Volume 44, Issue 11

The preparation and spectroscopic characterization of the sulfonium salts R 2 SH + MF 6- and RSH 2 + MF 6- (R = CH 3 , t-C 4 H 9 ; M = As, Sb) is reported. The compounds are synthesized by protonation of the corresponding sulfanes in the superacid system HF/MF 5 .

The preparations and characterizations of compounds SCl 2 F + MF 6 ~ (M = As, Sb) are reported. They are yellowish hydrolysable solids, with a strong tendency towards symmetrization in solution. The mass spectra data indicate the formation of SCl 2 F 2 on thermolysis. The series of SCl n F 3-n + -cations (n = 0—3) is now complete, and a comprehensive discussion of the spectroscopic data is given.

The colourless compounds Li 3 OBr and Li 7 O 2 Br 3 have been prepared and characterized by X-ray diffraction techniques. Li 3 OBr crystallizes in a cubic primitive lattice (Pm3m) with a = 405.6(1) pm (Z = 1). The structure is related to the anti-perovskite type. Li 7 O 2 Br 3 crystallizes in a tetragonal bodycentered lattice (I4/mmm) with a = 403.5(1) pm, c = 2161(1) pm (Z = 2) and is isotypic to Sr 3 Ti 2 O7.

Tris(methylseleno)stibane (1) has been prepared by reaction of Sb with Me 2 Se 2 . The crystal structure of 1 consists of (MeSe) 3 Sb molecules with trigonal pyramidal SbSe 3 units (average distances Sb—Se 2.580 Å and Se—C 1.97 A, angles SeSbSe 83-102°). Intermolecular Sb···Se contacts of 3.55-3.66 Å lead to a distorted octahedral coordination at Sb. In the UV-VIS spectrum of the yellow solid of 1 there is a maximum of absorption at 430 nm with a slope to 540 nm. Raman emissions at 204 and 237 cm -1 are related with v s,as SbSe 3 .

The interaction between the VO 2+ cation and a number of nucleotides has been investigated by means of 31 P NMR and IR measurements in solutions. The results support and extend previous conclusions obtained from electronic spectra and confirm the central role of the phosphate groups of the nucleotides in this process. Preliminary results obtained from IR spectra of some solid vanadyl/nucleotide compounds suggest a greater complexity of the metal-to ligand interaction in the solid state.

The melting diagram of the quasibinary system D 2 O— DF was determined by low-temperature DTA and X-ray powder diffraction. It was found to be largely similar to that of the corresponding non-deuterated system H 2 O—HF with the striking exception of an additional phase with a composition of its own, 2D 2 O· 3 DF, and stable between ca. —78 and —71°C. Its structure, determined from single-crystal MoKā diffractometer data at —150°C, is rhombohedral (space group R3c, Z = 6, a = 769.9, c = 1242.1 pm) and strongly related to that of NH, · 4 HF or NH 4 [F(HF) 3 ] with also seven H (as to be compared to D) and five non-H (non-D) atoms per formula unit. But with the O atom involved in four hydrogen bonds, one O · · · O and three O · · · F. at distances of 273.9 and 259.5 pm, respectively, the compound appears to be a molecular adduct rather than an oxonium salt. The D atoms in the hydrogen bonds are distributed over two positions each. — The remaining intermediary phases of the deuterated system, i. e. D 2 O · DF, D 2 O· 2 DF and D 2 O · 4 DF, are isotypic to their protonated counterparts of known crystal structure. For D 2 O · DF and D 2 O-2 DF these results from powder patterns were confirmed by two more single-crystal studies. The ionic structures — D 3 OF and D 3 O[F(DF)], respectively — show no distinctive effect of the H/D substitution even on details of the interatomic geometries.

N-Lithio-N,N′-di(t-butyl)-S-ferrocenylsulfinic acid imidoamide (1) has been synthesized from C 5 H 5 FeC 5 H 4 Li and Bu′NSNBu′. Treatment of 1 with SnCl 4 results in the formation of C 18 H 27 Cl 3 FeN 2 SSn (2), an orange solid containing a four-membered SN 2 Sn ring. Complex 2 crystallizes in the monoclinic space group P2 1 /c with cell constants a = 1035.7(5), b = 1403.7(7), c = 1591.5(8) pm; β = 92.79(3)°.

