Volume 46, Issue 5

The dimethylhalonium salts (CH 3 ) 2 X + A- (X = Cl, Br, I; A - = AsF 6 -, SbF 6 - , Sb 2 F 11 - ) are synthesized by methylation of the corresponding methylhalides CH 3 X or dihalomethanes CH 2 Cl 2 and CH 2 Br 2 in the system SO 2 /CH 3 F/MF 5 . The analogous reaction of CH 2 I 2 results in the formation of dimethylmethylendiiodonium hexafluorometallates CH 3 ICH 2 ICH 3 2+ (MF 6 - ) 2 (M = As, Sb). The salts are characterized by Raman-, IR- and NMR-spectroscopy.

The isotypic ternary compounds Ba 3 [MoN 4 ] and Ba 3 [WN 4 ] were prepared by reaction of the transition metals with barium (Ba 3 N 2 , resp.) under nitrogen. The crystal structures were determined by single crystal X-ray diffraction: Ba 3 [MoN 4 ] (Ba 3 [WN 4 ]): Pbca; Z = 8; a = 1083.9(3) pm (1091.8(3) pm), b = 1030.3(3) pm (1037.5(3) pm), c = 1202.9(3) pm (1209.2(4) pm). The structures contain isolated tetrahedral anions [MN 4 ] 6- (M = Mo, W) which are arranged in form of slightly distorted hexagonal layers and which are stacked along [010] with the sequence (···AB···). Two of the three Ba atoms are situated between, the third one is placed within the layers of [MN 4 ]-groups. In this way the structures can be derived from the Na 3 As structure type.

A series of ligand-bridged dinuclear complexes [MM′Cl(µ-Cl)(µ-C 5 H 4 PR 2 ) 2 (CO) 3 ] (M = Ti, Zr, M′ = Cr, Mo, W, R = C 6 H 5 , 4-C 6 H 4 CH 3 ) was synthesized from the mononuclear precursors MCl 2 (C 5 H 4 PR 2 )2 and M′(CO) 3 L 3 . Donor ligands L cleave the chloro bridge either reversibly (L = acetonitrile) or irreversibly (L = CO, P(OMe) 3 ) with formation of the adducts [MM′Cl 2 (μ-C 5 H 4 PR 2 ) 2 (CO) 3 L]. At titanium a terminal Cl - ligand can be replaced by t BuO - whereas MeS - substitutes both terminal and bridging Cl - . The dinuclear complexes [MM′(SMe)(µ-SMe)(µ-C 5 H 4 PR 2 ) 2 (CO) 3 ] thus formed are inert towards CO or P(OMe) 3 .

B 2 H 6 has been shown to react with H 2 S 2 , H 2 S 3 or crude sulphane oil in toluene to form selectively 1,2,4,3,5-trithiadiborolane. The reaction of crude sulphane has been utilized to achieve a convenient synthesis of toluene solutions of H 2 B 2 S 3 which are stable on standing at 0 °C. A mechanism for the sulphur chain degradation in polysulphanes is proposed. Monohydroboration of alkynes proceeds by cis addition from the less hindered side of the triple bond. Both hydrogen atoms of H 2 B 2 S 3 react with 1- or 2-alkynes thus leading to 3,5-dialkenyl-1,2,4,3,5-trithiadiborolane derivatives, respectively.

Reaction of (tBu) 2 Si(OH) 2 with TiCl 4 , TiBr 4 , TiI 4 , and ZrCl 4 affords eight-membered rings 2a-2d. The X-ray structural analysis of 2a, 2b and 2d reveals in 2a and 2b tetrahedral and in 2d octahedral coordination at the transition metal atoms. The octahedral geometry in 2d is due to two additional coordinated solvent molecules. The Ti—O bond lengths in 2a and 2b are short indicating multiple bonding. Compounds 2a-2d are thermodynamically very stable having melting points above 250 °C.

