Volume 45, Issue 8

The mixed halogenohexaborates B 6 X n Y 6-n 2- , n = 1-5; Χ ≠ Υ = Cl, Br, I, including most of the pure stereoisomers for n = 2—4, are prepared for the first time by treatment of the halohydrohexaborates B 6 X n H 6-n 2- , X = Cl, Br in aqueous alkaline solution with bromine and iodine or with halogenosuccinimides. The point symmetry is determined from the "B NMR spectra, which show characteristic features for homologous isostructural compounds. In the systems B 6 X n Y 6-n 2- a considerable dispersion of the 11 B signals is observed, for B(X) atoms to lower, for B(Y) atoms to higher field compared with B 6 X 6 2- and B 6 Y 6 2- (electronegativity X > Y), respectively. An additional chemical shift is caused by the mutual antipodal effect between pairs of opposite B atoms carrying different substituents. From the systematic influences on the chemical shifts the 11 B NMR spectra of the missing species fac-B 6 X 3 Y 3 2- are calculated.

Single crystals of (n-C 4 H 9 ) 4 NAu(CN) 2 were obtained by crystallization using the temperature decreasing method in a newly developed computer-controlled apparatus. The colourless crystals are monoclinic, space group A2/n, with a = 20.216(2) Å, b = 13.130(1) Å, c = 9.328(1) Å, and β = 109.69(1)°. The measured density is 1.45 g/cm 3 , which agrees with the calculated density of 1.40 g/cm 3 for Ζ = 4. The structure was solved by Direct Methods using 674 independent reflections and refined by least-squares procedures to conventional and weighted R factors of 0.068 and 0.058, respectively. The nearly linear [Au(CN) 2 ] - -anions form pseudohexagonal layers, in which they are arranged parallel to each other. The shortest Au—Au distance is 8.05 A. The stacking of the layers produces pseudo-trigonal channels, occupied by the cations. The tetra-n-butylammonium cation has four ordered trans chains with idealized D 2d symmetry (4̄2 m).

A number of boron spirochelates of the general formula B[R′CON(R)O]Y have been synthesized by the single-pot reaction of boric acid, a hydroxamic acid R′CON(R)OH and a carboxylic acid H 2 Y. The spirochelates have been characterized by elemental analyses, by IR, NMR ( 1 H and 11 B) and UV spectra and conductance measurements. They are non-electrolytes.

(PPh 4 ) 4 [Cu 2 Se 14 ] has been prepared by the reaction of a lithium polyselenide solution in DMF with CuCl at 120 °C in the presence of PPh 4 Br. The compound forms black crystals, which were characterized by IR spectroscopy as well as by an X-ray structure determination. Space group P 2 1 , Z = 2, 2690 observed unique reflexions, R = 0.095. Lattice dimensions at 19 °C: a = 2139.5(9), b = 1611.7(3), c = 1365.1(3) pm, β = 93.54(3)°. The compound consists of PPh 4 + and [Cu 2 Se 14 ] 4- ions, in which the two copper atoms are bridged by an Se 5 2- chain. One of the Cu atoms is a member of a CuSe 4 ring, the other one of a CuSe 5 ring; the coordination at each Cu atom is trigonal-planar.

The infrared spectra of a series of cadmium substituted calcium hydroxylapatites of the type Ca 10-x Cd x (PO 4 ) 6 (OH) 2 , were investigated in order to obtain insight on the effect of the Cd(II) ion on the vibrational properties of the PO 4 3- and OH - groups. The effect of the substitutional process on the strength of the P–O bonds was also checked by Raman Spectroscopy and an analysis of the behaviour of the deuterated Ca 5 Cd 5 (PO 4 ) 6 (OD) 2 phase was undertaken. The strength of the P–O bonds shows a linear dependence on the Cd(II) content, whereas the OH-vibrational modes present a more complex behaviour.

Double hydroboration of allene with HBCl 2 · OEt 2 /BCl 3 leads to 1,3-bis(dichloroboryl)-propane 1 a, in which two chlorine atoms can be substituted by HN(iPr) 2 to give 1 b. Dehalogenation of 1 b with Na/K alloy yields the 1,2-diborolane 2b. Attempts to synthesize an unsaturated 2,3-dihydro-1,2-diborole 4 failed. 1 a and (Me 3 Si) 2 S react to give the 1,2,6-thiadiborinane 6 a, and 1 b and Me 3 C – NH 2 yield the 1,2,6-azadiborinane derivative 7b.

