Carbon monoxide with hydrogen-bonding acceptors

IR spectroscopic investigation of intermolecnlar interactions with phenols has a long history. Phenols are freqnently nsed as convenient model proton donors in the study of intermolecularly hydrogen bonded systems. Differently snbstitnted phenols are characterized by a range of different acidities, and complexes can be stndied with a wide variety of proton acceptors. The most commonly adopted acceptors are O and N bases. A special case is carbon monoxide that in complexes with phenols apparently forms ArOH- CO contacts (rather than ArOH- OC). Here we mention some recent investigations with typical proton acceptors like water, alcohols and amines. 

The compound borane-carbonyl occupies a special position in any discussion of molecules derived from boron hydrides with boron-carbon bonds. Carbon monoxide reacts with diborane (20 atm/room temperature) to give an adduct of the borane group which does not rearrange or lose hydrogen (39) The adduct OC BH3 does, however, dissociate into carbon monoxide and diborane at ordinary temperatures. No carbonyls of other Group III acceptor molecules have been prepared so far 133), and it has been suggested 27, 58) that borane-carbonyl owes its existence to the ability of the hydrogen atoms of borane to transfer electrons to a vacant p,-orbital in carbon monoxide. 

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