Quenching studies of the excited state of (4,7-diphenylphenanthroline)(1-(ethoxycarbonyl)-1-cyanoethylene-2,2-dithiolato)platinum(II), Pt(Ph[sub 2]phen)(ecda), by aromatic amines and metallocenes and determination of its excited-state reduction potential

Journal Article · Wed Apr 27 04:00:00 EDT 1994 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00087a026· OSTI ID:6768320

Bevilacqua, J M; Eisenberg, R ^[1]

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1. Univ. of Rochester, Rochester, NY (United States)

Rate constants for electron-transfer quenching of the lowest excited state of Pt(Ph[sub 2]phen)(ecda), where Ph[sub 2]phen is 4,7-diphenyl-1,10-phenanthroline and ecda is 1-(ethoxycarbonyl)-1-cyanoethylene-2,2-dithiolate, by a series of neutral amine quenchers have been determined. Also determined are the electron-transfer and energy-transfer quenching rates of the excited complex *Pt(Ph[sub 2]phen)(ecda) by a series of metallocene quenchers. The triplet states of the amine quenchers are relatively high in energy, >62 kcal/mol, compared to the triplet state of Pt(Ph[sub 2]phen)(ecda) at 52 kcal/mol so that electron transfer is the only possible pathway. However, the low triplet-state energies of the metallocene quenchers, 38-46 kcal/mol, permit energy transfer to compete with electron transfer in this system. Marcus analysis of the amine quenchers allows determination of the excited-state reduction potential, E(Pt[sup */-]), of Pt(Ph[sub 2]phen)(ecda) at 0.93 V. E(Pt[sup */-]) is also estimated using the ground-state reduction potential of Pt(Ph[sub 2]phen)(ecda) of -1.24 vs SCE and the crossing point of the emission and excitation spectra of the complex at 2.22 V. This method of estimation yields a value of 0.93 V. E(Pt[sup */-]) in agreement with the value obtained from the quenching studies. The correlation of E(Pt[sup */-]) through the two methods allows estimation of E(Pt[sup */-]) of related Pt(diimine)(dithiolate) complexes.

• OSTI ID: 6768320
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 33:9; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
AMINES
AROMATICS
AZAARENES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
ELECTRIC POTENTIAL
ELECTRON TRANSFER
ENERGY LEVELS
EXCITED STATES
HETEROCYCLIC COMPOUNDS
KINETICS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHENANTHROLINES
PLATINUM COMPLEXES
QUENCHING
REACTION KINETICS
REDUCTION
TRANSITION ELEMENT COMPLEXES