Potential interstellar molecules. Formation of neutral C6CO from C6CO- in the gas phase

Computations at the RCCSD(T)/aug-cc-pVDZ//B3LYP/6-31G* level of theory indi cate that neutral C6CO is a stable species. The ground state of this neutra l is the singlet cumulene oxide :C=C=C=C=C=C=C=O. The adiabatic electron af finity and dipole moment of singlet C6CO are 2.47 eV and 4.13 D, respective ly, at this level of theory. The anion (C6CO)(-.) should be a possible prec ursor to this neutral. It has been formed by an unequivocal synthesis in th e ion source of a mass spectrometer by the S(N)2(Si) reaction between (CH3) (3)Si-C=C-C=C-C=C-CO-CMe3 and F- to form C-=C-C=C-C=C-CO-CMe3 which loses M e3C in the source to form C6CO-.. Charge stripping of this anion by vertica l Franck-Condon oxidation forms C6CO, characterised by the neutralisation-r eionisation spectrum (-NR+) of C6CO-., which is stable during the timeframe of this experiment (10(-6) s), Copyright (C) 2000 John Wiley & Sons, Ltd.