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

Abstract

Pt(dbbpy)(bdt) and Pt(tmphen)(bdt) (dbbpy = 4,4'-di-t-butyl-2,2'-bipyridine; tmphen = 3,4,7,8tetramethyl-1,10-phenanthroline; bdt 2-= 1,2-benzenedithiolate) are reported. Pt(dbbpy)(bdt) reacts with one equivalent of methyl iodide to give the S-methylated product, [Pt(dbbpy)(CH 3 bdt)]I. The reaction follows second order kinetics with a rate constant of 1.3×10-2 M-1 s-1 at 311 K. The accumulated data are consistent with direct nucleophilic attack by the coordinated bdt 2ligand sulfur atom on the carbon atom of the methyl iodide. Variabletemperature experiments yield an Arrhenius activation energy of 51 ± 3 kJ/mol. Activated complex reaction theory yields an enthalpy and entropy of activation of 48 ± 2 kJ/mol and-125 ± 7 J/(mol K), respectively, consistent with an S N 2 reaction mechanism. The structure of the monosulfinate adduct, Pt(dbbpy)(bdtO 2), also is reported. The fluid-solution luminescence of Pt(tmphen)(bdt) is concentration dependent and characterized by a 1591  41 ns lifetime and 2.6 ± 0.2% quantum yield at infinite dilution. The observed chemical reactivity and self-quenching behavior have important implications for the design of photochemical devices based on the platinum(II) diimine dithiolate chromophore.

Synthesis and Reactivity of Cp*IrIII Complexes with a C–S Chelate Displaying Metal/Sulfur Bifunctionality

“…Electrophilic alkylation of thiolato ligands bound to transition metals has received much interest as a generic model for various metalloenzymes. ,, The reactivities and mechanistic aspects have been extensively studied to define the roles of metal–sulfur bonds. In analogy to the C–N chelating amidoiridium complexes with enhanced basic properties, , the σ-donating C–S chelate will facilitate alkyl transfer onto the nucleophilic sulfur site.…”

(2,2′-Bipyridine)(1,2-dicyanoethene-1,2-dithiolato)platinum(II)

“…Since Eisenberg's initial report on luminescent platinum(II) diimine dithiolate complexes (Zuleta, et al 1989), this class of compounds has been utilized in areas such as dyesensitized solar cells (Islam et al, 2001;Geary et al, 2005), photosplitting of water (Zhang et al, 2007, Zarkadoulas et al, 2012 and non-linear optics (Cummings et al, 1997). X-ray structures of platinum(II)dithiolate complexes with modified bipyridine ligands are common in papers such as those describing the photophysical properties (Lazarides et al, 2011), reaction kinetics (Stace et al, 2016), or charge-transfer properties (Smucker et al, 2003;Browning et al, 2014) of these compounds. The crystal structure of one of the initial complexes, Pt(2,2 0 -bpy)(mnt), which inspired many variations, has heretofore not been published.…”

Crystal structure of bis(acetonitrile-κN)(4,4′-di-tert-butyl-2,2′-bipyridine-κ2 N,N′)platinum(II) bis(tetrafluoridoborate) packing as head-to-head dimers

“…The solubility and apt geometry of the (dbbpy)platinum(II) complex make it a desirable building block for coordination-driven self-assembly of homo-metallic (Zhang, et al, 2017) and hetero-metallic (Bera et al, 2001) supramolecular complexes. This platinum(II) diimine can also be combined with dithiolene ligands to study methylation kinetics (Stace, et al, 2016), generate charge-transfer materials (Smucker, et al, 2003), or make model complexes for examining photophysical properties (Lazarides, et al, 2011;Yang et al, 2014).…”