Cp*TaF 4 (1) (Cp* = η 5 -C 5 Me 5 ) reacts with lithium salts of benzamidines or 1,3-diketones to form hexa-coordinated complexes of composition Cp*TaF 3 [(Me 3 SiN) 2 CPh] (2), Cp*TaF 3 [(Me 3 SiN) 2 C(p-CF 3 C 6 H 4 )] (3) and Cp*TaF 3 (O=CPhCH=CPhO) (4). The reactions proceed under elimination of LiF. The X-ray crystal structure of Cp*TaF 3 (O=CPhCH=CPhO) (4) has been determined shows tantalum to have a distorted octahedral environment, if the Cp* ligand is considered to occupy one coordination site.

The radiolysis of deoxygenated triethylsilane (Et 3 SiH) was studied in the presence of various concentrations of ethylbromide (EtBr) as a function of the radiation dose. Chain reactions are leading to rather high yields of Br-containing final products, e. g. using 0.93 mol/dm 3 EtBr we obtained: G i (Et 3 SiBr) = 138, G i (HBr) = 40, G i (Br 2 ) = 15 and G i (Et 3 Si–SiEt 3 ) = 6, in addition to small amounts of unidentified oligomers. Based on the knowledge from previous steady-state and pulse radiolysis studies of Et 3 SiH, a probable reaction mechanism is postulated to allow explanation of the present results.

The molybdenum nitrido complexes [Na(15-crown-5)][MoNCl 3 ] (1), [Na(15-crown-5)] 2 [MoNCl 4 ] (2), and [Na(15-crown-5)Na(THF)] 2 [MoNCl 3 ·THF] 4 ·2THF (3) have been prepared by reactions of MoNCl 3 with sodium naphthalide in tetrahydrofurane (THF) in the presence of 15-crown-5. According to the EPR spectra and in agreement with the IR spectra, 1 forms dimeric ions [MoNCl 3 ] 2 2 ~ via chloro bridges, whereas tetrameric units [MoNCl 4 ] 4 8 ~ and [MoNCl 3 · THF] 4 4 ~ are present in 2 and 3, respectively. 3 was characterized by an X-ray structure determination: space group P2 1 /c, Z = 2, 1964 observed unique reflexions, R = 0.12. Lattice dimensions at —90 °C: a = 1173(1); b = 2083(3); c = 1750(2) pm; β = 112.3(7)°. The structure consists of an ensemble of associated ions around the central [MoNCl 3 ·THF] 4 4 ~ unit. In the latter, the four Mo atoms form a square and are bridged via linear, asymmetric Mo=N—Mo groups. The (MoN) 4 square is enclosed in a cube of eight Cl atoms, the Mo atoms occupying four of the cube edges. Two Na + ions are situated in the centres of two opposing cube faces, each of the other two Na + ions is coordinated with two Cl atoms outside of the cube; these Na + ions are also coordinated with one THF molecule and with one 15-crown-5 molecule, respectively. The crystal also contains non-coordinated THF molecules, which exhibit strong thermal motion and/or disorder.