The structure of the reaction product of white phosphorus and sodium in diglyme which exhibits a low field AB 2 system in the 31 P{ 1 H} NMR spectrum [4] has been reexamined. According to the results of a complete analysis of its proton coupled 31 P NMR spectrum (ABB′XX′ system), the compound is the hitherto unknown 1,2,3-triphosphacyclopentadienide ion P 3 (CH) 2 ⊖ (4), and not the triphosphacyclobutenide ion P 3 CH 2 ⊖ (3) previously assumed [4]. The parameters of the Ρ,Η-coupled 31 P NMR spectrum of the tetraphosphacyclopentadienide ion P 4 CH ⊖ (2) have also been calculated.

Gas electron diffraction data of (CH 3 ) 6 Sn 2 and (CH 3 ) 2 Te 2 are consistent with molecular models of D 3 and C 2 symmetry and bond distances Sn–Sn = 277.6(3) pm and Te–Te = 268.6(3) pm, respectively.

The lithium derivate of the octamethylcyclotetrasilazane 1 reacts with fluorosilanes with substitution (2) or substitution and contraction to give cyclotrisilazanes (3—6). Lithiated 6 again reacts with substitution (7, 11, 12) or substitution and isomerization to give 1,3-(Si–N–Si) substituted cyclodisilazanes (8, 13). Starting with the dilithiated eight membered ring (14) the reactions with fluorosilanes lead to the formation of the unsymmetrically 1-(Si)-3-(Si – N – Si – N –Si)-substituted four membered rings (9, 10). The isomerization of the lithium salts depends on thermal, thermodynamic and kinetic effects.

In crystallization experiments for silver borate hydrates from solutions of borax, boric acid, and silver nitrate, a mixture of sborgite and a second modification — named by us “β-sborgite” — have been found besides excess H 3 BO 3 and a microcrystalline silver borate. Both modifications contain the same distorted pentaborate ion [B 5 O 6 (OH) 4 ] - . Both Na + ions in the asymmetric unit are in special positions along the binary axis; one, Na(1), is octahedrally coordinated by four H 2 O molecules and two OH groups, the other one, Na(2), is tetrahedrally coordinated by two H 2 O molecules, two OH groups and — at longer distances — with two bridging oxygen atoms of the pentaborate unit. The different angles — only a small rotation on the b-axis — of the pentaborate anions between an identical matrix of Na-cations give rise to the two different modifications.

The reaction of NaReO 4 with thiobenzoylhydrazine yields Re(NHNC(S)Ph) 3 - DMF (1). With ReOCl 3 (PPh 3 ) 2 thiobenzoylhydrazine reacts to give Re(NHNC(S)Ph) 3 · OPPh 3 (2) and in the presence of HCl to yield [Re(NHNC(S)Ph)(NHNHC(S)Ph),]Cl · 1/3 C 2 H 5 OH -1 /3 H 2 O (3). The structures of 1-3 have been determined. 1: monoclinic, space group P2,/c, a = 1150.1(9), b = 2050.0(9), c = 1181.0(8) pm, β = 109.62(5)°, Z = 4, 2980 reflections, R = 0.055; 2: trigonal, space group R 3, a = 1399.8(1), c = 1684.0(1) pm, Z = 3, 1419 reflections, R = 0.033; 3: monoclinic, space group P2,/c, a = 1446.8(3), b = 3220.7(5), c = 1727.1(4) pm, β = 108.42(2)°, Z = 12, 6112 reflections, R = 0.062. In 1 and 2 three N,S-chelating ligands NHNR (R = C(S)Ph) are coordinated to the central rhenium atom. The ligand structure is intermediate between a diazene and a hydrazido(2–) structure. In 3 each rhenium atom is coordinated by one NHNR and two NHNHR ligands, all N,S-chelating. The latter can be considered as protonated diazene ligands. The unit cell contains three isomeric coordination polyhedra.

The reaction of λ 5 Ρ – λ 3 Ρ diphosphorus compounds with o-quinones, e.g. tetrachloro-o-benzoquinone or 2,5-di-tert-butyl-o-benzoquinone, led not only to oxidative addition of the o-quinone to λ 3 Ρ but also to insertion of a further molecule of o-quinone into the P–P bond (i.e. λ 5 Ρ – λ 3 Ρ diphosphorus compound and o-quinone reacted in a molar ratio 1:2). In the course of these oxidative addition and insertion reactions the o-quinones were converted into the corresponding hydroquinones (i.e. catechols). The products of these reactions were characterized by NMR and mass spectrometric methods, and by elemental analysis. The hydrolysis of the 1:2 addition products proceeded with cleavage of a P–O–C (hydroquinone) bond and formation of mononuclear products, involving λ 4 Ρ and λ 5 Ρ, respectively. A mechanism of this hydrolysis is proposed and has been elucidated by independent synthesis of some products. Diphosphines, i.e. symmetrical λ 3 Ρ – λ 3 Ρ diphosphorus compounds, were found to react with o-quinones in the same fashion in a molar ratio 1:3, i.e. with oxidative addition of the o-quinone to both λ 3 P atoms and insertion of tetrachloro-o-catechol into the P–P bond.

