Cis and trans-bis(tetrathiafulvalene-acetylide) platinum(ii) complexes: syntheses, crystal structures, and influence of the ancillary ligands on their electronic properties

Abstract

A series of four platinum(II) complexes bearing two tetrathiafulvalene acetylide ligands coordinated either cis or trans to the metal center are reported: cis-Pt(bipy)(C≡CMe(3)TTF)(2), cis-Pt(tBu(2)bipy)(C≡CMe(3)TTF)(2), cis-Pt(dppe)(C≡CMe(3)TTF)(2) and trans-Pt(PPh(3))(2)(C≡CMe(3)TTF)(2). The X-ray diffraction studies of the four complexes are reported and discussed. The electrochemical investigations carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) evidenced different redox behavior as a function of the ancillary ligand. Only for the cis-Pt(dppe)(C≡CMe(3)TTF)(2) complex is the first oxidation wave resolved (ΔE = 70 mV) into two one-electron processes. Spectroelectrochemical investigations performed on the four complexes did not evidence any electronic interactions between the two organic electrophores. The splitting of the first oxidation wave observed in cis-Pt(dppe)(C≡CMe(3)TTF)(2) is mainly explained by the non-equivalence of the two TTF moieties induced by the geometrical constraint imposed by the ancillary dppe ligand as found by density functional theory calculations.

Metal (Hg, Pt, Ru) Bisalkynyl Bridge between Tetrathiafulvalene Electrophores and Electronic Interplay

“…In both cases, upon gradual oxidation, only the spectral signature of the TTF radical cation species at 460 nm and 680 nm is observed for 5 and at 440 nm and 810 nm for 7 with no evidence of intervalence charge-transfer (IVCT) bands at lower energies. Similar evolution of the UV-Vis-NIR spectra were observed for the Pt complex with a shorter linkage, trans-[Pt(C≡CMe 3 TTF) 2 (PPh 3 ) 2 ] [23].…”

“…Moreover, within this complex, the TTF and the ruthenium center are also strongly electronically coupled [17,18]. Other trans bis(acetylide) metallic linkers have also been reported in the literature (M = Cr [19][20][21][22], Pt [23]) but these organometallic linkers do not allow an electrochemically measurable electronic interaction between the TTFs. However, the absence of electrochemical evidence for the formation of mixed valence species in the case of the Cr bis(acetylide) linker did not impede on the formation of a mixed valence species in the solid state.…”

Fragmentation pathways analysis for the gas phase dissociation of protonated carnosine-oxaliplatin complexes

“…[48] The use of the B3LYP/LANL2DZ computational protocol in investigating transition metal containing compounds is well established. [49][50][51][52][53][54][55][56][57][58][59][60][61] In fact, it was recently used to successfully investigate the structures of the anti-arthritic drug auranofin and its complexes with cysteine; [45] to model CO adsorption on Pt nanoclusters; [62] to obtain structural information and binding energies for the complexation of cis-and trans-Pt(NH 3 ) 2 Cl + to guanine; [57] to investigate monomeric complexes between cisplatin and glutathione; [63] to obtain excellent agreement with X-ray data for cisplatin analogues [64] and oxaliplatin analogues [65] ; as well as to examine the mechanism of Pt and Pd catalysed coupling and cyclopropanation reactions between olefins. [66] Most recently, this level of theory was used to study the interactions of the anticancer Pt containing drug oxaliplatin with each of the cytoplasmic thiol containing tripeptide ligands γ-L-glutamyl-L-cysteinyl-glycine (GSH) [67] as well as the biologically active βalanine-L-histidine dipeptide carnosine.…”

Electron transfer dynamics and excited state branching in a charge-transfer platinum(ii) donor–bridge-acceptor assembly

“…2,[4][5][6][7][8][9][10] There is currently much interest in understanding the behaviour and energy relaxation processes that occur immediately after light absorption. Transition metal donor-bridge-acceptor (DBA) molecular triads and their multi-donor/acceptor relatives have proven to be an effective design motif in which a photoinduced CSS can be attained.…”

“…Transition metal donor-bridge-acceptor (DBA) molecular triads and their multi-donor/acceptor relatives have proven to be an effective design motif in which a photoinduced CSS can be attained. 2,[4][5][6][7][8][9][10] There is currently much interest in understanding the behaviour and energy relaxation processes that occur immediately after light absorption. Electron transfer from a nonthermalised manifold, which competes with vibrational relaxation in the excited state, is one such process.…”