Experimental and theoretical characterization of the oxygen-coordinated donor-acceptor adducts of COCl2, COClF, and COF2 with AsF5 and SbF5

When reacted with an excess of the corresponding carbonyl halides, AsF5 and SbF5 form the following 1:1 adducts: COCl2. AsF5, COCl2. SbF5, COClF . AsF 5, COClF . SbF5, COF2. AsF5, and COF2. SbF5. All adducts are unstable at am bient temperature, and their dissociation enthalpies were determined from t he dissociation pressure curves. Vibrational and multinuclear NMR spectra a nd theoretical calculations show that all compounds are oxygen-coordinated donor-acceptor adducts, and that the strengths of the oxygen bridges increa se from COF2 to COCl2 and from AsF5 to SbF5. Full normal coordinate analyse s of the adducts demonstrate that the bridging modes occur below 100 cm(-1) , justifying the frequently used approximation of analyzing similar weak ad ducts in terms of their separate donor and acceptor molecules.