[Na-15-crown-5][FX 2 V(N 3 S 2 )] (X = Cl, Br) and [Na-benzo-15-crown-5][FCl 2 V(N 3 S 2 )] have been prepared by reactions of X 2 V(N 3 S 2 ) with sodium fluoride in acetonitrile suspensions in the presence of 15-crown-5 and benzo-15-crown-5, respectively. The 15 N-labeled complex [Na-15-crown-5]-[FCl 2 V( 15 N 3 S 2 )] was also prepared and characterized by 15 N, 19 F, and 51 V NMR spectra, as well as by IR spectroscopy. Whereas the crystal structure of [Na-15-crown-5][FCl 2 V(N 3 S 2 )], owing to disorder of the crown ether molecule, could be refined only to an R-value of 0.16 (space group C2/m, Z = 4, a = 1995.4(11); b = 1016.2(6); c = 1047.2(8) pm; β = 100.83(4)° at —65 °C), the crystal structure of the corresponding [Na-benzo-15-crown-5][FCl 2 V(N 3 S 2 )] was determined without complications. Space group P2,/c, Z = 4, 5565 observed independent reflexions, R = 0.036. Lattice dimensions at 20 °C: a = 1198.9(6); b = 970.3(5); c = 1918.2(10) pm; β = 93.74(3)°. The compound forms ion pairs, in which the sodium atom is seven-coordinated by the oxygen atoms of the crown ether molecule, the fluorine atom and one chlorine atom of the trigonal-bipyramidal [FCl 2 V(N 3 S 2 )] - unit. The vanadium atom is part of a planar VN 3 S 2 ring; fluorine and two nitrogen atoms of the cyclothiazeno ring occupy the equatorial positions.

[Na-15-crown-5][ReF 2 Cl 2 (NO) 2 ] has been prepared by the reaction of ReCl 3 (NO) 2 with sodium fluoride in acetonitrile suspension in the presence of 15-crown-5. It forms green, slightly moisture sensitive crystals, which were characterized by IR spectroscopy as well as by an X-ray structure determination. Space group P2 1 /c, Z = 4, 4821 observed unique reflexions, R = 0.040. Lattice dimensions at —60 °C: a = 1024.6(7), b = 801.4(4), c = 2386.6(12) pm; β = 99.90(4)°. The compound forms ion pairs via two Na—F contacts with bond lengths of 239.8 and 233.4 pm. Thus the sodium ion is seven-coordinate by the five oxygen atoms of the crown ether molecule and by two fluorine ligands of the [ReF 2 Cl 2 (NO) 2 ] - unit. The nitrosyl groups of the anion are in transposition to the fluorine atoms and in cis-position to one another (symmetry C 2v ).

The cesium polyselenide Cs 4 Se 16 has been prepared by the methanolothermal reaction of Cs 2 CO 3 and Se at 160 °C and 13 bar. [Se 16 ] 4- fragments may be regarded as containing an Se 6 ring with C s symmetry and two Se 5 chains related by the crystallographic mirror plane. Se4 of the sixmembered ring, which displays a square planar geometry, participates in two relatively long Se4—Se5 bonds [2.989(4) A] to individual chains. The trans-sited Se4—Se3 bonds [2.425(4) A] are markedly longer than the remaining Se—Se bonds in the Se 6 ring [2.344(4), 2.356(4) A]. Further Se—Se interactions of length 3.132(4) and 3.346(4) Å are observed between individual [Se 16 ] 4- fragments.

By 103 Rh NMR spectroscopy the ten compounds of the system [RhCl„Br 6 _„] 3- , n = 0-6 are identified by separate signals. A downfield shift of approximately 160 ppm is observed per substitution of Cl by Br, and the stereoisomers for n = 2, 3, 4 are separated by at least 4 ppm. From the relative intensities of the 103 Rh signals in equilibrated solutions, whose total contents of Rh. Cl and Br are known, six individual stability constants are calculated. Their product gives the overall stability constant, indicating [RhBr 6 ] 3- to be 36,300 times more stable than [RhCl 6 ] 3- . On treatment of [RhBr 6 ] 3- with HCl cis/fac isomers are formed stereospecifically, whereas the reaction of [RhCl 6 ] 3- with HBr gives trans isomers, n = 2 and 4, containing 20—30% of the cis compounds; only mer-[RhCl 3 Br 3 ] 3- is obtained pure. The high resolution spectra of [RhCl 6 ] 3- and [RhBr 6 ] 3- are exhibit five signals each, reflecting the intensity patterns of the most abundant isotopomers within [Rh 35 Cl n 37 Cl 6-n ] 3 -, n = 2-6, and [Rh 79 Br„ 81 Br 6 _„] 3 -, n = 1-5, respectively.

