ZEKE-PFI spectroscopy of the Al–(H2O) and Al–(D2O) complexes

The weakly bound complexes Al–(H2O) and Al–(D2O) are prepared with pulsed laser vaporization and studied with single-photon ZEKE-PFI spectroscopy. The spectra consist of progressions in the Al–water stretch in the ground state of the corresponding cations (Al–H2O: ωe+=327.5 cm−1). The origin energy, Al atom ionization potential and the known Al+–(H2O) bond energy produce a neutral Al–(H2O) bond energy of D0=1440 cm−1. Partially resolved rotational structure suggests that the cation complexes have C2v structures, while the neutrals are non-planar. The neutral structure and energetics are consistent with a metal–water coordinate covalent bond, which has been predicted by theory.