In the chromophore-quencher complex fac-[Re(Aqphen)(CO)(3)(py-PTZ)](+) (Aqphen is 12,17-dihydronaphtho[2,3-h]dipyrido[3,2-a:2',3'-c]-phenazine-12,17-dione; py-PTZ is 10-(4-picolyl)phenothiazine), Aqphen is a dppz derivative, containing a pendant quinone acceptor at the terminus of a rigid ligand framework. This introduces a third, low-lying, ligand-based pi acceptor level localized largely on the quinone fragment. Laser flash excitation of fac-[Re(Aqphen)(CO)(3)(py-PTZ)](+) (354.7 nm; in 1,2-dichloroethane) results in the appearance of a relatively long-lived transient that decays with tau(298K) = 300 ns (k = 3.3 x 10(6) s(-)(1)). Application of transient absorption, time-resolved resonance Raman, and time-resolved infrared spectroscopies proves that this transient is the redox-separated state fac-[Re(I)(Aqphen(*)(-)())(CO)(3)(py-PTZ(*)(+)())](+) in which the excited electron is localized largely on the quinone portion of the Aqphen ligand.
The Diels-Alder reaction of the title quinone 1 with various symmetrical and unsymmetrical dienes in ethanol solution is reported. The cycloaddition takes place, in all cases, across the external quinone double bond affording with cyclopentadiene, buta-l,3-diene and 2,3-dimethylbuta-l,3-diene, the corresponding adducts 3, 4 and 5. The cycloaddition of 1 with 2-methylbuta-l,3-diene and penta-1,3-diene provided 90 : 10 and 65 : 3 5 mixtures of regioisomers 6-7 and 17-1 8, respectively. Enolisation of these adduct mixtures afforded the corresponding anthracenones 10-1 1 and 21 -22.Compounds 11 and 22, the minor components of the anthracenone mixtures, were synthesized from acetylnaphthalenes 14 and 23.The reaction of 1 with (€)-1 -trimethylsilyloxybuta-l,3-diene yielded exclusively adduct 19 and with (€)-1 -methoxybuta-l,3-diene gave a mixture of compounds 28,31 and 32.The regioselectivity of the Diels-Alder reactions of quinone 1 with 2-methylbuta-1.3-diene and penta-l,3-diene is in agreement with that predicted by frontier molecular orbital (FMO) theory. O n the basis of frontier molecular orbital interactions, compound 19 is proposed as the regioisomer generated in the reaction of 1 with the (E) -1 -trimethylsilyloxybuta-1,3-diene.
A systematic quantum mechanical and spectroscopic study has been made for transition metal ions containing d a atomic configurations. Ligand field parameters and spectral data are summarized. For suitable chelates of Co(lll). Rh(lll), Ir(lll), and Pt(lV). the lowest transition is characterized as being of d-d characteristics. with weak and broad structureless bands. For suitable chelates of Ru(1l) and Os(ll), the lowest transition is characterized as being of d-a, characteristics (involving an antibonding orbital of Ir-origin in the ligand), with strong bands showing pure ligand vibrational structure. The competitive nature of d-d vs. d-a, transitions is interpreted for pyridyl chelate of Ir( I 1 I ) showing d-d lowest transitions and an o-phenanthroline chelate of Ir(l1l) reported in the literature as showing d-a, transitions. A general quantum-theoretical rule for chelates of transition metal ions is given. and the applica-
Electronegativity x and hardness 1) for 54 atoms and their positive and negative ions are calculated by means of self-interaction-corrected DFT including correlation terms. The exchange potential energy is treated by local spin density approximation corrected to account for self-interaction effects as suggested by Rae. The highest occupied orbital eigenvalues for ions are identified to the chemical potential p* for positive and negative charged atoms depending upon the developing charge process. Values of xfs and t ) ' for the different ionic species are given for several values of 6. Average values for (x) and (v) in the sense of Mulliken finite formula for neutral atoms are also tabulated and compared with Mulliken values from experimental data. The agreement among them is almost quantitative.
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