Volume 57, Issue 5

The crystal structure of bis(η 4 -1,3-cyclohexadiene)monocarbonyliron has been redetermined by X-ray data. The compound crystallizes in the enantiomorphic, orthorhombic space group P2 1 2 1 2 1 with one complete molecule in the asymmetric unit. For concordance to the originally reported structure, which was determined under ambient conditions, the redetermination has been carried out at room temperature and at low temperature (T = 293 K: a = 7.618(2), b = 8.522(2), c = 17.138(4) Å, V = 1112.6(5) Å 3 , R1 = 0.0226, wR2 = 0.0539; T = 120 K: a = 7.509(2), b = 8.417(3), c = 16.778(6) Å, V = 1060.3(6) Å 3 , R1 = 0.0242, wR2 = 0.0533). The redetermination proved this complex to have non-crystallographic C2v point group symmetry. Correlation effects to the atomic coordinates and displacement parameters introduced problems during the structure refinement caused by pseudo-symmetry of the molecule. All bond lengths, angles, and torsion angles appear in this revised crystal structure in the normal range for π-coordinated diene transition metal complexes.

Reaction of various 1,2-dihalodiboranes(4) with Na[(η 5 -C 5 H 4 R)M(CO) 3 ] yielded the diborane(4)yl complexes [X(Me 2 N)B-B(NMe 2 ){ η 5 -(C 5 H 4 R)M(CO) 3 }] (5, X = Cl, R = H, M = Mo; 6, X = Br, R = Me, M = Mo; 7, X = Br, R = H, M = W ;8, X = Br, R = Me, M = W )and [Cl(C 4 H 8 N)B-B(NC 4 H 8 ){ η 5 -(C 5 H 5 )W(CO) 3 }] (9). The reactivity of diborane(4)yl complexes of the type [X(Me 2 N)B-B(NMe 2 ){η 5 -(C 5 H 5 )M(CO) n }] (X = Cl, Br; M(CO) n = Fe(CO) 2 , Mo(CO) 3 ) with respect to substitution of X and CO, respectively, was investigated. The novel derivatives [MeO(Me 2 N)B-B(NMe 2 ){η 5 -(C 5 H 5 )Mo(CO) 3 }] (10), [MeO(Me 2 N)B-B(NMe 2 ){η 5 -(C 5 H 5 )Fe(CO) 2 }] (11), and [Br(Me 2 N)B-B(NMe 2 ){η 5 -(C 5 H 5 )- Mo(CO) 2 (PMe 3 )}] (12) were obtained. All compounds were fully characterised in solution by NMR spectroscopy and by elemental analysis.

New magnesium based intermetallic compounds PrPtMg, NdPtMg and SmPtMg were synthesized from the elements by reaction in sealed tantalum tubes in a high-frequency furnace. The three compounds were investigated by X-ray powder and single crystal diffraction: ZrNiAl type, space group P6̄2m, a = 752.34(8), c = 412.66(4) pm, wR2 = 0.0668, 341 F2 values, 14 variables for PrPtMg, a = 748.80(8), c = 411.52(4) pm, wR2 = 0.0521, 196 F 2 values, 14 variables for NdPtMg and a = 743.90(5), c = 409.80(3) pm, wR2 = 0.0489, 248 F 2 values, 12 variables for SmPtMg. From a geometrical point of view these structures are composed of two types of platinum centered trigonal prisms, i. e. [Pt1Mg 3 RE 6 ] and [Pt 2 Mg 6 RE 3 ]. These prisms are condensed via common edges and faces. Together the platinum and magnesium atoms build three-dimensional [PtMg] networks in which the rare earth atoms are located in distorted pentagonal channels. Magnetic susceptibility data of PrPtMg show Curie-Weiss behaviour with an experimentalmagnetic moment of 3.59(2) μ B and a paramagnetic Curie temperature of 7.5(5) K. Ferromagnetic ordering is detected at T C = 8.0(5) K with a magnetic moment of 1.75(5) μ B /Pr at 4.5 K and 5 T. SmPtMg orders ferromagnetically below 52(1) K with a presumably complex spin structure in the ordered state.

