K. Sankaran et al., TRIMETHYL PHOSPHATE-WATER INTERACTION - A MATRIX-ISOLATION INFRARED AND AB-INITIO STUDY, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 102(17), 1998, pp. 2944-2953
Trimethyl phosphate (TMP) and water were co-deposited in nitrogen and
argon matrices, and adducts of these species were identified using inf
rared spectroscopy. Formation of the adducts was evidenced by shifts i
n the vibrational frequencies of TMP and water. We computed the struct
ures of these adducts and the vibrational frequencies at the HF/6-31G
level. The computed vibrational frequencies in the adducts involving
the TMP submolecule compared well with the observed frequencies, whil
e the agreement was rather poor for the modes involving the H2O submol
ecule. Both experimental and computational studies indicated that two
types of TMP-water complexes were formed: one in which the hydrogen in
water was bonded to the phosphoryl oxygen of TMP and another in which
the bonding was at the alkoxy oxygen of the phosphate. The stabilizat
ion energy of these adducts, corrected for zero-point energies and bas
is set superposition errors, was computed at both the HF/6-31G*//HF/6
-31G* and MP2/6-31G**//HF/6-31G** levels. Our computations indicated
that both the phosphoryl and alkoxy oxygen bonded TMP-H2O complexes ha
d a cyclic structure determined by a combination of two hydrogen-bonde
d interactions, one involving a hydrogen in water and another involvin
g a hydrogen in the methyl group of TMP.