Physical Chemistry Chemical Physics vol:3 issue:23 pages:5158-5164
date:Univ Louvain, Dept Chem, B-3001 Louvain, Belgium; Univ Technol & Econ, Dept Inorgan Chem, H-1521 Budapest, Hungary; Vietnam Natl Univ, Fac Chem, Coll Sci, Thanh Pho Ho Chi Minh, Vietnam
Structural and electronic features of the linear 1,4-diphosphabutadiyne P=C-C=P and its rhombic isomer were explored using ab initio quantum chemical methods. Portions of the lower-lying [C2P2] potential energy surfaces of both neutral and ionized states were constructed. Geometries, rotational constants, vibrational frequencies, proton affinities and heats of formation of the ground state planar structures were determined using B3LYP and CCSD(T) computations. The vertical excitation and ionization energies were evaluated using the equation of motion EOM-CCSD. Atomic basis sets of different qualities ranging from 6-311 ++ G(d,p) to aug-cc-pV6Z, were employed. Some thermochemical parameters were evaluated as follows: heat of formation at 0 K Delta H-f(0)(PCCP) = 413 +/- 8 kJ mol(-1), adiabatic ionization energy IEa(PCCP) = 9.6 +/- 0.2 eV, proton affinity PA(PCCP) = 715 +/- 8 kJ mol(-1). The heats of formation at 0 K of relevant species are: Delta H-f(0)(CP) = 510 kJ mol(-1) and Delta H-f(0)(HCP) = 225 kJ mol(-1), and the dissociation energies, D-e(H-CP) = 501 kJ mol(-1) and D-e(PC-CP) = 606 kJ mol(-1), with expected errors of +/- 10 kJ mol(-1).