Chlorodifluoroacetyl Isocyanate, ClF2CC(O)NCO: Preparation and Structural and Spectroscopic Studies

Spectroscopic Properties, Conformation and Structure of Difluorothiophosphoryl Isocyanate in the Gaseous and Solid Phase

Difluorothiophosphoryl isocyanate, F2P(S)NCO was characterized with UV/vis, NMR, IR (gas and Ar-matrix), and Raman (liquid) spectroscopy. Its molecular structure was also established by means of gas electron diffraction (GED) and single crystal X-ray diffraction (XRD) in the gas phase and solid state, respectively. The analysis of the spectroscopic data and molecular structures is complemented by extensive quantum-chemical calculations. Theoretically, the Cs symmetric syn-conformer is predicted to be the most stable conformation. Rotation about the P-N bond requires about 9 kJ mol-1 and the predicted existence of an anti-conformer is dependent on the quantum-chemical method used. This syn-orientation of the isocyanate group is the only one found in the gas phase and contained likewise in the crystal. The overall molecular structure is very similar in gas and solid, despite in the solid state the molecules arrange through intramolecular O⋅⋅⋅F contacts into layers, which are further interconnected by S⋅⋅⋅N, S⋅⋅⋅C and C⋅⋅⋅F contacts. Additionally, the photodecomposition of F2P(S)NCO to form CO, F2P(S)N, and F2PNCO is observed in the solid Ar-matrix.

Insights into the Luminescence Thermochromism of a Triarylboron Derivative: The Role of Intramolecular Group Interaction

The organic fluorescent probes for temperature have received increasing interest due to their extremely high spatial and temporal resolution. A few of triarylboron derivatives, as almost the only molecular probes consisting of a single luminophore, have the ability to change their luminescent color at different temperatures. The mechanism of their luminescence thermochromism is controversial. Herein, several spectral experiments, along with time-dependent density functional theory (TDDFT) and coupled-cluster (CC) calculations, are carried out to elucidate the temperature-dependent luminescence. The CC rather than the TDDFT methods give a relatively reasonable explanation for the experimental results. Consequently, the thermochromism is now considered as the result of conformational thermal equilibria that occur in both the excited and ground states. Besides, an unusual conformer with intramolecular excimer characteristic plays a crucial role in the attractive luminescence behavior.

Dichlorophosphanyl isocyanate – spectroscopy, conformation and molecular structure in the gas phase and the solid state

The conformation and structure of dichlorophosphanyl isocyanate, Cl₂PNCO, in both the gas phase and the solid state have been studied.

Dimers of perhaloacetyl cyanides: CClF2C(O)OC(CN)2CClF2 and CF3C(O)OC(CN) 2CF3. preparation, properties, and spectroscopy

The vapor of the new compound 1,1-dicyano-2-chloro-2,2-difluoroethyl chlorodifluoroacetate, CClF2C(O)OC(CN)2CClF2 and of the known 1,1-dicyano-2,2,2-trifluoroethyl trifluoroacetate, CF3C(O)OC(CN)2CF3, were investigated using vibrational spectroscopy tools. The existence of rotational isomerism was confirmed for CClF2C(O)OC(CN)2CClF2 when the matrix isolated compound was examined in combination with the computational results applying quantum chemical models. From the four conformers gauche-syn-gauche, gauche-syn-anti, syn-syn-anti, syn-syn-gauche (the used nomenclature is with respect to the ϕ(ClC-C(O)), ϕ((O)C-OC), and ϕ(OC-CCl) torsion angles, respectively) predicted for CClF2C(O)OC(CN)2CClF2 the first two forms can be evidenced using Ar-matrix IR spectroscopy, with the first one being the most abundant at room temperature. On the other side, the results obtained for CF3C(O)OC(CN)2CF3 reveals the existence of only one syn-syn-anti form. CClF2C(O)OC(CN)2CClF2 melts at -40 °C and its vapor pressure was fitted by the equation ln p = -4732.6 (1/T) + 10.75 (p [Atm], T [K]) in the range -20 to 20 °C. Its extrapolated boiling point is 167 °C. The first ionization potentials occur for CClF2C(O)OC(CN)2CClF2 and CF3C(O)OC(CN)2CF3 at 12.13 and 12.43 eV, respectively, and were attributed to the ejection of electrons formally located at the carbonylic oxygen lone-pair electrons (nO). The proposed interpretation of the photoelectron spectrum is consistent with related molecules reported previously, and also with the prediction of Outer Valence Green's Functions (OVGF).

Chlorodifluoroacetyl isothiocyanate, ClF2CC(O)NCS: preparation and structural and spectroscopic studies

Chlorodifluoroacetyl isothiocyanate, ClF2CC(O)NCS, was synthesized by the reaction of ClF2CC(O)Cl with an excess of AgNCS. The colorless product melts at -85 °C, and its vapor pressure follows the equation ln p = -4471.1 (1/T) + 11.35 (p [atm], T [K]) in the range -38 to 22 °C. The compound has been characterized by IR (gas phase, Ar matrix, and matrix photochemistry), by liquid Raman, by (19)F and (13)C NMR, gas UV-vis, and photoelectron spectroscopy (PES), by photoionization mass spectrometry (PIMS), and by gas electron diffraction (GED). The conformational properties of ClF2CC(O)NCS have been analyzed by joint application of vibrational spectroscopy, GED and quantum chemical calculations. The existence of two conformers has been detected in the gas and liquid phases, in which the C-Cl bond adopts a gauche orientation with respect to the C═O group; the C═O group is in syn- or anti-position with respect to the N═C double bond of the NCS group. The computed ΔG° difference between these two gauche-syn and gauche-anti forms is ΔG° = 0.63 kcal mol(-1) in the B3LYP/6-31G(d) approximation. The most significant gas-phase structural parameters for gauche-syn ClF2CC(O)NCS are re(NC═S) 1.559(2) Å, re(N═CS) 1.213(2) Å, re(N-C) 1.399(7) Å, re(C═O) 1.199(2) Å, and ∠e(CNC) 134.7(13)°. Photolysis of ClF2CC(O)NCS using an ArF excimer laser (193 nm) mainly yields ClF2CNCS, CO, and ClC(O)CF2NCS. The valence electronic properties of the title compound were studied using PES and PIMS. The experimental first vertical ionization energy of 10.43 eV corresponds to the ejection primarily of the sulfur lone-pair electrons of the in-plane nonbonding orbital on the NCS group.