Attempts to prepare selenotellurates with coordination numbers greater than three for the tellurium atom led to the title compounds [K(222-crypt)] 2 TeSe 10 and [Ba(222-crypt)(en)]TeSe 10 ·en 0.5 with a new mixed polychalcogenide anion TeSe 10 2- . The crystal structures of both compounds contain four-coordinate tellurium with two bidentate Se 5 forming a spirocyclic arrangement with Te as the common spiro atom in a planar, almost square coordination. The potassium cation is cryptated by the macro-bicyclic aminopolyether 222-crypt (CN 8), whereas the barium cation is coordinated by the cryptand and a further solvate molecule of ethylenediamine, resulting in a total coordination number of 10. [K(222-crypt)] 2 TeSe 10 : PI, a = 1333.3(6) pm, b = 1214.6(6) pm, c = 1078.3(4) pm, α = 95.80(6)°, β = 90.18(6)°, γ = 115.20(6)°, R = 0.073; [Ba(222-crypt)(en)]TeSe 10 · en 0.5 : PĪ, a = 1802.2(6) pm, b = 1132.1(4) pm, c = 1049.4(4) pm, α = 79.80(6)°, β = 87.27(6)°, γ = 84.63(6)°, R = 0.076.

Normal coordinate analyses for the 24 mixed halogenohexaborates B 6 X n Y 6-n 2- , n = 1—5, Χ ≠ Y = Cl, Br, I, including the pairs of geometric isomers for n = 2, 3, 4 have been performed, based on a general valence force field. Using the bond lengths and force constants for the homoleptic species B 6 X 6 2- , which with respect to the B 6 cage are weighted standardized, the calculated frequencies are in good agreement with observed IR and Raman bands. The boronhalogen stretching vibrations for symmetric molecular axes correspond with the Ra(IR) bands of the homoleptic compounds: ClB 6 Cl 327 (515), BrB 6 Br 207 (430), IB 6 I 152 (394) cm -1 . As a characteristic feature the mixed halogeno clusters exhibit bands with nearly averaged frequencies from asymmetrical axes: ClB 6 Br 261 (487), ClB 6 I 227 (473), BrB 6 I 178 (409) cm -1 . This complete vibrational coupling is confirmed by properly balanced potential energy distribution on BX and BY bonds. There is a slight influence of the different substituents on the internal modes of the B 6 cage (pseudo-O h ), observed in the sequence A 1g >T 1u > E g >T 2g in the region 1220-740 cm -1 . The bands are shifted about 100 cm -1 with increasing mass of halogen, broadened by boron isotopomers (max. 60 cm -1 ), and degenerate vibrations are split by lowered point and site symmetry up to 100 cm -1 .

Si(OMe) 4 reacts with two equivalents of 1,2-(OH) 2 C 6 H 4 in toluene at elevated temperature (70 °C) to yield a colorless microcrystalline product, which we believe to be Si(O 2 C 6 H 4 ) 2 (MeOH) x (x = 1-2). [K(18-crown-6)][Si(O 2 C 6 H 4 ) 2 F] has been prepared by the reaction of Si(O 2 C 6 H 4 ) 2 (MeOH) x with KF and 18-crown-6 in THF and subsequent recrystallization from CH 2 Cl 2 /toluene. The title compound crystallizes orthorhombically in the space group P2 1 2 1 2 1 (No. 19) with a = 10.373(1), b = 18.954(2), c = 13.993(2) Å and Z = 4. The structure was refined to a final R-value of 0.057 for 2037 reflections. The crystal structure shows the presence of close contact ion pairs [d(K –O) = 2.897(7), 2.806(8) A]. The influence of these interactions on the environment of the silicon atom is discussed and the structure of the anion compared with that of the free anion in NEt 4 [Si(O 2 C 6 H 4 ) 2 F].

The syntheses of bis(aluminum)ethane compounds – bis(dichloroaluminum)ethanes to chlorine free bis(diethylaluminum)ethanes 1-10 are described. The connecting ethylene between the two aluminum atoms is identified either as C 2 H 4 (1,2–) or as CH(CH 3 ) (1,1–). The syntheses of Cl 2 AlEt, ethylaluminumsesquichloride and Et 2 AlCl from aluminum, ethylene and AlCl 3 or EtAlCl 2 via bis(aluminum)ethane compounds under various conditions are presented.

