Synthesis of thiadiazabicyclane and bis-1,3,5-dithiazinane by cyclothiomethylation of aliphatic diamines with CH2O and H2S

Cyclocondensation of aliphatic diamines with CH₂O and H₂S (1:3:2 ratio, 0 °C) was carried out to give thiadiazabicyclanes and dithiadiazabicyclanes (1:6:4 ratio), which were previously difficult to synthesize. Symmetric α,ω-bis-1,3,5-dithiazinanes were synthesized at 80 °C by this reaction. The stereochemistry of thiadiazabicyclanes was assigned by ¹H and ¹³C NMR spectroscopy and by theoretical DFT calculations, and of bis-dithiazinanes by X-ray diffraction study in the solid state.     

Synthesis of macrocycles incorporating azo‐bis(azofurazan) framework

A series of macrocycles containing four furazan rings bonded by three azo bonds 2, 5 and 7 have been synthesized from the common precursor, 3‐amino‐3′‐nitro(azofurazan) 3 . The macrocycles closure is a result of N?N bond formation at oxidative cyclization of corresponding bis(3‐aminofurazan‐4‐yl) precursors. X‐Ray crystal structures of macrocycles 2, 2 ?AcOH, 11 and 13 are reported.     

Fine structure of the (S(1)<--S(0)) band origins of phthalocyanine molecules in helium droplets

The laser-induced fluorescence (LIF) excitation spectra of free base phthalocyanine (Pc), Mg-Pc, and Zn-Pc molecules in superfluid helium droplets at T=0.38 K have been studied. The spectra reveal the rich vibronic structure of the S(1)<--S(0) electronic transitions. The band origins of the transitions consist of zero phonon lines accompanied by phonon wings, which originate from simultaneous electronic excitation of the molecule and excitation of the collective modes of the helium surrounding it. The phonon wings have discrete structures suggesting localization of some helium atoms in the neighborhood of the molecules. Zero phonon lines of Mg-Pc and Zn-Pc molecules are split into three components, which are separated by 0.2-0.4 cm(-1). Possible mechanism of splitting involves static or dynamic Jahn-Teller interaction of metal-phthalocyanine molecules in the twofold degenerate S(1)((1)E(u)) state with the helium shell.     

Thermochemistry of heteroatomic compounds 22. Enthalpies of combustion and formation of alkyl(aryl)arsines and arsenites in the condensed and gaseous phases

The enthalpies of combustion (ΔH _comb) of five primary, secondary, and tertiary alkyl(aryl)arsines in the condensed state were calculated using the equation ΔH _comb = −385.8–110.3N, where N is the number of bond-forming electrons. The dependence presented is used for the calculation of the enthalpies of combustion of full esters and amidoesters of arsinous acid of noncyclic and cyclic structures. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1042–1043, May, 2007.     

Transfer hydrogenation processes to mu(3)-alkylidyne groups on the organotitanium oxide [Ti(3)Cp*O(3)

The photochemical treatment of mu(3)-alkylidyne complexes [[TiCp*(mu-O)](3)(mu(3)-CR)] (R=H (1), Me (2), Cp*=eta(5)-C(5)Me(5)) with the amines (2,6-Me(2)C(6)H(3))NH(2), Et(2)NH, and Ph(2)NH and the imine Ph(2)C=NH leads to the partial hydrogenation of the alkylidyne moiety that is supported on the organometallic oxide, [Ti(3)Cp*O(3)], and the formation of new oxoderivatives [[TiCp*(3)(mu-CHR)(R'NR")] (R"=2,6-Me(2)C(6)H(3), R'=H, R=H (3), Me (4); R'=R"=Et, R=H (5), Me (6); R'=R"=Ph, R=H (7), Me (8)) and [[TiCp*(mu-O)](3)(mu-CHR)(N=CPh(2))] (R=H (9), R=Me (10)), respectively. A sequential transfer hydrogenation process occurs when complex 1 is treated with tBuNH(2), which initially gives the mu-methylene [[TiCp*(mu-O)](3)(mu-CH(2))(HNtBu)] (11) complex and finally, the alkyl derivative [[TiCp*(mu-O)](3)(mu-NtBu)Me] (12). Furthermore, irradiation of solutions of the mu(3)-alkylidyne complexes 1 or 2 in the presence of diamines o-C(6)H(4)(NH(2))(2) and H(2)NCH(2)CH(2)NH(2) (en) affords [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(6)H(4)NH)] (13) and [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(2)H(4)NH)] (14) by either methane or ethane elimination, respectively. In the reaction of 1 with en, an intermediate complex [[TiCp*(mu-O)](3)(mu-CH(2))(NHCH(2)CH(2)NH(2))] (15) is detected by (1)H NMR spectroscopy. Thermal treatment of the complexes 4-10 quantitatively regenerates the starting mu(3)-alkylidyne compounds and the amine R'(2)NH or the imine Ph(2)C=NH; however, heating of solutions of 3 or 4 in [D(6)]benzene or a equimolecular mixture of both at 170 degrees C produces methane, ethane, or both, and the complex [[TiCp*(mu-O)](3)[mu(3)-eta(2)-NC(6)H(3)(Me)CH(2)]] (16). The molecular structure of 8 has been established by single-crystal X-ray analysis.     