Bis(3,5-di-t-butyl-1,2-benzoquinone 1-oximato)copper(II), Cu(ox) 2 , and its mixed-ligand complexes, Cu(ox)L x [L x = 8-hydroxyquinolinato (L 1 ), N-Phenyl-salicylaldimine (L 2 ), N-phenyl- 3,5-di-t-butylsalicylaldiminato (L 3 ) and N-(2-hydroxyphenyl)-3,5-di-t-butylsalicyl-aldiminato (L 4 )], were prepared and their spectral behavior as well as redox-reactivity towards PPh 3 , (m-ClC 6 H 4 ) 3 P, (m-CH 3 C 6 H 4 ) 3 P and PPh 2 -(CH 2 ) 4 -PPh 2 studied by analytical and spectroscopic (IR, UV-vis, ESR) techniques and magnetic measurements. Cu(ox) 2 and Cu(ox)L 4 complexes prepared in air show μ ef values of 2.84 and 3.33 μ B , respectively, and are consistent with an S= 1 and S= 3/2 ground states. Both compounds are formulated as copper(II)-radical complex exhibiting intramolecular ferromagnetic coupling between the orthogonal d x 2 -y 2 magnetic orbital of the Cu II ion and that of the π-radical ligand.

Piperazinium tetrabromocadmate(II)-monohydrate, [C 4 H 12 N 2 ]CdBr 4 · H 2 O (1) crystallizes with isolated [CdBr 4 ] 2- anions, piperazinium cations, and water molecules (monoclinic, P2 1 /c, Z = 4, a = 698.7(1), b = 1348.6(3), and c = 1432.4(3) pm, β = 92.97(3)˚ at 293 K). The crystal structure of 1 is almost the same as that reported in Inorg. Chim. Acta 187, 141 (1991). The crystal of piperazinium tetraiodocadmate(II), [C 4 H 14 N 2 ]CdI 4 (2) consists of isolated [CdI 4 ] 2- anions and piperazinium cations (orthorhombic,P2 1 2 1 2 1 , Z=4, a = 903.2(5), b = 1226.3(6), and c = 1307.9(7) pm at 293 K). The room temperature phase of bis(trimethylsulphonium) tetrabromocadmate( II), [(CH 3 ) 3 S] 2 CdBr 4 (3) has isolated [CdBr 4 ] 2- anions and trimethylsulphonium cations (orthorhombic, P2 1 2 1 2 1 , Z = 4, a = 911.3(1), b = 1329.2(2), and c = 1454.7(2) pm at 293 K).

The system (1 - x)NiIn 2 S 4 - xNiIn 2 Se 4 has been investigated by X-ray powder methods. The subsolidus phase diagram is constructed in the temperature interval 600 -1000 °C. The spinel type NiIn2S4 exhibits a phase width up to the composition NiIn 2 S 2 Se 2 at 900 °C and NiIn 2 S 2.8 Se 1.2 at 600 °C. A new layered compound is formed for 0.7 ≥ x ≥ 0.5 at 600 °C and for x = 0.6 at 900 °C which crystallizes in the MgAl 2 S 4 -type with a = 392.4 and c = 3739.6 pm (x = 0.6) for the hexagonal cell.

A new strontium lithium titanate with composition SrLi 2 Ti 6 O 14 has been discovered in the ternary system SrO - Li 2 O - TiO 2 . Single crystals of this compound have been grown by the flux method. The structure of SrLi 2 Ti 6 O 14 has been solved using X-ray data (Mo-K α radiation, orthorhombic, space group Cmca, Z = 8, with a = 16.570(5), b = 11.150(2), c = 11.458(2) Å , R1 = 0.039 (wR 2 = 0.087)). The crystal structure is built by edge and corner sharing TiO 6 octahedra which form layers parallel to the (100) plane. Consecutive layers [deduced from a mirror plane parallel to (100)] are linked by common corners in the a direction. Lithium atoms in tetrahedral coordination occupy vacancies of the framework of titanium octahedra, while strontium atoms lie in 11-coordinated sites between two successive layers.