The reaction of KSi with [CpFe(CO) 2 ] 2 in DME (1,2-dimethoxyethane) yields deep red crystalline K[CpFe(CO) 2 ] (1). 1 crystallizes monoclinically in the space group P2 1 /a (No. 14) with a = 10.953(4), b = 10.159(3), c = 7.347(2) Å, β = 107.89(2)°, Ζ = 4, R = 0.028, R w = 0.030. Crystals of 1 consist of polymeric chains, formed by strong K-O interactions [d(K-O) 2.915(2), 2.773(2) A], while van-der-Waals interaction between neighboring helices leads to formation of a three-dimensional network with short distances d(K-C) [3.173(3) to 3.292(3) A].

Sulfur-diimides react with bismethylmercapto-pentafluorophenylboranes by reductive 1,3-cycloaddition of the NSN-sequence and formation of the 1,2,4,3-thiadiazaboretidines 2a,b. NMR ( 1 H, 11 B, 13 C, 19 F, 29 Si), mass spectra and the results of the X-ray structure analysis of 2 a are reported and discussed.

(Se 4 ) 2 (Sb 4 F 17 )(SbF 6 ) 3 is formed by reaction of selenium with a large excess of SbF 5 in SO 2 at 363 K. It crystallizes in the monoclinic space group P2 1 / n (Nr. 14) with a = 1124.1(2), b = 1342.7(2), c = 1151.2(3) pm; β = 93.10(2)° and Z = 2. Two crystallographically independent Se 4 2+ units exhibit slight differences of bond distances and angles as well as different numbers of cation-anion interactions. Three regular SbF 6 - octahedra and the mixed valent Sb 4 F 17 - anion, observed previously in only one case, are present.

A “one-pot” reaction involving cobalt(II) nitrate hexahydrate, iodine, tetramethylammonium iodide and ethanedial dioxime (or glyoxime, GH 2 ) in water/methanol solution has afforded the novel double salt, bis(tetramethylammonium) triiodide trans-diiodobis(ethanedial dioximato)cobaltate(III), (N(CH 3 ) 4 ) 2 I 3 (CoI 2 (GH) 2 ). The structure of the salt was determined from single crystal X-ray diffraction data. Crystal data: orthorhombic space group Pnma; C 12 H 30 CoI 5 N 6 O 4 , M r = 1015.84; a = 10.60(1), b = 12.531(5), c = 21.47(2) Å; V = 2851.83 Å 3 ; Z = 4; D c = 2.36 Mg m -3 . The structure consists of three distinctive molecular species, namely, (N(CH 3 ) 4 )+, I 3 - , and (CoI 2 (GH) 2 ) - . The cobaloximatic anion contains Co III in the usual (4+2) octahedral ligand field of four chelating N atoms lying within the molecular equatorial plane, and two iodides occupying the apical positions. The atomic triads, I -Co-I and I- I - I, are slightly bent by an angle of 177.3° and 176.8°, respectively. Two symmetrical O-H-O bridges with slightly diverging O · · · O separations (2.492 and 2.516 A) are effective within the cobaloximatic anion. Van der Waals type intermolecular interactions occur only between the I atoms of adjacent I 3 - and ICol units. These interactions give rise to the formation of “stripes” that propagate throughout the structure, parallel to the crystallographic ac plane. There are no interactions amongst ICol triads in this material.

The phenyliodoantimonates(III) [Et 4 N][Ph 2 SbI 2 ] (1), [Et 4 N] 2 [Ph 2 Sb 2 I 6 ] (2) and [Hpy] 3 [Ph 2 Sb 2 I 7 ] (3) have been prepared and their structures established by X-ray structural analysis. The anion [Ph 2 SbI 2 ]⁻ displays a ψ-trigonal bipyramidal structure with axial Sb–I distances of 2.925(1) and 3.109(1) A. In the dimeric anions [Ph 2 Sb 2 I 6 ] 2- and [Ph 2 Sb 2 I 7 ] 3- the antimony atoms exhibit ψ-octahedral geometries. As observed for [Ph 2 SbI 2 ]⁻, terminal Sb–I bonds in trans-position to one another display significantly different lengths. The anion [Ph 2 Sb 2 I 7 ] 3- displays C i- symmetry with a bridging iodine atom at the crystallographic centre of symmetry. Long Sb—I distances of 3.404(1) A are observed to this atom. A structural correlation of opposite Sb–X distances (X = Cl, Br, I) in linear three centre X–Sb ··· X interactions is presented. The sum of the bond valences in iodoantimonates(III) is a minimum for symmetrical I–Sb–I three centre bonds, reflecting thereby the antibonding influence of the Sb 5 s-orbital. This influence is considerably smaller for bromoantimonates(III) and may be effectively neglected for chloroantimonates(III).

