The electronic structure of two novel binuclear complexes, containing the diradical 6e-bonded mu,mu'-1,2-ethanediyldiamido [mu,-mu'-N(i-Pr)CH2CH2N(i-Pr), hereafter R-EDA] ligand, is discussed by using SCF first-principle discrete variational (DV) X-alpha calculations and gas-phase UV-photoelectron (PE) spectroscopy. The nitrogen-metal interaction has been compared with that computed, within the same theoretical framework, for different isoelectronic complexes where the unsaturated 1,4-diaza-1,3-butadiene [N(i-Pr) = CHCH = N(i-Pr), hereafter R-DAB] ligand acts either as an 8e (sigma-N, sigma-N', eta-2-CN, eta-2-CN') or a 4e (sigma-N, sigma-N' chelating) donor. Such a comparison indicates that different coordinative situations correspond to significantly different bonding schemes, pointing out that the versatile coordination behavior of the saturated (R-EDA)/unsaturated (R-DAB) ligand is a consequence of its "electronic flexibility". In particular, two interesting and unexpected points come out from the analysis of theoretical data. First of all, in both Ru2(CO)6[mu,mu'-N(R)CH2CH2N(R)] and FeRu(CO)6[mu,mu'-N(R)CH2CH2N(R)] complexes, the main source of the M-N bonding is pi in nature, while sigma contributions are very poor. Second, in the former compound, a metal-based t2g-like level actively participates in the Ru-N interaction. Transition-state ionization energies reproduce excellently the experimental PE pattern of the homobinuclear complex while some discrepancy is present between computed and experimental ionization energies in the heterobinuclear one.

EXPERIMENTAL AND THEORETICAL INVESTIGATION OF THE ELECTRONIC-STRUCTURE OF 2 ISOELECTRONIC BINUCLEAR CLUSTERS - UV-PES AND DV-X-ALPHA STUDY OF RU2(CO)6[MU,MU'-N(R)CH2CH2N(R)] AND FERU(CO)6[MU,MU'-N(R)CH2CH2N(R)]

GULINO, Antonino;
1991

Abstract

The electronic structure of two novel binuclear complexes, containing the diradical 6e-bonded mu,mu'-1,2-ethanediyldiamido [mu,-mu'-N(i-Pr)CH2CH2N(i-Pr), hereafter R-EDA] ligand, is discussed by using SCF first-principle discrete variational (DV) X-alpha calculations and gas-phase UV-photoelectron (PE) spectroscopy. The nitrogen-metal interaction has been compared with that computed, within the same theoretical framework, for different isoelectronic complexes where the unsaturated 1,4-diaza-1,3-butadiene [N(i-Pr) = CHCH = N(i-Pr), hereafter R-DAB] ligand acts either as an 8e (sigma-N, sigma-N', eta-2-CN, eta-2-CN') or a 4e (sigma-N, sigma-N' chelating) donor. Such a comparison indicates that different coordinative situations correspond to significantly different bonding schemes, pointing out that the versatile coordination behavior of the saturated (R-EDA)/unsaturated (R-DAB) ligand is a consequence of its "electronic flexibility". In particular, two interesting and unexpected points come out from the analysis of theoretical data. First of all, in both Ru2(CO)6[mu,mu'-N(R)CH2CH2N(R)] and FeRu(CO)6[mu,mu'-N(R)CH2CH2N(R)] complexes, the main source of the M-N bonding is pi in nature, while sigma contributions are very poor. Second, in the former compound, a metal-based t2g-like level actively participates in the Ru-N interaction. Transition-state ionization energies reproduce excellently the experimental PE pattern of the homobinuclear complex while some discrepancy is present between computed and experimental ionization energies in the heterobinuclear one.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/13361
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