Abstract MeNSOF2 was crystallised by laser-assisted zone refinement at 150 K. The structure obtained by X-ray diffraction initially on cooling to 140 K was triclinic, P-̄, but this transformed slowly to a second phase, which was monoclinic C2/c. Bond distances and angles are similar to equivalent interactions in (MeN)2 SF2 and SO2 F2. Intermolecular interactions in both phases are dominated by dispersion, though electrostatics are also important in all the most energetic contacts. Though no interatomic contacts fall within the sums of van der Waals radii of the contacting atoms, PIXEL calculations indicate that some intermolecular energies are similar to medium-strength hydrogen bonds. The monoclinic phase is denser than the triclinic phase, having stronger dispersion interactions. PIXEL and DFT calculations indicate that the two phases are energetically very finely balanced, but phase I becomes competitive at higher temperature on account of the entropy advantage of its ‘looser’ structure. DFT phonon energy calculations suggest that the mechanism of the transition may involve coupling between acoustic and low energy optical phonons.

CH3-N=SF2=N-CH3 (1) was obtained in 88% yield from the reaction of a bis(silylated) amine RN(Si-Me-3)(2) with a sulfur tetrafluoride imide RN=SF4 (R = R = CH3). Single crystals suitable for X-ray crystallography were obtained by low-temperature crystallization; the data were collected at 120 K. Compound 1 crystallizes in the monoclinic space group P2(1)/c with a = 5.8356(7) angstrom, b = 12.1665(14) angstrom, c = 8.1488(8) angstrom, = 110.381(7)degrees, Z = 4, in the anti-anti form (whereby anti or syn describe the orientation of the N-CH3 bonds with respect to opposite S=N bonds). The structural, conformational, and configurational properties of CH3-N=SF2=N-CH3 were studied by vibrational spectroscopy [IR (gas) and Raman (liquid)] and quantum chemical calculations [B3LYP and MP2 with 6-311+G(2df,p) and cc-pVTZ basis sets]. Vibrational spectroscopy in the gas and liquid phases shows evidence of a configurational equilibrium of the anti-anti form and a slightly less favored anti-syn form of CH3-N=SF2=N-CH3.

The structural, conformational, and configurational properties of 1,1,1-trifluoro-N-(1,1,2,2,2-pentafluoroethyl) methanesulfinimidoyl fluoride, CF3CF2N=S(F)CF3 have been studied by vibrational spectroscopy [IR (vapor) and Raman (liquid)] and quantum chemical calculations [B3LYP, MP2 and B3PW91 levels of theory (using the 6-311+G(d) and 6-311+G(2df) basis sets). According to these theoretical approximations, CF3CF2N=S(F)CF3 might be found in the gas phase as a mixture of a favoured anticlinal form (C-N bond anticlinal with respect to the C-S-F bisector angle) and a less abundant syn conformer showing C1 symmetry as well (ΔG°≈1.5 kcal mol(-1)). However, corresponding vibrational modes for these conformers show only small shifts which would not allow confidently detecting the rather small contribution of this second form in the experimental spectra.

Seit einiger Zeit werden von uns Synthesen, Strukturen und Bindungsverhältnisse in Triazinen (RAN ) 3 intensiv untersucht. Ringsysteme mit RA = RC, RS, RS(O) und R2P sind seit längerem bekannt. Bemerkenswert an dieser Verbindungs­ klasse ist, daß sich die einzelnen Bausteine RA nahezu beliebig wechselseitig austauschen lassen. Uns interessieren vor allem die aus verschiedenen Fragmenten zusammengesetzten ringhalogenierten Heterocyclen (XAN)„(XA'N)3_„ (XAN # X A 'N = XC, XS, XS(O), X2P mit X = Cl, F), da an ihnen die unterschiedliche Reaktivität der einzelnen Bausteine vergleichend untersucht und ihr spezifi­ scher Einfluß auf Struktur und Reaktivität ermit­ telt werden kann. Vor kurzem haben wir ausführ­ lich über Trichlorthiatriazine (C1CN)„(C1SN)3_„ (n = 0 -3 ) [1] und über Oxotrithiatriazine (C1SN)„(C1S(0)N)3_„ [2, 3] berichtet. Perhalogenothiatriazine (XCN)„(X S(0)N)3_„ sind bisher nicht bekannt. In dem letztgenannten System soll­ ten Strukturund Bindungsverhältnisse denen der isoelektronischen Phosphinine (Phosphatriazine) (C1CN)„(C12PN)3_„ sehr ähnlich sein. In der vorliegenden Arbeit wird über die rönt­ genographisch ermittelten Strukturen der bereits aus der Literatur bekannten Verbindungen (C1CN)2(C12PN) (1) [4] und (C1CN)(C12PN ) 2 (2) [5] berichtet. Die Bindungsverhältnisse werden auf der Basis von MNDO-Rechnungen diskutiert

