electronic effects were investigated on the singlet–triplet energy gaps of divalent unsaturated seven- membered ring r2c6h6m (m=c, si, ge, sn, pb, r= –h, -ch3, i-pr , t-bu) at b3lyp/6-311++g** level. all the triplet states of r2c6h6c were more stable than the related the singlet states while all the singlet states of r2c6h6m (m= si, ge, sn, pb, r= –h, -ch3, i-pr , t-bu) were more stable than th...

Electronic effects were investigated on the singlet–triplet energy gaps of divalent unsaturated seven- membered ring R2C6H6M (M=C, Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) at B3LYP/6-311++G** level. All the triplet states of R2C6H6C were more stable than the related the singlet states while all the singlet states of R2C6H6M (M= Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) were more stable than th...

In recent work, thermal energy gaps. AE, it °PUPS gas, Ana; Gibbs free energy gaps, AG.,, between singlet(s) and triplet 0) states of 5.12C3H2C, I m (4 N. P. As and Sb) were calculated and compared with thoseanalogues. MC2113C, (M= CIL N. P. As and Sb) at B3LYIE6-311-NG" level of theory. Our itself showedthat Gibbs free energy gaps. AG, for l uu and 1 p are less than IS and I's, respectively. I...

With the aim of recognizing the steric effects on the silylenic R2C6H6Si structures, DFT calculationsare carried out on 8 structures of R2C6H6Si (where R is hydrogen (H), methyl (Me), isopropyl (i-pro),and tert-butyl (tert-Bu)). These species are at either triplet (t) or singlet (s) states. Singlet–tripletenergy separations ( Me (20.32) > t-Bu (15.92).all singlet states of R2C6H6Si, are more st...

with the aim of recognizing the steric effects on the silylenic r2c6h6si structures, dft calculationsare carried out on 8 structures of r2c6h6si (where r is hydrogen (h), methyl (me), isopropyl (i-pro),and tert-butyl (tert-bu)). these species are at either triplet (t) or singlet (s) states. singlet–tripletenergy separations ( me (20.32) > t-bu (15.92).all singlet states of r2c6h6si, are more st...

Chemical stabilities of six low-energy isomers of C24 derived from global-minimum search are investigated. The six isomers include one classical fullerene (isomer 1) whose cage is composed of only five- and six-membered rings (56-MRs), three nonclassical fullerene structures whose cages contain at least one four-membered ring (4-MR), one plate, and one monocyclic ring. Chemical and electronic p...

The potential energy surfaces for the chemical reactions of group 14 carbenes have been studied using density functional theory (B3LYP/LANL2DZ). Five saturated five-membered-ring N-heterocyclic carbene Dipp[upper bond 1 start]N(CH(2))(2)N(Dipp)E[upper bond 1 end]: (five-ring-E:) species, where E = C, Si, Ge, Sn and Pb, have been chosen as model reactants in this work. Also, four kinds of chemic...

Density functional theory (UB3LYP/6-31G(d,p)) was used to determine substituent effects on the singlet-triplet-state energy gap for 21 meta-substituted phenylnitrenium ions. It was found that strongly electron-donating substituents stabilize the triplet state relative to the singlet state. With sufficiently strong meta electron donors (e.g., m,m'-diaminophenylnitrenium ion) the triplet is predi...

Various isomers of carbo-[3]oxocarbon C9O3 have been characterized on the singlet and triplet spin state potential energy surfaces. Despite its localized structure, the ring carbo-mer of [3]oxocarbon is thermodynamically protected from subsequent isomerization and stable versus dissociation into C3O. It therefore appears as a reasonable synthetic target. In contrast, the less stable tetracyclic...

A series of variable band-gap donor–acceptor–donor (DAD) chromophores capped with platinum(II) acetylide units has been synthesized and fully characterized by electrochemical and photophysical methods, with particular emphasis placed on probing triplet excited state properties. A counter-intuitive trend of increasing fluorescence quantum efficiency and lifetime with decreasing excited state ene...