Medium-ring compounds. XIX. Caprolactam: structure refinement

Abstract

Monoclinic, C2/c, a= 19.28 (2), b= 7.78 (1), c=9.57 (1) A, p= 112.39 (10) °, C6HxlON, M= 113.16, Z=4, D,,=l.12, Dx= 1.133 g cm -3. The previously reported structure has been refined with new threedimensional intensities.

Medium-ring compounds. XX. Caprolactam hydrochloride

“…The chair conformation of the seven-membered ring is very similar to that in unprotonated caprolactam (Winkler & Dunitz, 1975). The only major differences are in the dimensions of the amide group where protonation on O leads to a shortening of 0.07 A in the C(1)-N bond, a corresponding lengthening of 0.07 A in the C(1)-O bond and to changes of 4-5 ° in the bond angles at C(1).…”

Structure of N-nitroso-r-2,c-7-diphenylhexahydro-1,4-diazepin-5-one

“…The geometry around the N(4)---C(5) bond agrees with the dimensions of the standard cis peptide unit (Ramachandran & Sasisekaran, 1968). In the title compound, the amide group adopts the c/s form with a torsion angle of 8.1 (3) ° about the N(4)--C(5) bond which is greater than that determined by Winkler & Dunitz (1975) for caprolactam (-4.1 °) where N(1) of (I) is replaced by C. The presence of the cis form in the present structure is in line with the observation that only nine-and larger membered rings can accommodate torsions of 180 ° about one of the bonds required for the transoid form (Dunitz, 1979).…”

4-tert-Butyl-1-aza-2-cyclohexanone

“…The C(2)-O(2) bond [1.243 (2) AI, instead, is slightly longer rather than shorter when compared to those observed in planar groups: 1.23-1.24 /i, (Ramachandran, Kolaskar, Ramakrishnan & Sasisekharan, 1974;Marsh & Donohue, 1967). The N(1)--C(2) bond length [1.333 (2)/t,] is nearly the same as those values predicted for planar cis-amide bonds: 1.32-1-34 A (Ramachandran & Sasisekharan, 1968;Winkler & Dunitz, 1975). If one compares the present results with a previous study on spirodilactams (Ealick & van der Helm, 1975Ealick, Washecheck & van der Helm, 1976), it appears that the influence on the N-C' and C'-O distances becomes significant only when the non-planarity of the amide group is rather large, that is when ZN ~ 2r _> 10--15 ° The packing of the molecules is by H-bonding around the twofold screw axis [N(1)...O(2)(1-x, ½+y, ½-z) 2.875 A; H(1)...O(2) 2.071 A and N(1)-H(1)...O(2) 155°1, and by van der Waals forces in the a and e directions.…”

“…The torsion angles for the amide (52) 322 (1) 1364 (3) 523 (2) 2.5 (3) H (61) 477 (1) 1319 (3) 491 (2) 3.8 (4) H (62) 398 (1) 1405 (2) 363 (2) 2.0 (3) H (81) 102 (1) 823 (3) 306 (2) 3.3 (4) H (82) 25 (2) 985 (3) 343 (2) 4.2 (4) H (83) 76 (1) 1070 (3) 241 (2) 3.2 (4) n (91) 65 (2) 1306 (3) 481 (2) 4.1 (4) H (92) 123 (2) 1410 (3) 382 (2) 3.9 (4) H (93) 172 (1) 1383 (3) 545 (2) 3.3 (4) H (101) 123 (2) 934 (4) 594 (2) 5.0 (5) H (102) 234 (1) 1013 (3) 639 (2) 3.5 (4) H (103) 197 (1) 789 ( (Johnson, 1965). (Winkler & Dunitz, 1975), which are Xc -0.8 (4) °, ZN 6"5 (30) ° and r --0.6 (15) ° . The results for the present compound are somewhat more accurate and allow the conclusion that the amide bond is non-planar.…”