Volume 49, Issue 8

The title compound 1 is an unprecedented example of an 18-crown-6 complex in which coronand rings preserve the conformation of the uncomplexed crystalline polyether. 1 is precipitated, independently of the molar ratio employed, by mixing methanolic solutions of its components at room temperature. The complex crystallizes in the monoclinic system, space group P2 1 /n, with (at -130°C) a = 1771.9(7). b = 833.3(3), c = 2024.2(6) pm, β = 107.13(3)°, V = 2.856(2) nm 3 , Z = 4. D ϰ = 1.325 Mg m -3 . The structure contains infinite chains of alternating host and guest species, in which every HN(SO 2 CH 3 ) 2 guest is linked via C-H ··· O(crown) and C-H ··· O(sulfonyl) interactions with two D 3d -pseudosymmetric crown rings. Within the chain, each D 3d ring acts as an acceptor in six C-H ··· O(crown) and as a donor in four C-H -O(sulfonyl) interactions. Equivalent molecules in the chain are related by v-translation. Pairs of antiparallel chains are connected into ladder-like strands by a sec­ond type of 18-crown-6 molecule that crystallographically preserves the centrosymmetric C′ i conformation of the uncomplexed polyether. These rings accept, via their two symmetry- related pseudocorner oxygen atoms, an N-H ··· O hydrogen bond (H ··· O 210 pm) from one guest molecule in each chain and are also connected to the same guests by a C-H ··· O(sulfonyl) interaction. Parallel strands are linked through C-H- (crown) ··· O(sulfonyl) and C-H(crown) ··· O(crown) interactions to form a three-dimensional network. The H ··· O distances of the strand-building and the strand-connecting C-H ··· O interactions lie in the range 230-260 pm. For comparison, two modifications of the pure guest compound, crystallized from CCl 4 (modification 2a) or CH 2 Cl 2 (modification 2b), were structurally characterized. The crystallographic data (at -95 °C) are for 2a: monoclinic, space group P2 1 /c, a = 767.5(2), b = 974.5(2), c = 915.0(3) pm, β = 105.80(2)°, V = 0.6585(3) nm 3 , Z = 4, D ϰ = 1.747 Mg m -3 ; for 2b: monoclinic, space group P2 1 /c, a = 776.2(3), b = 997.1(3), c = 923.0(4) pm, β = 111.10(3)°, V = 0.6665(4) nm 3 . Z = 4, D ϰ = 1.726 Mg m 3 . In both modifications, the molecules are connected by an N-H ··· O hydrogen bond (H ··· O 234 pm in 2a, 220 pm in 2b) into chains in the z-direction, the principal difference between 2a and 2b arising from the differing conformational character of the acceptor oxygen atoms. Corresponding bond lengths and bond angles in 2a and 2b and in the guest molecule of 1 are essentially identical, as are the torsion angles around the S-N bonds in 2a and 2b. The local C 1 symmetry of the CO 2 SNSO 2 C framework in 2a and 2b changes to an approximate C 2 symmetry upon complexation with 18-crown-6. thus optimizing the host-guest comple­mentarity.

The sodium salt of the most simple polynitro-substituted hydrocarbon anion. Na ⊕⊖ C(NO 2 ) 3 , (for a hazard warning cf. [***]) crystallizes from ether solutions without and with addition of 18-crown-6 either in a polymer band. [(Na ⊕⊖ C(NO 2 )3)dioxane] ∞, or as a solvent- separated ion pair, [(Na ⊕ /18-crown-6)(THF 2 ] ⊕ [(Na ⊕ /18-crown-6)(O 2 N-C ⊖ (NO 2 ) 2 ) 2 ] ⊖ . The Na ⊕ cations are each 8-fold coordinated in hexagonal bipyramidal arrangement. According to extensive quantum-chemical calculations based on the structure coordinates, the formation of these novel salts can be traced back to the charge distribution in the anions ⊖ C(NO 2 ) 3 . which due to negatively charged oxygen centers are favorable complex ligands. The structure determining effects of solvation are discussed.

