An Electron Diffraction Study of Trifluoronitrosomethane

Davis, Michaël I.; Boggs, James E.; Coffey, D. L.; Hanson, Harold P.

doi:10.1021/j100895a012

Cited by 40 publications

(17 citation statements)

References 2 publications

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“…Secondly, bonds b and f are of similar length, while bond c is always much shorter than bond b. Finally, bonds j and k are similar in length, although in simple neutral compounds where there is no possibility of signi®cant electronic delocalization these distances normally differ by at least 0.20 A Ê (Talberg, 1977;Schlemper et al, 1986) and the NO distance rarely exceeds 1.25 A Ê (Davis et al, 1965;Bauer & Andreassen, 1972;Talberg, 1977;Schlemper et al, 1986). These observations taken together con®rm the polarized form (B) as the dominant contributor to the overall electronic structure, rather than the classical charge-localized form (A):…”

Section: Figure 10mentioning

confidence: 99%

Amino-substituted O⁶-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Quesada

Marchal

Bazzicalupi

et al. 2002

Acta Crystallogr Sect B

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The structures of eight 2,4,6-trisubstituted-5-nitrosopyrimidines (one of which crystallizes in two polymorphs) have been determined, including seven O6-benzyl derivatives which are potential, or proven, in vitro inhibitors of the human DNA-repair protein O6-alkylguanine-DNA-transferase. In the derivatives having an amino substituent at the 4-position, an intramolecular N—H...O hydrogen bond with the nitroso O as an acceptor leads to an overall molecular shape similar to that of substituted purines. There is a marked propensity for these nitroso compounds to crystallize with Z′ = 2. The structure of an analogue with no nitroso group is also reported for comparative purposes. Compounds containing the N-alkyl substituents —NHCH2COOEt, —NHCH2CH2COOEt and —NHCH(CH2Ph)COOEt, derived from amino acid esters, exhibit a rich variety of conformational behaviour, and in all of the nitroso compounds the bond lengths provide strong evidence for a highly polarized electronic structure. Associated with this polarization is extensive charge-assisted hydrogen bonding between the molecules, leading to supramolecular aggregation in the form of finite (zero-dimensional) aggregates, chains, molecular ladders, sheets and frameworks.

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Section: Figure 10mentioning

confidence: 99%

Amino-substituted O⁶-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Quesada

Marchal

Bazzicalupi

et al. 2002

Acta Crystallogr Sect B

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“…On the other hand, the bond denoted f is always signi®cantly shorter than the rest of the CÐN bonds, while bond a is always very much longer. Finally, bonds j and k are similar in length, although in simple neutral compounds where there is no possibility of signi®cant electronic delocalization these distances normally differ by at least 0.20 A Ê (Talberg, 1977;Schlemper et al, 1986) and the NO distance rarely exceeds 1.25 A Ê (Davis et al, 1965;Bauer & Andreassen, 1972;Talberg, 1977;Schlemper et al, 1986). These observations taken all together point to the polarized form (A) [see Scheme (II)] as the dominant contributor to the overall molecular-electronic…”

Section: Molecular Dimensions and Conformationsmentioning

confidence: 99%

Supramolecular structures of N ⁴-substituted 2,4-diamino-6-benzyloxy-5-nitrosopyrimidines

Melguizo

Quesada

Low

et al. 2003

Acta Crystallogr Sect B

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The molecular and supramolecular structures of eight N(4)-substituted 2,4-diamino-6-benzyloxy-5-nitrosopyrimidines are discussed, along with one analogue containing no nitroso substituent. The nitroso derivatives all exhibit polarized molecular-electronic structures leading to extensive charge-assisted hydrogen bonding between the molecules. The intermolecular interactions include hard hydrogen bonds of N-H...O and N-H...N types, together with O-H...O and O-H...N types in the monohydrate of 2-amino-6-benzyloxy-4-piperidino-5-nitrosopyrimidine, soft hydrogen bonds of C-H...O, C-H...pi(arene) and N-H...pi(arene) types and aromatic pi...pi stacking interactions. The predominant supramolecular structure types take the form of chains and sheets, but no two of the structures determined here exhibit the same combination of hydrogen-bond types.

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“…An internal rotation constant F" = 2.44 cm-I can be calculated from the known ground state structure (6). If the barriers V, ' and V,", in the excited and ground electronic states respectively, are in phase (eclipsed conformation in both states), the most important transitions form a Au = 0 sequence as would be expected from simple Franck-Condon considerations.…”

Section: Satellite Band Structure and The Barriers To Internal Rotatimentioning

confidence: 99%

“…The ground state structure of CF,NO has been determined by electron diffraction (6). The NO group is eclipsed by one of the CF bonds.…”

Section: Introductionmentioning

confidence: 99%

Conformational changes accompanying electronic excitation of trifluoronitrosomethane

Gordon¹,

Dass²,

Robins³

et al. 1976

Can. J. Chem.

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The 690 nm absorption spectrum of CF3NO has been studied in the gas phase at various temperatures and in the condensed phase at 77 K, and assigned to an (nπ*) transition. Analysis of the vibrational structure shows that, while only the eclipsed conformer is stable in the ground state, there are two stable isomers of comparable energy in the excited electronic state. One has an eclipsed conformation, but with the CF3 group tilted away from the oxygen atom. The other has a staggered conformation. In both of the excited state isomers the barrier to internal rotation is higher than in the ground state.

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An Electron Diffraction Study of Trifluoronitrosomethane

Cited by 40 publications

References 2 publications

Amino-substituted O⁶-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Amino-substituted O⁶-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Supramolecular structures of N ⁴-substituted 2,4-diamino-6-benzyloxy-5-nitrosopyrimidines

Conformational changes accompanying electronic excitation of trifluoronitrosomethane

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An Electron Diffraction Study of Trifluoronitrosomethane

Cited by 40 publications

References 2 publications

Amino-substituted O6-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Amino-substituted O6-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Supramolecular structures of N 4-substituted 2,4-diamino-6-benzyloxy-5-nitrosopyrimidines

Conformational changes accompanying electronic excitation of trifluoronitrosomethane

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Amino-substituted O⁶-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Amino-substituted O⁶-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures

Supramolecular structures of N ⁴-substituted 2,4-diamino-6-benzyloxy-5-nitrosopyrimidines