Singlet-triplet energy gap in halogen-substituted carbenes and silylenes: a difference-dedicated configuration interaction calculation

Abstract

Ab initio calculations including correlation energy are reported on a series of halogen-substituted carbenes and silylenes: CH 2, CHF, CF 2, CHC1, CC12, CHBr, CBr2, Sill2, SiHF, SiF2, using the difference-dedicated configuration interaction method. All these compounds with the exception of CH 2 have singlet ground states. The singlet-triplet energy differences are in very good agreement with experiment when available, as well as with other high level calculations. The singlet-triplet separation is also determined in trifluoromethyl carbenes, CHCF3, CFCF3, CCICF 3 and CBrCF 3. The CF 3 substituent has little influence on the energy gap since CHCF 3 like CH 2 has a triplet ground state, with a gap of 11"1 kcal mo1-1, and CFCF~, CCICF 3 and CBrCF 3 have singlet ground states, like CHF, CHCI and CHBr, with gaps of -17.6, -5"4, and -3"5 kcal mo1-1.

Single vibronic level emission spectroscopy of the system of bromochlorocarbene

“…Calculations predict a singlet ground state for both, with DE ST $ 20 kcal mol À1 ($7000 cm À1 ) for CCl 2 [19, and $17 kcal mol À1 ($5900 cm À1 ) for CBr 2 [30][31][32]34,35,[38][39][40]42,44,46,47]. In contrast, the photoelectron studies of Lineberger and coworkers [7,9] place the singlet-triplet splitting at 3(±3) kcal mol À1 for CCl 2 and 2(±3) kcal mol À1 for CBr 2 [9].…”

The DDCI Method Applied to Reactivity: Chemiluminescent Decomposition of Dioxetane

“…In this case it is more difficult to decide what size the active space should be for the method to perform well at a moderate cost. For this reason, three different active spaces, (4,4), (8,8), and (12,12), were used to calculate the energies of the TS 1 and TS 2 structures on the ground-state surface. The results (Table 3) show that the oscillating convergence within the chemical precision limits, typical of this method, is reached.…”

Mid-Infrared Diode Laser Spectroscopy ofX̃1A′ HC35Cl

“…We thank an anonymous referee for pointing out the existence of reference (16) and for making several other useful suggestions. This work was carried out under Contract DE-AC02-76CH00016 with the U. S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences.…”