Crystals of lemon yellow dipotassium nitranilate and of yellow disodium nitranilate di­hydrate have been grown and their structures determined at 290 and 200 K. The six-member- ed, O 2 N-disubstituted rings show a pronounced cyanine distortion with all four CO bonds identical and the two (OCC(NO 2 )CO) ⊖ chains connected by single CC bonds of each 156 pm length. In the anhydrous K ⊕ salt, the ring is planar, but in the Na ⊕ hydrate salt it exhibits a twist conformation. Quantum chemical calculations allow to reproduce the structure in every detail, demonstrate strong charge alternation along the cyanine chains with considerable delocalization into the O 2 N acceptor substituents, and suggest that the rather long connecting CC bonds contain positively charged carbon centers on both ends. In addition, metal ion coordination effects as well as the rather high pK a value of nitranilic acid are rationalized.

Reactions of [2.2.2]cryptand, 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo-[8.8.8]hexacosane, (“cryptand 222”) with cadmium chloride and mercuric chloride yielded crystals of [Cd(cryptand 222)][CdCl 4 ] (1) and [Hg(cryptand 222)][Hg 2 Cl 6 ] (2). 1 crystallizes tetragonally, space group P4 2 /n, Z = 4, a = 1239.8(2), c = 1801.2(8) pm; 2 is monoclinic, space group P2/n, Z = 2, a = 1060.3(3), b = 955.2(2), c = 1607.0(3) pm. and β = 108.85(2)°. In the cations of both complexes the metal ions are enclosed in the bicyclic ligand and show 8-coordination to its six oxygen and two nitrogen atoms, the coordination polyhedron is a distorted cube for 1 and a bicapped trigonal antiprism for 2. The anion of 2 is dimeric, the two mercury atoms are connected via chlorine bridges with Hg-Cl distances of 258 and 278 pm, the Hg-Cl bond lengths to the two terminal chloro ligands being shorter at 236 and 238 pm.

1,2-Di(silyl)benzene (3), has been prepared in a three-step process starting with the reac­tion of 1,2-dibromobenzene and p-tolyl(chloro)silane with magnesium in tetrahydrofuran. which affords 1,2-bis(p-tolylsilyl)benzene (1) as a stable high-yield intermediate. Compound 1 has been converted into 1,2-bis(trifluoromethanesulfonatosilyl)benzene (2) with trifluoro- methanesulfonic acid, and finally into 3 by reduction with lithiumaluminiumhydride, both again in high yields. - In an attempt to prepare 1,2,4,5-tetra(silyl)benzene in an analogous way. only the bis-silylated species could be obtained (from 1,2,4,5-C 6 H 2 Br 4 . p-MeC 6 H 4 SiClH 2 and Mg powder: 1,4-dibromo-2,5-bis(p-tolylsilyl)benzene. 4, and 1,4-dibromo-2,5-di(silyl)- benzene, 6, via 1,4-dibromo-2,5-bis(trifluoromethanesulfonatosilyl)benzene, 5). The crystal structures of compounds 4 and 6 have been determined by X-ray diffraction. The results indicate no steric hindrance in these molecules and it is thus not obvious from the molecular structures why the silylation reaction does not proceed any further to give the tetrasilylated benzene derivatives. Electronic effects have to be invoked to rationalize the experimental findings.

The stable 2,2-diphenyl-1,2-dihydroquinolinenitroxide radicals 1 react with nitric oxide (NO) to form the stable nitro compounds 2 and 3 as main products. The stable dinitro compounds 6 and 1,2-dihydroquinolines 7 are formed in minor yield as side-products accom­panied with the unstable N-nitroso compounds 4 and 5, which further decompose to form the stable products mentioned above. The proposed mechanism of the reaction is discussed in terms of homolytical processes and is supported by PM 3 calculations.

