Lowest energy excited states of unsaturated cyclic M[sub 3](dppm)[sub 3]CO[sup 2+] clusters (M = Pd, Pt)

Journal Article · Wed Jan 06 04:00:00 EST 1993 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00053a010· OSTI ID:7072627

Harvey, P D; Provencher, R ^[1]

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1. Universite de Sherbrooke, Quebec (Canada)

The nature of the lowest energy excited states of cyclic unsaturated M[sub 3](dppm)[sub 3]CO[sup 2+] clusters (M = Pd, Pt) has been addressed experimentally using UV-visible, emission, and polarized excitation emission spectroscopy, emission lifetime measurements, and EHMO computations. The 77 K UV-visible spectra exhibit low-intensity features [at 570 nm ([epsilon] = 1,500 M[sup [minus]1] cm[sup [minus]1]; M = Pd) and at 460 nm ([epsilon] = 3,200 M[sup [minus]1] cm[sup [minus]1]; M = Pt)]; they are assigned to singlet-triplet absorptions ([sup 3]A[sub 2], [sup 3]E[l arrow][sup 1]A[sub 1]) on the basis of comparison of the Stokes shifts and [epsilon] values with those for the M[sub 2](dppm)[sub 3] complexes (M = Pd, Pt). The more intense features located at 483 nm ([epsilon] = 43,400 M[sup [minus]1] cm[sup [minus]1]) and 413 nm ([epsilon] = 10,900 M[sup [minus]1] cm[sup [minus]1]) for M = Pd and Pt, respectively, are assigned to the [sup 1]E[l arrow][sup 1]A[sub 1] (a[sub 2][l arrow]e) transitions. The unobserved and forbidden a[sub 2][l arrow]a[sub 1] electronic transitions give rise to the [sup 1,3]A[sub 2] excited states. It was not possible to definitely assign the lowest energy triplet excited states ([sup 3]A[sub 2] or [sup 3]E) on the basis of polarization measurements, but the authors find that these states must like nearby in energy (within a few hundred wavenumbers). No luminescence is observed at room temperature, and the excited lifetimes, measured from flash photolysis measurements, are 80 [plus minus] 10 ns for M = Pd and Pt, respectively. 22 refs., 5 figs., 4 tabs.

• OSTI ID: 7072627
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 32:1; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION SPECTROSCOPY
CALCULATION METHODS
CARBONYLS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
EMISSION SPECTROSCOPY
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
LIFETIME
MOLECULAR ORBITAL METHOD
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PALLADIUM COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PLATINUM COMPOUNDS
POLARIZATION
SPECTROSCOPY
TEMPERATURE EFFECTS
TRANSITION ELEMENT COMPOUNDS