Effect of Alkyl Substituents on the Hydrogen Bonding and Molecular Structure of Benzophenylhydroxamic Acids Crystal structure of UO2 Complex of p-Isopropylbenzophenylhydroxamic Acid

The effect of alkyl substituents on the C-phenyl and/or the N-Phenyl ring of benzophenylhydroxamic acid on their molecular structure and hydrogen bonding has been investigated. The predominant configuration in CHCl3 is determined by steric and electronic effects. Substituents on the C-phenyl ring favor the cis configuration, while substituents in the N-phenyl ring favor a trans configuration. These can be rationalized on the basis of electronic effects. Bulky substituents in the C-phenyl ring give rise to a mixture of cis and trans forms due to steric factors. When substituents are present on the C-phenyl ring and N-phenyl ring the trans configuration is preferred. The crystal and molecular structures of  complex of p-isopropylbenzophenylhydroxamic acid have been determined from a single crystal of this complex to elucidate the effect of complexation on the structure of this ligand which exists as a cistrans mixture. Complexation occurs exclusively from the cis configuration.