Yellow crystals of [Fe 2 (HPTP)(OH)(NO 3 ) 2 ](Cl0 4 ) 2 (HPTP = N,N,N',N'-tetrakis(2-pyridyl- methyl)-2-hydroxy-1,3-diaminopropane) were grown by slow diffusion of diethylether into a solution of the complex salt in acetonitrile. Crystal data: space group R3̅, a = 4280,1(15) pm, c = 1147,6(7) pm, Z = 18. The complex exhibits a binuclear Fe(III) core with (μ-oxo)(μ-alkoxo) ligands as bridging units. The nitrate anions coordinate each with a short and a long Fe-O bond. The coordination spheres of the iron atoms can be looked at as distorted edge-shearing pentagonal bipyramides. The complex cation was introduced into the interlayer region of montmorillonite by cation exchange in acetonitrile. The results of X-ray, IR- and UV/VIS experiments suggest that the cation exchange is reversible. In the interlayer region the dinuclear cations are arranged in a rather loosely packed way, thus creating channels similar to those in pillared smectites or zeolites, respectively.

Photolysis of hexacarbonyl-chromium(0), -molybdenum(0), and -tungsten(0) in presence of fumaronitrile yields at room temperature pentacarbonyl-fumaronitrile-chromium(0) (1), - molybdenum(0) (2), and -tungsten(0) (3). The complexes were purified by crystallization and characterized by IR and 13 C-NMR spectroscopy. The fumaronitrile ligand is bonded to the M(CO) 5 moiety by one nitrile nitrogen atom rather than by the carbon-carbon double bond. In toluene 2 dissociates into fumaronitrile and pentacarbonyl-molybdenum(0), which is stabi­lized by the solvent. Fumaronitrile and solvated pentacarbonyl-molybdenum(0) exist in solu­tion together with 2 in an equilibrium which lies in favour of the former species.

By the reaction of acetophenone with sulfur and primary amines yellow-coloured crystals of the title compound are formed. It crystallizes in the monoclinic space group P2 1 /n with lattice constants a = 1309.9(2) pm, b = 926.5(2) pm, c = 1582.2(2) pm and β = 114.00(1)°. The structure of the eight-membered heptathiocane ring is characterized by a crown confor­mation. The range of the S-S distances [204.4(1)-207.3(1) pm], the S-S-S bond angles [107.2(1)- 109.0(1)°] and the S-S-S-S torsion angles [93.2(1)-97.7(1)°] is comparable to those observed in α-, β- and γ-sulfur.

Room temperature Mößbauer spectra of ferrimagnetic spinels in the system Cd ϰ 2+ Fe 1-ϰ 3+ [Ni 1-ϰ 2+ Fe 1-ϰ 3+ ]O 4 have been interpreted using the polyhedron model which is based on six different environments at the A-site for the B-site Fe 3+ -ions. To each environment belongs one sextet with a characteristic magnetic splitting. An additional sextet is due to Fe 3+ -ions at the A-site.

MgNi 2 P was prepared by heating a mixture of the elements and investigated by means of single crystal X-ray methods. The compound crystallizes in an ordered Fe 3 C-type structure (Pnma; a = 6.477(1) Å, b = 6.364(1) Å, c = 5.001(1) Å; Z = 4). Ni and P atoms are linked together to a three-dimensional framework with octogonal tubes running along [010], which are occupied by Mg atoms in the form of stretched zigzag chains.

Two modifications of ThNi 2 P 2 were prepared in a tin flux at 850 °C (α-ThNi 2 P 2 ) and 1000 °C (β-ThNi 2 P 2 ). The crystal structures of both modifications were refined from single­crystal X-ray data. α-ThNi 2 P 2 (BaCu 2 S 2 type structure): Pnma. a = 819.69(5), b = 394.28(3), c = 981.54(7) pm. R = 0.028 for 32 variables and 654 structure factors: β-ThNi 2 P 2 (CaBe 2 Ge 2 type structure): P4/nmm, a = 408.5(1), c = 908.0(3) pm, R = 0.033 for 15 variable parameters and 261 F values. Although the two structures are closely related, they can be transformed into each other only by a reconstructive phase transformation. The differences and similari­ties of the two structures are discussed. The high temperature form has higher symmetry, a smaller number of variable positional parameters, and a tendency for higher coordination numbers.