High-resolution solid state 13 C, 23 Na and 31 P NMR data have been obtained for the acid form and for several salts of the phosphonic acids: ethane-1,2-diphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid (HEDP), and 3-amino-1-hydroxypropane-1,1-diphosphonic acid. The data provide evidence by which sample purity and crystallinity may be examined and from which the size of the asymmetric unit may be determined. In the case of the sodium salts of ethane-1,2-diphosphonic acid, the 31 P and 23 Na spectra provide evidence of possible motion or bond fluctionality for the phosphonic acid group.

Pyrrolidine adds to the isocyano group of Cr(CO) 5 CNCCl 2 CH 2 Cl with concomitant loss of HC1 to give a (1,2-dichloroethylideneamino)(pyrrolidino)carbene complex in which the α-chlorine atom can be replaced by a second molecule of pyrrolidine. Cr(CO) 5 CNCCl 2 H (2) and Cr(CO) 5 CNCCl= CH 2 (4) only afford the respective 1:2 adducts, 4 also with diethylamine. 2 and t-butanethiol react with formation of a (t-butylthiomethylidenamino)(t-butylthio)carbene complex (main product) and Cr(CO) 5 CNCH 2 Cl (side product). The IR spectra of the carbene species show unusual v(CO) patterns. In order to explain the NMR spectra, three different kinds of hindered rotations and a fast nitrogen inversion are proposed.

The reaction of Ν,N′-dimethylurea with 1,5-dimethyl-2,4-bis-(dimethylamino)-1,5-diaza-2,4-dibora-3-oxacyclohexan-6-one (2) in the melt proceeds with condensation of the urea to yield two major products: the acid 1,3,5-trimethyl-2-hydroxy-1,3,5-triaza-2-boracyclohexa-4,5-dione (la); and a mixture of the methylammonium (4 a) and dimethylammonium salt (4b) of the anion [{CH 3 N(u-CONCH 3 ) 2 } 2 B] - . Analogous products were obtained from the reaction of 2 with Ν,Ν′,N″-triorganylbiurets. The 2-hydroxy derivatives of type 1 form 1:1 molar adducts with amines (3) of variable thermal stability. The anhydride of la was obtained as the bis(dimethylamine) adduct [CH 3 N(μ-CONCH 3 ) 2 B] 2 O · 2 (CH 3 ) 2 NH (6) from the reaction of [(CH 3 ) 2 N] 2 BOB[N(CH 3 ) 2 ] 2 with N,N′,N″-trimethylbiuret.

From lattice constants and Mössbauer data the valence distribution and an energy-level diagram of the spinel system Fe(Fe x V 2-x )O 4 have been derived. In the range 0.3 ≦ χ ≦ 1.5 the transition from normal to inverse spinels takes place. The Mößbauer spectra with 1.0 ≦ χ ≦ 2.0 consist of two sets of sextets corresponding to tetrahedral and octahedral sites. Typical values of isomer shift and internal magnetic field strength due to the different environments of the iron ion result from the superimposed sextets of the octahedral site pattern. Neighbouring V ions enhance the conduction electron density and diminish the strength of the magnetic interaction. Mößbauer data, Seebeck coefficients and activation energies lead to a model of both tetrahedral and octahedral conduction based on charge hopping. For Fe 1,9 V 1,1 O 4 there exists only one iron species.