By reacting PhAsCl 2 with NaC 5 H 5 in toluene under low temperature conditions PhAs(h 1 -C 5 H 5 ) 2 was obtained. Metallation of PhAs(h 1 -C 5 H 5 ) 2 with n-BuLi followed by reaction with TiCl 4 led to the As-bridged [1]titanocenophane. The structure and conformation of this air-stable compound are discussed in the light of its 1 H NMR spectrum.

The [1]vanadocenophanes Me 2 E(C 5 H 4 ) 2 VCl 2 (1c) (E = Si, Ge) have been prepared by the metallation of the bis(cyclopentadienyl) compounds Me 2 E(h 1 -C 5 H 5 ) 2 (1a) with butyllithium and subsequent reaction with vanadium(IV) chloride. The complexes lc react with an excess of (NH 4 ) 2 S 5 to give Me 2 E(C 5 H 4 ) 2 VS 5 (1d), the first pentasulfide chelate with a bridged vanadocene system.

FeCr 2 O 4 has been prepared under CO-CO 2 -atmosphere with oxygen partial pressures between 10 -18 and 10 -8 bar. X-Ray and Mößbauer investigations show that under higher pressures FeCr 2 O 4 is not stoichiometric but contains Fe(III), and that corund type Cr 2 O 3 as an additional phase has been formed. In the wide pressure range from 10 -17 to 10 -14 bar the contents of Fe(III) are lower than 1% of total iron, and the corund phase is negligible.

Using a PPP(SCF)—CI calculation, the structure of the butane-2,3-dionemonoxime ligand has been determined. Via SCF—MO calculations, the ionization potential, the electron affinity, the charge densities in the three states (a molecule, a cation and an anion), the SCF-HO-MO’s and the SCF-LUMO’s were calculated in addition to the molecular dipole moment. A new technetium(V) oxocomplex with butane-2,3-dionemonoxime ligand CH 3 COCNOHCH 3 (diacetylmonoxime) has been synthesized and characterized. The complex formation was performed in an alkaline mixture of water and ethanol by reduction of pertechnetate with NaBH 4 in the presence of the monoxime ligand. Infrared, UV-visible spectra, electrophoresis and HPLC data of the resulting complex are reported and discussed.

The pentadentate thioether thiolate ligand ′bu S 5 ′ 2 (= dianion of 2,2′-bis(2-mercapto-3,5-di-tertiary-butylphenylthio)diethylsulfide) reacts with iron(II) ions to give the diamagnetic [Fe′ bu S 5 ′] (1), which only coordinates σ-π ligands such as CO, NO, NO + or P(OPh) 3 . In this respect, the [Fe′ bu S 5 ′] fragment differs from the parent complex [Fe′S 5 ′] (′S 5 ′ 2 - = dianion of 2,2′-bis(2-mercaptophenylthio)diethylsulfide) as well as from the related [Fe′N H S 4 ′] (′N H S 4 ′ 2- = dianion of 2,2′-bis(2-mercaptophenylthio)diethylamine), both of which are able to coordinate also σ-ligands such as N,H 4 or NH 3 . Synthesis of [Fe(CO)′ bu S 5 ′] (2), yields two stereoisomers that can be easily separated owing to their different solubility.