The title compounds were prepared by arc-melting of the elemental components and sub­sequent annealing. Their crystal structure is hexagonal P 6̅ 2 m with one formula unit per cell. It was determined from single-crystal X-ray data of La 12 Re 5 C 15 (a =1116.8(1) pm, c =545.3(1) pm, R = 0.060 for 287 structure factors and 27 variable parameters) and Ho 12 Re 5 C 15 (ia = 1066.7(1) pm, c = 504.2(1) pm, R = 0.018 for 392 F's and 31 variables). The structures correspond to the formula Ln 12 [ReC 3 ]2[Re 3 C 3 (C 2 ) 3 ],where the brackets indicate two differ­ent trigonal planar anionic rhenium-carbon groups. The coordination of the rhenium atoms in these polyanions seems to be compatible with the 18-electron rule.

A synthetic procedure is described for the preparation of the tetradentate N 2 O 2 ligands H 2 [H 4 ]L 1 =6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methyl- phenyl)heptane, H 2 [H 2 ]L 1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methylphenyl)-1-heptene, and H 2 L 1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2- hydroxy-3-t-butyl-5-methylphenyl)-1,5-heptadiene, which are asymmetric derivatives of the ligands tetrahydrosalen, dihydrosalen, and salen. Complexes Ni[H 4 ]L 1 , Ni[H 2 ]L 1 , NiL 1 , CoL 1 , Ni[H 4 ]L 2 (([H 4 ]L 2 ) 2- = anion of H 2 [H 4 ]L 2 = N,N'-bis(2-hydroxy-3-t-butyl-5-methylbenzyl)- trans-(S,S)-1,2-diaminocyclohexane), and NiL 2 were prepared, characterized (VIS and IR ab­sorption, magnetic moment) and subjected to spectrophotometric titration with pyridine, to determine the equilibrium constants for adduct formation. Single crystal X-ray structure analy­ses were carried out for Ni[H 2 ]L 1 (monoclinic, P2 1 /n; a = 8.926(4), b = 29.324(7), c = 8.411(4) Å; β = 95.3(1)°; Z = 4), CoL 1 (monoclinic, C2/c; a = 25.389(2), b = 18.139(2), c = 10.179(1) Å; β = 112.227(6); Z = 8), and Ni[H 4 ]L 2· acetone (tetragonal, P4 1 2 1 2; a = 13.928(3), c = 33.698(5) Å; Z = 8). In all of the three complexes, the N 2 O 2 -metal coordination core is square-planar. The skeleton of the tetradentate ligand is more or less twisted. The planar cobalt(II) complex CoL 1 is a low spin d 7 system with μ exp = 2.02 BM at 298 K, whereas the planar complexes NiL 1 , Ni[H 2 ]L 1 and Ni[H 4 ]L 2 are diamagnetic (μ exp = 0.28-0.64 BM). The blue solvate Ni[H 4 ]L 1 - 3EtOH · H 2 O is paramagnetic (μ exp = 3.04 BM), which points to octahedral coordination. In aerated acetone solution, the tetrahydrosalen-type complex Ni[H 4 ]L 1 activates dioxygen and one C-N bond is oxidatively dehydrogenated. The VIS spectrum of the dihydrosalen-type complex formed is virtually identical with that of the aldimine complex Ni[H 2 ]L 1 . In the pres­ence of dioxygen, Co[H 4 ]L 1 and Co[H 2 ]L 1 are readily oxidized to CoL 1 in acetone solution.