An efficient synthetic method for the preparation of TAS tris(pyrazolyl)methylthiolate (3) is reported. Nucleophilic exchange reactions with 3 gave (pyr)C(=S)SC(pyr)(3) (4) and MeSC(pyr)(3) (5). 5 acts as scorpionate ligand in [MeSC(pyr)(3)Cr(CO)(3)] (6), from the decomposition of TDAE(2+) [SC(pyr)(3)Mo(CO)(3)(-)](2) by SO2FCl TDAE(2+)[O=MoF4F-Mo(=O)Cl-4](2-) (8) was isolated. The X-ray structures of 3-6 and 8 are discussed.

The reaction of 2,3-diaminomaleonitrile with TeX4 (X = Cl, Br) in the presence of pyridine (Py) and/or triethylamine (Et3N) provided 3,4-dicyano-1,2,5-telluradiazole (1), which was isolated neat and as stable adducts with pyridine, chloride, and bromide, namely, 1.2Py, (PyH)(1.Cl), (PyH)2(1.2Cl), (Et3NH)(1.Cl), (PyH)(1.Br), and (PyH)2(1.2Br). The molecular and supramolecular structures of these compounds were investigated by X-ray crystallography. In the solid state, intermolecular associations through secondary Te...N interactions as well as NH...X and NH...N hydrogen bonding (X = Cl, Br) were observed. For (PyH)(1.Br), two polymorphs were found. The bonding situation of 1 and its pyridine and chloride adducts were investigated by MP2 calculations supplemented with the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The p symmetry of the frontier molecular orbitals (MOs) of 1 are preserved in the 1.2Py, (1.Cl), and (1.2Cl) adducts. In the chloride adducts, the highest occupied molecular orbital (HOMO) can be described as an antibonding combination of the HOMO of 1 with the 3p atomic orbitals (AOs) of the chloride ions, whereas the lowest occupied molecular orbital (LUMO) resembles that of the parent 1. The charge transfer onto the heterocycle in the adducts increases in the order 1.2Py, (1.2Cl), and (1.Cl). QTAIM analyses of the adducts in the gas phase reveal closed-shell interactions, whereas NBO analyses indicate negative hyperconjugation as the main formation pathway in these complexes. This description agrees with the Alcock model suggested for secondary bonding interactions between atoms of heavy p-block elements and atoms with lone pairs.

According to the DFT calculations, [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (4), [1,2,5]selenadiazolo[3,4-c][1,2,5]thiadiazole (5), 3,4-dicyano-1,2,5-thiadiazole (6), and 3,4-dicyano-1,2,5-selenadiazole (7) have nearly the same positive electron affinity (EA). Under the CV conditions they readily produce long-lived π-delocalized radical anions (π-RAs) characterized by EPR. Whereas 4 and 5 were chemically reduced into the π-RAs with thiophenolate (PhS(-)), 6 did not react and 7 formed a product of hypercoordination at the Se center (9) isolated in the form of the thermally stable salt [K(18-crown-6)][9] (10). The latter type of reactivity has never been observed previously for any 1,2,5-chalcogenadiazole derivatives. The X-ray structure of salt 10 revealed that the Se-S distance in the anion 9 (2.722 Å) is ca. 0.5 Å longer than the sum of the covalent radii of these atoms but ca. 1 Å shorter than the sum of their van der Waals radii. According to the QTAIM and NBO analysis, the Se-S bond in 9 can be considered a donor-acceptor bond whose formation leads to transfer of ca. 40% of negative charge from PhS(-) onto the heterocycle. For various PhS(-)/1,2,5-chalcogenadiazole reaction systems, thermodynamics and kinetics were theoretically studied to rationalize the interchalcogen hypercoordination vs reduction to π-RA dichotomy. It is predicted that interaction between PhS(-) and 3,4-dicyano-1,2,5-telluradiazole (12), whose EA slightly exceeds that of 6 and 7, will lead to hypercoordinate anion (17) with the interchalcogen Te-S bond being stronger than the Se-S bond observed in anion 9.

Slow evaporation in air of the solution of trimeric perfluoro- ortho -phenylene mercury ( 1 ) and 2,1,3-benzothiadiazole ( 2 ) in THF affords a complex l.2 2 ·H 2 O 0.59 ( 3 ). A complex of 1 with di(tetrahydrofur-2-yl) ether ( 4 ; probably, a THF oxidation product) with a composition of 1.4 2 ( 5 ) is detected as a minor admixture to 3 . The structure of complexes 3 and 5 is determined by single crystal XRD. In complex 3 , a molecule of 1 participates in Hg…N and π F …H—C interactions with one molecule of 2 and in the π F …π H stacking interaction with another. Complex 5 is formed by Hg…O interactions with the participation of both heterocycles of a molecule of 4 .