Square-planar alkyne rhodium complexes trans-[RhCl(RC=CCO 2 Me)(PiPr 3 ) 2 ] (4-6) bearing at least one electron withdrawing substituent at the C=C triple bond are prepared from [RhCl(PiPr 3 ) 2 ] (3) and RC=CCO 2 Me. Reaction of 3 with tBuC≡CH gives the isomeric alkyne (7) and alkynyl hydrido (8) rhodium complexes in a stepwise fashion. 8 can be trapped with pyridine to produce [RhH(C 2 tBu)Cl(PiPr 3 ) 2 (NC 5 H 5 )] (10). Thermal rearrangement of 6 (R = H) and 8 leads to the formation of the vinylidene complexes trans-[RhCl(=C=CHR)(PiPr 3 ) 2 ] (9,12) which react with NaC 5 H 5 in THF to give the cyclopentadienyl derivatives C 5 H 5 Rh(=C=CHR)(PiPr 3 ) (13, 14). Reactions of 13 and 14 with sulfur afford the thioketene rhodium compounds C 5 H 5 Rh(η 2 -S=C=CHR)(PiPr 3 ) which on methylation with CF 3 SO 3 CH 3 in the presence of NH 4 PF 6 give the ionic complexes [C 5 H 5 Rh(η 2 -SCH 3 =C= CHR)(PiPr 3 )]PF 6 (18,19).

1:1-Electrolytes of the type [tris(dimethylamino)cyclopropendiylium] 2 + ElX 6 2- have been synthesized for the first time (El = Sn, Te; X = Cl, Br). Analysis of their UV spectra points to a novel OSCT-interaction within these ion pairs in which the complex anion acts as the donor. With 48-electron systems as SnX 6 2- the bromo complex is the better donor than the chloro complex whereas with 50-electron systems TeX 6 2- the reverse behaviour is observed. These contrasting tendencies can be explained by a simple MO model, according to which SnX 6 2- anions interact with the organic acceptor via a HOMO of t lu- symmetry, whereas anions of the type TeX 6 2- employ their a lg *-HOMO.

Quantum-chemical and spectral studies on the protonated form of fluorenone-anil show that this compound has anti-aromatic character. Its real structure should be considered as: 9-amino derivative of the anti-aromatic fluorenium cation.

Oxidation of (3-oxo-camphorsulfonyl)imine (1) by magnesium monoperoxyphthalate does not lead to the oxaziridine obtained with 3-chloro-perbenzoic acid, but to a new chiral oxaziridine containing an additional oxygen atom (Baeyer-Villiger type oxidation). The structure of the product is established by X-ray crystallography, and reaction pathways for the oxidation of 1 by peracids are discussed.

Oxidation of N-alkoxy-2,6- or -2,4-dinitroanilines with various oxidizing agents yields the corresponding N-alkoxydinitrophenyl-aminyls, which then undergo spontaneous conversion into the corresponding N-alkoxy-2,4,6-trinitrophenyl-aminyls. The EPR spectra of all these persistent aminyls are presented and discussed. Such disproportionations did not occur in capto-dative diaryl-aminyls which had lower spin densities on the electron-acceptor group than the present N–alkoxy-polynitrophenyl-aminyls (these have, in addition. Ν—Ο bonds which are less strong than N—C bonds). Electronic structures of diaryl-aminyls and N-alkoxy-aryl-aminyls are discussed: both are π-radicals, but they probably possess at the nitrogen atom an approximately linear, and a kinked structure, respectively.

The complexes of tetravanadate ions with optically active polyols and carbohydrates with suitable steric properties show up to four separate cotton effects in the wavelength range of λ = 200-350 nm. Thus it is possible to classify pyranoses into four groups according to their circular dichroitic behaviour and determine the configuration and the conformation of the hydroxyl groups attached to the pyranose ring.

The structure 2 is established for 5-deoxybostrycoidin, a new metabolite isolated from cultures of the fungus Nectria haematococca (Berk. and Br.) Wr., on the basis of physico-chemical data (MS, 1 H and 13 C NMR, acetylation) and by reference to the known bostrycoidin 1.

Four new spin traps with functionalized acyclic nitrone structures, EtCH(CH 2 CH 2 CO 2 Et)CH=N(O)CMe 3 (3), EtCH(CH 2 CH 2 CH 2 OH)CH=N(O)CMe 3 (4), EtCH(CH 2 CH 2 CN)CH=N(O)CMe 3 (6), EtCH(CH 2 CH 2 CO 2 H)CH=N(O)CMe 3 (10), were prepared and characterized by infrared spectrometry, mass spectrometry and 1 H NMR.