NMR determination of enantiomeric composition of 1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes using Eu(hfc)3

Experimental conditions for determination of enantiomeric composition of 1-substituted 3-aminocarboranes by ¹H and ¹³C NMR spectroscopy using chiral shift reagent Eu(hfc)₃ have been found.     

Trapping H- bound to the nitrogenase FeMo-cofactor active site during H2 evolution: characterization by ENDOR spectroscopy

We here show that the iron-molybdenum (FeMo)-cofactor of the nitrogenase alpha-70(Ile) molybdenum-iron (MoFe) protein variant accumulates a novel S = (1)/(2) state that can be trapped during the reduction of protons to H(2). (1,2)H-ENDOR measurements disclose the presence of two protons/hydrides (H(+/)(-)) whose hyperfine tensors have been determined from two-dimensional field-frequency (1)H ENDOR plots. The two H(+/)(-) have large isotropic hyperfine couplings, A(iso)( )() approximately 23 MHz, which shows they are bound to the cofactor. The favored analysis for these plots indicates that the two H(+/)(-) have the same principal values, which indicates that they are chemically equivalent. The tensors are further related to each other by a permutation of the tensor components, which indicates an underlying symmetry of binding relative to the cofactor. At present, no model for the structure of the iron-molybdenum (FeMo)-cofactor in the S = (1)/(2) state trapped during the reduction of H(+) can be shown unequivocally to satisfy all of the constraints generated by the ENDOR analysis. The data disfavors any model that involves protonation of sulfides, and thus suggests that the intermediate instead contains two chemically equivalent bound hydrides; it appears unlikely that these are terminal monohydrides.     

Magnetic susceptibility of molybdenum trioxide,dioxide and some suboxides

Magnetic susceptibility measurements were done on MoO₃, MoO₂ and some suboxides in between. The mass susceptibilities ×10⁶ for MoO₃, Mo₁₃O₃₈, Mo₉O₂₆, Mo₈O₂₃, Mo₁₇O₄₇, Mo₄O₁₁ and MoO₂ were as follows 0·02, 0·055, 0·11, 0·160, 0·0937, 0·123 and 0·20 respectively. They were all feebly paramagnetic and attempts were made to interpret these data. The effect of temperature on the specific susceptibility was also studied.     

Structural and magnetic properties of iron(II) complexes with 1,4,5,8,9,12-hexaazatriphenylene (HAT)

Reactions of Fe(II) salts with the ligand 1,4,5,8,9,12-hexaazatriphenylene (HAT) led to the isolation and characterization of four new compounds: [Fe3(HAT)(H2O)12](SO4)3.3.3H2O (1), [Fe2(HAT)(SO4)(H2O)5](SO4).2H2O.CH3OH (2), [Fe2(HAT)(SO4)(H2O)5](SO4).3H2O (3), and [Fe3Cl5(HAT)(CH3OH)4(H2O)]Cl (4). Compound 1 crystallizes as a trinuclear cluster in which HAT acts as a tris-chelating ligand. Compounds 2 and 3 are two polymorphs of an infinite one-dimensional structure in which the Fe atoms are coordinated to HAT and then connected into the chain through bridging sulfate anions. Compound 4 exhibits a similar chain structure, but with bridging chloride ligands. The magnetic behavior of the new compounds is indicative of weak antiferromagnetic coupling between the Fe(II) centers through the HAT ligand.