The reactions of Vi 2 (Me)SiCl or Vi 3 SiCl with t BuLi in pentane solution at low temperatures (-78 to 20 °C) are governed by the addition of t BuLi to one of the vinyl groups, followed by LiCl elimination to yield the silaethenes Vi(Me)Si=CHNp (1) and Vi 2 Si=CHNp (2), re­spectively. The following reactions of 1 and 2 without or with trapping reagents have been studied in some detail. Both silaethenes undergo dimerization with formation of 1,3-disilacyclobutane derivatives, in case of 2 accompanied by trimers. A surprise is the generation of the disilanes Vi(Me)Si(CH=CH t Bu)Si(Me)Vi(CH 2 CH 2 t Bu) (3) and Vi 2 Si(CH=CH t Bu)SiVi 2 (CH 2 CH 2 t Bu) (17) very probably by intermolecular ene-type reac­tions. With DMB or isoprene as trapping agents [4 + 2]-cycloadducts 11, 14, 15, 21, ene-pro- ducts 10, 13 and substitution products 12, 22 are obtained. A very efficient indirect detection of 1 and 2 has been achieved with Me 3 SiOMe as quenching reagent, which gives excellent yields of the adducts Vi(Me)Si(OMe)CH(SiMe 3 )Np (16, 91%) and Vi 2 Si(OMe)CH(SiMe 3 )Np (23, 76%). respectively. Problems in the characterization of iso­mer mixtures arise from difficulties in the GC separation procedure and from the limited thermal stabilities of some of the products. 1 and 2 are very similar with respect to the reactivity of the Si=C double bond, but differ considerably in their tendency to undergo polymerization which is connected to the number of vinyl groups. Therefore, the yields of the typical Si=C products is drastically reduced in the case of 2. In spite of separation pro­blems most of the products have been characterized by a combination of GC/MS. GC/FT-IR and NMR measurements.

By reaction of [B 6 H 6 ] 2- with diiodopropane or diiodobutane in dichloromethane the 1,2- rimethylene-pentahydro-closo-hexaborate(1-), cis-[B 6 H 5 (CH 2 ) 3 ] - , and the 1,2-tetra-methylene- entahydro-closo-hexaborate(1-), dv-[B 6 H5(CH 2 ) 4 ] - are obtained, respectively. The compounds were separated from excess [B 6 H 6 ] 2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of [P(C 6 H 5 )4][B 6 H 5 (CH 2 )3] (I) and [P(C 6 H 5 )4][B 6 H 3 (CH 2 )4] (II) have been determined by single crystal X-ray diffraction analy­sis: I is triclinic, space group P1̅ with a = 7,388(2), b = 12,254(2), c = 14,415(2) Å, α = 85,638(12)°, β= 84,06(2)°, γ = 85,13(2)°; II is monoclinic, space group P2 1 /c with a =9,7855(10), b = 11,0793(10), c = 25,2386(10) Å, β= 2,491(10)°. The 11 B NMR spectra of oth compounds reveal the feature of a cis-disubstituted octahedral B 6 cage. The 13 C NMR pectrum of I exhibits a quartet at 15,46 ppm with 1 J(C,B) = 121,7 Hz (B-CH 2 ) and a triplet at 37,98 ppm with 1 J(C,H) = 124,4 Hz (CH 2 ). For II a quartet at 12,89 ppm with 1 J(C,B) = 105,5 Hz (B-CH 2 ) and a triplet at 30,00 ppm with 1 J(C,H) = 124,4 Hz (CH 2 ) are observed. In the 1 H NMR spectrum of I two multiplets at 0,73 and 1,90 ppm of the CH 2 groups and two singlets at 2,23 and -3,71 ppm of the BH fragments are bserved; the signals of the CH 2 groups of II are at 0,60 and 1,35 ppm and of the BH fragments at 2,15 and -4,81pm,respectively. The IR and Raman spectra exhibit five very strong CH stretching bands between 2807 and 2938 cm -1 in case of I and between 2817 and 2889 cm 1 in case of II.

Single crystals of the title compound have been obtained by neutralization of formic acid with solid rubidium carbonate and subsequent solvent evaporation at room temperature. The very hygroscopic crystals are orthorhombic, space group Pbca (Nr. 61), with a = 7.614(1), b = 17.926(2), c = 7.862(1) Å and Z = 8. The structure, which has been refined to R = 0.072 and R w = 0.067 for 1008 unique reflections, is isotypic with that of the analogous potassium compound. It comprises layers of edge-sharing distorted RbO 8 square antiprisms, sandwiched between two adjacent formate layers. The sandwiches are hold together by O···H···O inter­actions, which are, however, rather weak.

