Bromine principal characteristics

Ab initio calculations on COBtj 2 symmetry) and the asymmetrically substituted carbonyl halides COCIF, COBrF and COBrCl (which have only C, symmetry) have shown that when a bromine atom is present in the molecule, the highest occupied molecular orbital has bromine lone-pair character [1857aa]. In contrast to this, the HOMO of COCIF has mixed chlorine and oxygen character. The principal orbital characteristics for the most chemically significant orbitals of these molecules are given in Tables 17.3 and 17.4 it must be remembered that the low symmetry means that there is little bar to extensive mixing of the molecular orbitals. 

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