Perhalogeno disulfenes (dimeric thione-S,S-dioxides) (2 a, b) are singly cleaved by TAS–fluoride forming the intermediate salts 3a and 3b. From both anions a fluoride ion can be abstracted by silicon tetrafluoride and the perhalogenated mesylsulfenes X 3 C — SO 2 — C(X)= SO 2 (4 a) (X = Cl) and (4b) (X = Br) could be obtained, which are stabilized by S-coordinated quinuclidine. Hydrolysis occurs to 4 a, b forming the sulfonium salts 7a, b, which are the structural isomers to the sulfonium salts 5 a, b achieved from direct hydrolysis of 2 a, b in the presence of quinuclidine.

[Hg 2 (p-SC 6 H 4 NO 2 )]NO 3 is formed by the reaction of p-nitrothiophenol with dimercury(I)-dinitrate in methanol. It crystallizes in the monoclinic space group P2 1 /n with a = 1175.5(9) pm, b = 1079.8(8) pm, c = 876.2(8) pm, β = 110.74(4)° and Z = 4. The crystal structure has been determined by X-ray diffraction and refined to an R-value of 0.052. The results show that the compound exists as a chain structure of [—®S(C 6 H 4 NO 2 )— Hg— Hg—] n with nitrate ions connecting the chains.

The radical anion of dimesityltetraketone (E Red, I = -0.40 V) is easily generated in THF by potassium mirror/[2.2.2]-cryptand reduction. Its contact ion pairs with Na ⊕ , Cs ⊕ and Ba ⊕⊕ counter cations, prepared in THF solution by single electron transfer from the respective metals, are characterized by their ESR/ENDOR spectra, which exhibit temperature-dependent metal couplings of a Na ⊕ = 0.061 mT (190 K), a Cs ⊕ = 0.021 mT (190 K), and a Ba ⊕⊕ = 0.145 mT (295 K).

Trimethylaluminum adds to cyclotrimeric zirconocene oxide [Cp 2 ZrO]3 to give the cyclodimeric mixed metal complex [Cp 2 Zr(CH 3 )OAl(CH 3 ) 2 ] 2 (3a-dimer) featuring a central Al 2 O 2 containing four-membered ring system. Complex 3a-dimer crystallizes in space group P2 1 /c with cell parameters a = 8.3974(8), b = 8.6509(7), c = 19.718(1) Å, β = 97.36(1)°, Ζ = 2, R = 0.029, R w = 0.038. With methylalumoxane 3a-dimer gives an active catalyst (Zr: Al ≈1:8) for ethylene polymerization.

[OsCl 4 (CH 3 CN) 2 ] · 1/2CH 3 CN has been prepared by the reaction of OsCl 5 with acetonitrile in a slow reaction at room temperature, forming red, moisture sensitive crystals. The compound was characterized by IR spectroscopy as well as by an X-ray structure determination. Space group Pnma, Z = 4, 1281 observed unique reflexions, R = 0.031. Lattice dimensions at 20 °C: a = 1032.5(5), b = 1356.0(7), c = 975.9(5) pm. The complex has a molecular structure, in which the osmium atom is octahedrally coordinated by four chlorine atoms and by two N-atoms of the ciscoordinated acetonitrile molecules. The included CH 3 CN molecules are disordered in two positions.

The title compound 3 was prepared by pyrolysis of the corresponding bis-sulfone 2 and subjected to X-ray structural analysis; space group P 1̅, a = 477.0(1), b = 625.6(2), c = 1363.6(3) pm, α = 82.79(2), β = 83.43(2), γ = 78.18(3)°, Ζ = 1, R = 0.058 for 900 reflections. The molecule contains a crystallographic symmetry centre, thus confirming the anti configuration.

Ethylenedioxybenzotetrathiafulvalene (EDOBTTF), ethylenedioxypyridino[4,5-b]tetrathiafulvalene (EDOP[4,5-b]TTF), ethylenedioxymethylenedithiotetrathiafulvalene (EDOMDTTTF), ethylenedioxyvinylenedithiotetrathiafulvalene (EDOVDTTTF), and ethylenedioxomethylenediselenotetrathiafulvalene (EDOMDSTTF) have been prepared and characterized analytically and spectroscopically.