V0 2+ forms complexes of composition VO(L 1 )EtOH), VO(HL 1 ) 2 and VO(HL 2 )(H 2 O) with the ithium or sodium salts of 6-droxymethyl-pyridine-2-arboxylic acid (H 2 L 1 ) and 4,8-hydroxyquinoline-2-carboxylic acid (H 3 L 2 ). VCl 2 (salen/salphen) and VCl 2 (napgly/ nappa) (napgly and nappa are the Schiff bases derived from o-ydroxynaphthaldehyde and glycine or phenylalanine, respectively), prepared from the oxo precursor and SOCl 2 , react with Li 2 L 1 and the lithium salts of benzilic acid (H 2 L 3 ) and ortho-ydroxybenzoic acid (H 2 L 4 ) to yield the non-oxo (“bare”) complexes V(salen)L 1 , V(salen)L 3 , V(salphen)L 3 , V(salen)L 4 , V(napgly)L 1 , V(nappa)L 1 , and V(nappa)L 4 . The complexes have been characterized by IR, EPR and elemental analyses. VOCl 2 (salen) crystallizes in the monoclinic space group Cc, a = 14.579(3), b = 9.537(2), c = 13.453(3) Å, β=120.92(3)°. The molecule exhibits gross distor­tions from octahedral geometry. An improved synthesis for H 2 L 1 is described.

Single crystals of KCU 5 V 3 O 13 were prepared by recrystallization from flux. The black crystals show triclinic symmetry, space group C i 1 -P1̅, a = 6.0858, b = 8.2605, c = 10.6937 Å, α = 97.815, β = 92.317, γ = 90.477°, Z = 2. KCu 5 V 3 O 13 is strongly related to KMgCu 4 V 3 O 13 , showing VO 4 tetrahedra, trigonal bipyramids and stretched square pyramids around Cu 2+ . K + is surrounded by ten oxygen. The crystal structure is discussed with respect to other magnesium containing copper vanadium oxides.

Single crystals of KBa 2 V 2 O 7 Cl were prepared by crystallization from flux. The transparent crystals crystallize with hexagonal symmetry, space group D 4 6h -P6 3 /mmc, a = 5.7688, c = 15.0762 Å. Z = 2. KBa 2 V 2 O 7 Cl is characterized by V 2 O 7 double tetrahedra and a statistical distribution of K + and Ba 2+ surrounded by nine O 2- and one Cl - . One point position occu­pied by Ba 2+ shows a 3 + 6 + 3 anti-cuboctahedral coordination. KBa 2 V 2 O 7 Cl is isotypic to K 3 Mo 2 O 7 Br.

Single crystals of Cu 0.25 Ho 1.25 W 2 O 8 were prepared by recrystallization from melts and investigated by X-ray diffractometer technique. Cu 0.25 Ho 1.25 W 2 O 8 crystallizes with mono­clinic symmetry, space group C2/c, a = 19.123, b = 5.613, c = 11.479 Å, β = 111.44°. Z = 8. It represents a new structure type characterized by W 4 O 18 groups and Cu + /Ho 3+ at one point position in statistical distribution. Cu + /Ho 3+ show an octahedral coordination. Another point position is occupied by Ho 3+ with C. N. = 7.

Treating a derivative of (-)-camphorsulfonimide (CA name: (3aS)-8,8-dimethyl-4,5,6,7- tetrahydro-3H-3a.6-methano-2,1-benzisothiazole 2,2-dioxide) or the isomeric (+)-fenchonesulfonimide with nitronium tetrafluoroborate in acetonitrile does not lead to the expected products of cationic reactions, e.g. of the Ritter reaction for halogenated compounds, but provokes a cleavage of the sulfonimide group with the formation of a ring-opened product containing a sulfonyl fluoride and a nitroimine group. The reaction does occur only in the presence of solid nitronium tetrafluoroborate. but not after prior dissolution of the reagent. An X-ray structure of the product from (1 S)-3-endo-bromocamphorsulfonimide confirms this unusual reaction.