An Outer-Sphere Two-Electron Platinum Reagent

Abstract

A strategy for designing cooperative outer-sphere two-electron platinum reagents is demonstrated. The novel platinum(II) complex, [Pt(tpy)(pip2NCN)][BF4] (1(BF4-)) (tpy = 2,2':6',2' '-terpyridine, pip2NCN- = 2,6-(CH2N(CH2)5)2-C6H3-), in which the metal is bonded to two pincer type ligands, has been prepared. Treatment of 1 with protic acid results in protonation of the pendant piperdyl groups, allowing for the isolation of [Pt(tpy)(pip2NCNH2)][PF6]3 (2(PF6-)3). 1H NMR spectra of 1 and 2 establish that in each complex the terpyridyl ligand is tridentate, whereas the piperdyl ligand is monodentate, bonded to platinum through the phenyl ring. The structure of the protonated complex was confirmed by an X-ray crystallographic study of crystals of 2(Cl-)3.4H2O. The cyclic voltammagram of 1 exhibits two reversible one-electron reduction waves at E degrees ' = -0.98 V and E degrees ' = -1.50 V (E degrees ' = (Epc + Epa)/2), with a DeltaEp of 65 and 61 mV, respectively. In contrast to other Pt(II) complexes, including 2, this complex also undergoes a nearly reversible two-electron oxidation process at E degrees ' = 0.40 V (DeltaEp = 43 mV, 0.01 V/s). The accumulated data are consistent with the unusual ligand architecture of 1 being capable of stabilizing and allowing for facile interconversion between the Pt(II) and Pt(IV) oxidation states.

Linear homobimetallic 4-thioacetyl-substituted NCN pincer palladium(II) and platinum(II) complexes with N-bidentate connecting units (NCN=[C6H2(CH2NMe2)2-2,6-R-4]−)

“…Previously, a similar behavior has been noted for related palladium compounds [34]. This shows that these complexes are insulators rather than conductors [40], which is consistent with the similar electron-donating ability for neutral donor ligands with Fig. 1.…”

“…[Pt(pip 2 NCN) (2,2 0 :6 0 ,2 00 -terpyridine)] + [40]. The irreversible reduction peak at E p,red = À0.73 V is characteristic for thio-acetyl NCN pincer ligands and only occurs from an oxidized form of this unit (vide supra) [27,36].…”

Incorporating ECE-pincer metal complexes as functional building blocks in semisynthetic metalloenzymes, supramolecular polypeptide hybrids, tamoxifen derivatives, biomarkers and sensors

“…The groups of Weck and coworker [57] and Reinhoudt and coworkers [58] elegantly used the well-established properties of cationic ECE-pincer metal(II) complexes coordinating to (substituted) pyridines [59][60][61][62][63][64][65][66][67][68][69][70][71][72] to construct supramolecular assemblies involving these pincer cations and pyridine-modified peptides [57] and carbohydrates [58], thereby constructing bio-coordination complexes with special properties.…”

Synthesis and ion-binding studies of platinum(II) phenanthroline complexes containing crown ether moiety

“…Keywords: phenanthroline platinum(II) complex, MLCT excited state, benzo-[15]-crown-5 phenanthroline.www.scichina.com www.springerlink.com 1005 ) Square-planar platinum(II) polypyridyl complexes represent an important class of compounds that possess a rich range of spectroscopic and photophysical properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . Some of them have demonstrated promise in wide-ranging applications including optical power limiting [4] , electroluminescence [5,6] , photocatalysts [7][8][9] and multi-electron-transfer processes [10,11] .…”

“…Some of them have demonstrated promise in wide-ranging applications including optical power limiting [4] , electroluminescence [5,6] , photocatalysts [7][8][9] and multi-electron-transfer processes [10,11] . Recently, the design of luminescent sensors for metal ions has been extended to the utilization of platinum(II) polypyridyl complexes, and ion-binding studies of platinum(II) terpyridyl or cyclometalated complex by us [12][13][14] and others [15][16][17] have been reported.…”