The mixed-ligand dinuclear complexes (2,2'-dipyridyl)-(3-methoxysalicylaldiminato)copper( II) perchlorate (1) and (2,2'-dipyridyl)-(4-methoxysalicylaldiminato)copper(II) perchlorate (2)were synthesized and their crystal structures determined. Both structures consist of a dimeric unit involving a planar Cu 2 O 2 group. In both structures, the coordination sphere of the Cu atoms can be described as an elongated octahedron where the basal plane is formed by the twoN atoms of the 2,2'-dipyridyl molecule and the two O atoms of the salicylaldehyde anion. The phenoxo O atom is the negative ligand of the monomeric unit. Two apical Cu-O contacts complete the 4+2 coordination of the Cu atoms. They correspond to one of the O atoms of the perchlorate anion and to the O atom of the nearest salicylaldehyde molecule. Variable-temperature magnetic susceptibility data obey the Curie-Weiss law with Θ = -10.3(2) K for 1 and -10.1(2) K for 2. The decrease of the effective magnetic moment from 1.89(7) μB at 300 K to 1.77(7) μB at 70 K for 1 and from 1.88(8) μB at 300 K to 1.76(8) μB at 70 K for 2 and the negative Weiss constants indicate weak antiferromagnetic interactions between the two copper atoms in the dimeric units.

In order to study hydrogen bonding networks and packing arrangements in ionic organic crystals, low-temperature X-ray structures were determined for two chemically related onium salts BH + (MeSO 2 ) 2 ND, where BH + is 8-hydroxyquinolinium (1; monoclinic, space group P2 1 / c, Z´ = 1) or 8-aminoquinolinium (2; monoclinic, P2 1 /n, Z´ = 1). The packings are governed by strong hydrogen bonds, π-π stacking interactions and weak hydrogen bonding. In both compounds, hydrogen bonds using the NH/OH donors of the cations and O/N acceptors of the anion result in simple chain polymeric structures, which extend parallel to the y axis and are propagated by translation (1) or 2 1 transformation (2). Moreover, an intramolecular N- H···O hydrogen bond is present in the 8-hydroxyquinolinium cation. As a common feature, the anion substructures are pervaded by hexagonal channels parallel to y, each one accommodating either two separate stacks of translation related cations (1) or a unique (merged) stack of inversion related cations (2). The crystal cohesion is reinforced by numerous weak hydrogen bonds of the types C ar -H···O=S and CH 2 -H···O=S, the latter creating in each structure a topologically different double-chain ribbon of anions. All C-H···O contacts taken into consideration have normalized parameters d(H···O) ≤ 268 pm and θ(CDH···O) ≥ 126°.

In order to study weak hydrogen bonds originating from inductively activated C(sp 3 )-H donor groups, low-temperature X-ray structures are reported for three onium salts of general formula BH + (MeSO 2 ) 2 N-, where BH + is Me 3 N + CH 2 CH 2 OH (1; orthorhombic, space group P2 1 2 1 2 1 , Z′ = 1), Me 3 N + CH 2 C(O)OH (2; orthorhombic, P2 1 2 1 2 1 , Z′ = 1), or Me 2 HN + CH 2 CH 2 NMe 2 (3; monoclinic, P2 1 /c, Z′ = 1). The asymmetric units consist of cationanion pairs assembled by an O-H···O=S hydrogen bond in 1, an O-H···N- bond in 2, and an N + -H ··· N - bond in 3. The packings display a plethora of short interionic C(sp 3 )-H···O/N contacts that are geometrically consistent with weak hydrogen bonding; those taken into consideration have normalized parameters d(H ··· O) ≤ 269 pm, d(H···N) ≤ 257 pm and θ(C-H···O/N) ≥ 127°. The roles of the weak hydrogen bonds are as follows: In structures 1 and 3, the anions are associated into corrugated layers, which intercalate catemers of cations (1) or stacks of discrete cations (3), whereas structure 2 involves cation catemers surrounded by four anion catemers and vice versa; moreover, all cations are linked to adjacent anions by several weak hydrogen bonds (and to one anion in particular by the strong H bond). Among the cation-anion interactions, the N + (CH 2 -H···) 3 O tripod pattern arising in 1 and 2 is of special interest.

