexes: Chatterjee et al, 2012;Chatterjee, Krause, Oliver et al, 2010;Green et al, 2005;Grove et al, 2008;Jude, Carroll & Connick, 2003;Jude, Krause Bauer & Connick, 2003;Pd complexes: Tastan et al, 2006); (ii) to bridge multiple metal centres to form more elaborate molecular architectures (Jude et al, 2005;Willison et al, 2008); and (iii) to continue our studies utilizing coinage metals (Collins et al, 2007). Our most recent focus has been the tridentate ligand 2-(pyridin-2-yl)-1,10-phenanthroline (php).…”