“…The distance of 2.46/~ observed in the title compound would correspond to a carbonyl absorption maximum at about 1650 cm -1. According to Leonard (1960) the carbonyl absorption of the title compound is actually strongly solvent dependent: 1666 cm-1 (C6H12), 1656 cm -1 (CC14) , 1641 cm -x (CH3CN), 1631 cm -z (CH2C12), 1613 cm -z (CHC13). The corresponding distances, estimated from Birnbaum's correlation, would cover the range 2.60 to 2.11 A.…”