Reaction of (L)-3-acetyl-5-benzyl-1-phenyl-4,5,-dihydro-1,2,4-triazine-6-one oxime (1) with copper acetate afforded the complex 5 in high yield. Single crystal X-ray structural analysis of 5 revealed a square-pyramidal geometry around the copper ion where the two oxime ligands are coordinated symmetrically to the Cu atom. The apex of the square-pyramid is occupied by a chloride ligand with the copper atom roofed above the center of the plane of the four coordinating nitrogens by about 0.22 Å . MS-FAB, magnetic and other analytical data are in accord with this solid-state structure.

Two series of the title compounds were prepared by reaction of 1,2-bis(4-amino-5-mercapto- 4H-1,2,4-triazol-3-yl)ethane with N-aryl-2-oxopropane-hydrazonoyl chlorides. The spectral data of such compounds indicated that they exist predominantly in the bis-hydrazone tautomeric form.

A number of new linearly fused furochromones were synthesized. The methodology was performed starting from naturally occurring visnagin and khellin via enaminone formation using N,N-dimethyl formamide dimethylacetal followed by ring closure in acidic medium. Various reactions on the enaminone derivatives are described.

(+)-17-Thionosparteine and its perchlorate have been obtained and characterized by IR and NMR spectroscopy as well as by X-ray diffraction analysis. Introduction of the thiolactam group into the cis-quinolizidine system causes conformational rigidity of this fragment. Moreover, the conformations in solution and in the solid state are the same.

Condensation of α-tocopherol and 2,2,5,7,8-pentamethyl-6-hydroxychroman (the model compound) with peracetylated glucose, mannose and galactose was carried out. The influence of various acidic catalysts on the chemical yield and the stereochemical outcome of the glycosylation was investigated.

Several new 1H-benzo[f]chromene derivatives (3aÐd) were prepared by the reaction of 7-substituted-2-naphthols (1a,b) with substituted α-cyano-4-methoxycinnamonitriles (2a,b) together with 2-(imino-piperidin-1-yl-methyl)-3-(4-methoxyphenyl)acrylonitrile (4) as intermediate. Also, the reaction of 1a,b with 4 without catalyst afforded 9-methoxy and 9-acetoxy- 3-amino-1-(p-methoxyphenyl)-1H-benzo[f]chromene-2-carbonitrile (3b,e). The reaction of 3a,b with different electrophilic and nucleophilic reagents afforded the 12H-7-oxa-8,10-diazabenzo[ a]anthracene derivatives 5, 9, 10 and 1H-benzo[f]chromene derivatives 6Ð8, 11.

The absolute configurations of new chiral centers in the side chains of diastereomeric 10,11-dihydroquinines, C 20 H 25 BrN 2 O 2 , have been determined. Both diastereomers with either 10R or 10S configuration adopt the conformations in which quinuclidine nitrogen atom points away from the quinoline ring (open conformations). The bulky C3-side chain in the 10R diastereomer hinders intermolecular hydrogen bond formation to the quinuclidinic, more basic nitrogen atom. Instead, the hydrogen bond to the quinolinic N atom is formed which is an unusual case for Cinchona alkaloid crystal packing. The same bulky C3-substituent in the 10S diastereomer does not hinder the common packing mode via intermolecular hydrogen bonding to the quinuclidinic N-atom.

The synthesis and separation of both diastereoisomers of 1-(4-methoxyphenyl)-N-[2- (4-methoxyphenyl)-1-methylethyl]-2-propanamine as markers of clandestine p-methoxyamphetamine have been described. The stereochemistry of the meso diastereomer was established by crystallographic method.