Resonance Raman spectra and theoretical studies on 1,3,2,4-benzodithiazines

MAURICIA SCHETTINO; ROSANA M. ROMANO; CARLOS O. DELLA VÉDOVA; ALEXANDER MAKAROV; ANDREY ZIBAREV

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

Año: 2001 vol. 3 p. 1411 - 1418

1463-9076

DFT calculations on 1,3,2,4-benzodithiadiazine (1) and its 5-F (2), 6-Cl (3) and (4) derivatives showed 7-CH3 these compounds to have essentially non-planar molecular conformations. The vibrational (IR and Raman) spectra of 1È4 were measured and assigned on the basis of the results of the theoretical calculations. N2S2N anti-symmetric and symmetric stretching modes were found at D1220È1230 and D965È975 cm~1, respectively. Resonance Raman spectra of 1È4 were obtained with the 514.5, 496.5, 488.0, 476.5 and 457.9 nm excitation lines of an Argon laser, and a post-resonance Raman e.ect was observed. The Raman excitation proÐles revealed a weak but deÐnite p-interaction of the carbocyclic and heterocyclic parts of the molecules which became stronger on going from 1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.1) and its 5-F (2), 6-Cl (3) and (4) derivatives showed 7-CH3 these compounds to have essentially non-planar molecular conformations. The vibrational (IR and Raman) spectra of 1È4 were measured and assigned on the basis of the results of the theoretical calculations. N2S2N anti-symmetric and symmetric stretching modes were found at D1220È1230 and D965È975 cm~1, respectively. Resonance Raman spectra of 1È4 were obtained with the 514.5, 496.5, 488.0, 476.5 and 457.9 nm excitation lines of an Argon laser, and a post-resonance Raman e.ect was observed. The Raman excitation proÐles revealed a weak but deÐnite p-interaction of the carbocyclic and heterocyclic parts of the molecules which became stronger on going from 1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.1È4 were measured and assigned on the basis of the results of the theoretical calculations. N2S2N anti-symmetric and symmetric stretching modes were found at D1220È1230 and D965È975 cm~1, respectively. Resonance Raman spectra of 1È4 were obtained with the 514.5, 496.5, 488.0, 476.5 and 457.9 nm excitation lines of an Argon laser, and a post-resonance Raman e.ect was observed. The Raman excitation proÐles revealed a weak but deÐnite p-interaction of the carbocyclic and heterocyclic parts of the molecules which became stronger on going from 1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.D1220È1230 and D965È975 cm~1, respectively. Resonance Raman spectra of 1È4 were obtained with the 514.5, 496.5, 488.0, 476.5 and 457.9 nm excitation lines of an Argon laser, and a post-resonance Raman e.ect was observed. The Raman excitation proÐles revealed a weak but deÐnite p-interaction of the carbocyclic and heterocyclic parts of the molecules which became stronger on going from 1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.1È4 were obtained with the 514.5, 496.5, 488.0, 476.5 and 457.9 nm excitation lines of an Argon laser, and a post-resonance Raman e.ect was observed. The Raman excitation proÐles revealed a weak but deÐnite p-interaction of the carbocyclic and heterocyclic parts of the molecules which became stronger on going from 1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.p-interaction of the carbocyclic and heterocyclic parts of the molecules which became stronger on going from 1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.1 to 2. Comments on the possible existence of antiaromaticity for the title compounds in a planar conformation are given.