18 and 19 electron NO complexes with the [Fe' bu S 5 '] moiety (' bu S 5 ' 2- = dianion of 2,2′-bis-(2-mercapto-3,5-di-tertiary-butylphenylthio)diethylsulfide) have been isolated and converted reversibly into each other. The unpaired electron in meso-[Fe(NO) ′bu S 5 '], meso-1, is delocalized over the whole molecule and occupies an orbital that is antibonding with respect to Fe– N and Fe–S bonds. Consequently, the NO ligand is readily substituted under mild conditions. In contrast, the 18 electron complex meso-[Fe(NO)' bu S 5 ']PF 6 , meso-2, is entirely inert towards substitution. To our knowledge the exchange of NO by CO in meso-1 via meso-2 is the first example, in which NO is displaced by CO in an isolable NO complex. The NO release from meso-1 via meso-2 can be considered a model for reversible NO bonding in sulfur coordinated metal centres of nitrogenase. It is shown that one-electron redox reactions make stable Fe–NO bonds labile, and the reversible coordination and decoordination of NO in nitrogenase may be induced by a similar process.

A series of disubstituted trans-Fe(CO) 3 L 2 complexes (L = phosphine or phosphite) have been characterized by infrared, 57 Fe Mössbauer, and 31 P NMR spectroscopy. The triple-bond nature of the carbonyl ligands of trans-Fe(CO) 3 L 2 is strengthened with increasing ironto-phosphorus π back-donation. A linear correlation between the isomer shifts and the quadrupole splittings has demonstrated that the phosphorus-to-iron σ donation is offset by the iron-to-phosphorus π back-donation. The linear dependence of the coordination shifts on the isomer shifts has revealed that the iron-to-phosphorus π back-donation plays an important role in the Fe– P bond. There exists a strong interaction between trans phosphorus ligands through the d π orbitals associated with the P–Fe–P bond.

Two 1:1 mixed ligand complexes of copper(II) azide with substituted quinoline and pyridine, namely catena di-μ(1,1)-azido-(4-methylquinoline)copper(II) (1) and catena di-μ(1,3)-azido-[di-μ(1,1)-azido-bis(2-methylpyridine)dicopper(II)] (2) have been prepared and characterized by X-ray crystallography. Crystal data: 1, C 10 H 9 N 7 Cu, space group P2 1 /c, a = 577.8(2), b = 2202.3(5), c = 919.9(2) pm, β = 93.92(2)°, Ζ = 4, and R = 0.035 for 1293 observed MoKa data; 2, C 6 H 7 N 7 Cu, space group P2 1 /a, a = 823.7(2), b = 1303.8(4), c = 895.3(3) pm, β = 112.23(2)°, Ζ = 4, and R = 0.022 for 2133 observed ΜοΚα diffractometer data. In the structure of 1, the Cu(II) has a strongly distorted trigonal bypyramidal coordination, where both azido groups function as μ(1,1) bridging ligands resulting in a columnar structure along the a axis. The polymeric complex 2 has a less distorted square pyramidal structure; one half of the azide groups act as μ(1,1) bridging ligands to form centrosymmetric dimers. These dimeric units are further connected by the remaining μ(1,3) bridging azido groups to form layers within the ab-plane. Infrared and electronic spectral data are also presented and discussed.

The distribution of alkali ions between an aqueous and an organic phase (CH 2 Cl 2 ) in the presence of the cyclic silicic acid esters [OSi(OR) 2 ] n (n = 3,4, R = CH 3 , Si(CH 3 ) 3 ) was determined. The silicic acid esters are about as effective as crown ethers in their extracting power.

[{Cp(Ph 3 P)Ni}SnCl 3 ] reacts with (Me 3 Si) 2 Se in toluene as solvent to form the compound [Cp 4 (Ph 3 P) 3 Ni 5 Sn 6 Se 9 ] (4). The structure of 4 was determined by X-ray diffraction. 4 contains a polycyclic Sn 6 Se 9 -cage which encloses a central CpNi 2 unit.

A new compound LiCo 6 P 4 could be synthesized, it crystallizes in the hexagonal space group P6̅m2 with the lattice constants a = 658.4(3) pm, c = 333.8(2) pm, c/a = 0.507. The structure shows close relations to the Fe 2 P- or Zr 2 Fe 12 P 7 -type structures.