The First Phenyl-N-pyridinylcarbamate Structures: Structural and Conformational Analysis of Nine Methoxyphenyl-N-pyridinylcarbamates

Abstract

A 3 × 3 isomer grid of nine methoxyphenyl-N-pyridinylcarbamates (C13H12N2O3) as CxxOMe (x = para-/meta-/ortho-) represents the first phenyl-N-pyridinylcarbamate crystal structures to be reported. Structural relationships have been correlated in all nine crystal structures as derived from ab initio calculations and the solid-state using conformational analysis. N–H···N hydrogen bonds dominate as the primary interaction in all nine isomers. Two isomers (CmmOMe, CmoOMe) form unusual cyclic N–H···N trimer synthons as R3 3(15) with two distinct conformations isolated in the CmoOMe structure, whereas the three CoxOMe isomers form N–H···N hydrogen bonded dimers based on the R2 2(8) motif. For all isomers, C–H···O interactions assist in aggregation, and in most cases the methoxy group augments the hydrogen bonding. The solid state and modeled conformations are mismatched in three isomers where the methoxy groups and meta-methoxyphenyl rings (mOMe) (in the solid state) adopt metastable or unstable conformations compared to their optimized computational models. This is rationalized in terms of preferred solid state conformations and observed interactions as compared to the computational models.

At the Interface of Isomorphous Behavior in a 3 × 3 Isomer Grid of Monochlorobenzamides: Analyses of the Interaction Landscapes via Contact Enrichment Studies

“…There is isomorphous overlap between some Clxx structures with their Fxx, 43 NxxF, 44 Mxx 45 or NxxM 46 isomer grid relatives (ESI, Figures S1,S2) and there is also structural similarity with the CxxM and CxxOMe carbamates. 63,64 Computational studies in gas phase are analysed for comparisons directly with the crystal structure results. [43][44][45][46][55][56][57] Only salient features of each Clxx structure are presented, with further information in the ESI (Tables S1, S2a-c).…”

Short C–H⋯F interactions involving the 2,5-difluorobenzene group: understanding the role of fluorine in aggregation and complex C–F/C–H disorder in a 2 × 6 isomer grid

“…[13][14][15][16][17] Ab initio DFT geometry optimisation (B3LYP 32a ; 6-311++G, 32b ) of the twelve compound isomer grid was performed using Gaussian03/09 32c in Please do not adjust margins Please do not adjust margins gas phase (Table 5). These results provide PES diagrams showing the conformational preferences either as (syn-/anti) and rotational barriers in kJ.mol -1 (Figures 7, 8).…”

Two isostructural carbamates: theo-tolylN-(pyridin-3-yl)carbamate and 2-bromophenylN-(pyridin-3-yl)carbamate monohydrates

“…The CmoM C 6 ring is oriented at an angle of 87.83 (4) to the central carbamate moiety which lies at an angle of 25.79 (7) to the C 5 N ring; the corresponding data for CmoBr are 88.60 (11) and 26.67 (18) and highlighting the similarities in the two molecular structures. For comparison, we have previously reported an isomer grid of nine related methoxycarbamates (CxxOMe) (x = ortho-/meta-/para-) in order to compare their crystal structures and molecular models (Mocilac & Gallagher, 2013).…”

“…In the CxxOMe series (Mocilac & Gallagher, 2013), the primary interaction mode for all nine isomers is the amideÁ Á Ápyridine (as N-HÁ Á ÁN) and typically aggregating as catemers, dimers or trimers. However, there is no evidence for the familiar N-HÁ Á ÁO C (amideÁ Á Áamide) type hydrogen bonding (Mocilac & Gallagher, 2013).…”

“…In the CxxOMe series (Mocilac & Gallagher, 2013), the primary interaction mode for all nine isomers is the amideÁ Á Ápyridine (as N-HÁ Á ÁN) and typically aggregating as catemers, dimers or trimers. However, there is no evidence for the familiar N-HÁ Á ÁO C (amideÁ Á Áamide) type hydrogen bonding (Mocilac & Gallagher, 2013). This is in comparison to a series of related benzamides/carboxamides containing one strong donor/two strong acceptors where competition arises resulting in the formation of either (i) N-HÁ Á ÁN or (ii) N-HÁ Á ÁO C hydrogen bonds as the primary strong interaction (Mocilac et al, 2010(Mocilac et al, , 2012.…”