Decamethylchromocene, Cr(II)(eta(5)-C(5)(CH(3))(5))(2) (2), readily reduced [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (1) in a tetrahydrofuran solvent at ambient temperature with the formation of radical-anion salt [2](+)[1](-) (3) isolated in 97% yield. The heterospin salt 3 ([2](+), S = 3/2; [1](-), S = 1/2) was characterized by single-crystal X-ray diffraction as well as magnetic susceptibility measurements in the temperature range 2-300 K. The experimental data together with theoretical analysis of the salt's magnetic structure within the CASSCF and spin-unrestricted broken-symmetry (BS) density functional theory (DFT) approaches revealed antiferromagnetic (AF) interactions in the crystalline 3: significant between anions [1](-), weak between cations [2](+), and very weak between [1](-) and [2](+). Experimental temperature dependences of the magnetic susceptibility and the effective magnetic moment of 3 were very well reproduced in the assumption of the AF-coupled [1](-)...[1](-) (J(1) = -40 +/- 9 cm(-1)) and [2](+)...[2](+) (J(2) = -0.58 +/- 0.03 cm(-1)) pairs. The experimental J(1) value is in reasonable agreement with the value calculated using BS UB3LYP/6-31+G(d) (-61 cm(-1)) and CASSCF(10,10)/6-31+G(d) (-15.3 cm(-1)) approaches. The experimental J(2) value is also in agreement with that calculated using the BS DFT approach (-0.33 cm(-1)).

Dimethyl(trimethylsilyl)phosphane (Me3SiPMe2) successfully used for the substitution of fluorine variously in 1,3- (1) or 1,2-difluorobenzene (2) or in 1,3,5- (3) or 1,2,3-trifluorobenzene (4) by the Me,P group at 150-190 'C either in benzene solution or without solvent to give 1-(dimethylphosphanyl)-3-fluorobenzene (5) from 1, 1-(dinietliylphosphanyl)-2-flLiorobenzene (6) from 2, 1-(dirnethylphosphanyl)3,5-dilluorobenzene (7) from 3 or a 1:1. mixture of 1-(dimethyll)hosphanyl)-2,3-difluorobenzene (8) and 1-(dimethylphosphanyl)-2,6-difluorobenzene (9) from 4. The substrate selectivities and regioselectivities exhibited by 4 with Me:jS'pMe2 and in competitive reactions between 1 and 2 or 3 and 4 with Me3SiPMe2 Me3SiPMe2 or Me2PLi indicate relative fluorine SUbstituent rate factors f(o-F) > f(m-F) whereas for reactions that proceed through a two-step SNAr mechanism the opposite sequence is typical. High-level quanturrl-chemical DFT and MP2 calculations predict that the gas-pliase reactions stiould each proceed by a concerted mechanism with a single transiLion state. These predictions are in good agreement with the experimental observations, especially because the ArLICtUral features of the Nleisenhenner adduct are unfavourable for the S1,,Ar mechanism. This proposal is consistent with the of)servation of the opposite sequence (f(o-F) > f(m-F)) for the reactions between the same substrates and MeON[a in DIVISO/ CH3OH solvent mixtures. The novel phosphanes were characterized by spectroscopic (NMR) and spectrometric (MS) investigation, preparation of the tbiophosphanes ArFPSI\,Ie,, 10-12, their spectroscopic data and, in the case of 12, by its X-ray structure. The phosphanes 5-9 were treated with I)is(beiizonitrile)dichlorol)alladiiiiii(II) to afford the corresponding bis(phosphane)palladjUln dichloride complexes 17-21 and 23 in isolated yields of up to 95'Y-

Institute of Organic Chemistry, Institute of Inorganic Chemistry, Institute of Chemical Kinetics & Combustion, and International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia, Department of Physics, Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia, and Institute for Inorganic and Physical Chemistry, University of Bremen, Bremen, Germany

The vibrational spectra of pentafluoroethyliminosulfur difluoride, CF3CF2NSF2, were recorded in the gas phase with IR spectroscopy and in the liquid state with Raman spectroscopy. Quantum chemical calculations at the B3LYP (6-311+G(d) and 6-311+G(2df) basis sets) and MP2 levels of theory (6-31+G(d) and 6-311G(d) basis sets) were performed. According to all calculations the lowest energy conformer possesses C1 symmetry with syn orientation of the SF2 group relative to the CN bond and near-trans orientation of the CF3 group relative to the NS bond (syn-trans). Calculations predict the hypothetical presence of a second stable conformer with anti-orientation of the SF2 group (anti-trans) which, however, possesses considerably higher energy and is therefore not observed in the analysis of the experimental spectra. The vibrational spectra were assigned for a single conformer in agreement with these calculations.