Structure of Liquid N,N-Dimethylformamide Studied by Means of X-Ray Diffraction

Abstract

The structure of N,N-dimethylformamide (DMF) was determined at 25 °C by means of X-ray diffraction using a θ-θ type X-ray diffractometer. The least-squares analysis of the reduced intensities results that a DMF molecule has a practically planar skeletal structure in the liquid state. Intramolecular structural parameters within a DMF molecule were determined as follows: C=O; 1.24 Å, N–C(CHO); 1.35 Å, and N–C(CH3); 1.45 Å. The bond lengths are not appreciably different from those found in the gas phase, except for the C=O length, which is slightly longer by 0.04 Å in the liquid state than in the gaseous one. The radial distribution curve of DMF shows that the intermolecular arrangement of DMF molecules is practically fully disordered and no evidence has been found for the cluster formation of DMF molecules in the liquid state. The experimental result for the weak intermolecular interactions between DMF molecules is supported by ab initio MO-SCF calculations.

X-Ray Diffraction Study of the Solvation Structure of the Cobalt(II) Ion in N,N-Dimethylformamide Solution

“…This indicates that the nitrogen atom is situated trans to the metal atom in the O -C j-N plane. Assuming this geometry, we can estimate the C o-N distance as 425 to 429 pm, close to the experimental one by use of the structure parameters of a DMF molecule (Table 3) [14,[17][18][19] as well as the C o-O and Co-C! distances ( Table 2).…”

“…A preliminary DCo{r) curve obtained by performing the absorption correction with Milberg's original a The angle-dependent error due to the absorption-depen dent effect (see text) is not included. b Assumed; the Cx-H bond length was regarded as 109 pm [18,19] and the H -Q -O angle as 120°. equation [15] lay somewhat lower in the region of 250 to 400 pm, but the peak positions were the same within 1 pm as in Fig.…”

“…The Co(II)-DMF interactions, having a definite configuration in spite of the bulkiness of the DMF molecule and its thermal movement in solution, are [17].c [18]. d [19].e Average values in crystals B and C. inferred to be attributed to the fairly strong and direc tional Co-O bond as well as the fairly rigid and pla nar structure of DMF.…”

A Study of the Liquid Structure of Dimethyl Sulfoxide by the X-Ray Diffraction

“…The arrows indicate the dipole moments. [29]. DMSO has a dipole moment similar to that of DMF, but it has long-range intermolecular interac tions at 25 °C.…”

The Charge Distribution in Amides and Thioamides by Nuclear Quadrupole Coupling, Dipole Moments and Electronic Structure Calculations

“…C 2.5 N 3.0, O 3.5 and S 2.5 all from the Pauling scale [1], but other scales exist with similar interrelationships. Each of the above molecules has a 14 N centre and either a 17 0 or 33 S centre, all being quadrupolar. The gas phase and solid state 14 …”