Structure of Formaldoxime

Abstract

The microwave spectra of cis-CHDNOH, trans-CHDNOH, C13H2NOH, CH2N15OH, and CH2NO18H were assigned. Together with the results of previous work on the normal species and CH2NOD, the data give the following planar structure for formaldoxime: bond lengths in Å; CHcis=1.085, CHtrans=1.086, C=N=1.276, NO=1.408, OH=0.956; bond angles; HcisCN 121°46′, HtransCN 115°33′, CNO 110°12′, NOH 102°41′. The most significant feature of the structure is the difference between cis- and trans-HCN bond angles. This ``tilt'' of the methylene group appears to be too large to be attributed to steric repulsion. The C=N and N–O bond lengths are consistent with the Schomaker—Stevenson relation if allowance for resonance is made.