Unusual face-to-face pi-pi stacking interactions within an indigo-pillared M3(tpt)-based triangular metalloprism

A triangular metalloprism, [((CO)3Re(mu-2)Re(CO)3)3(mu3-1)2], self-assembled from Re2(CO)10, 2,4,6-tri-4-pyridyl-1,3,5-triazine (tpt, 1), and indigo (H2(2)), represents a fairly novel example of strong face-to-face pi-pi interactions between the central triazine rings of the tpt ligands that bow significantly inward distorting the prismatic structure.     

Untersuchungen zur Metallierung der Cyclophosphane P4(Cme3)3(Sime3), P4(Cme3)2(Sime3)2, P4(Sime3)4

Investigations Concerning the Metallation of the Cyclotetraphosphanes P₄(Cme₃)₃(Sime₃), P₄(Cme₃)₂(Sime₃)₂, and P₄(Sime₃)₄ The reaction of white phosphorus with LiCme₃ and me₃SiCl yields P₄(Sime₃)(Cme₃)₃ 1 . With n-buLi this crystalline cyclotetraphosphane forms the crystalline LiP₄(Cme₃)₃. In the same manner, n-buLi, with trans-P₄(Sime₃)₂(Cme₃)₂ 2 to yields LiP₄(Sime₃)(Cme₃)₂, which in contrast to LiP₄(Cme₃)₃ decomposes within a few hours yielding P(Sime₃)₂n-bu 6 , P(Sime₃)₃ 8 , LiP(Sime₃)₂ 9 and also the cyclic compounds P₄(Sime₃)(Cme₃)₃ 10 , LiP₄(Cme₃)₃ 11 and LiP₃(Cme₃)₂ 12 . The composition of the product mixture depends on the molar ratio of 2 to LiC₄H₉. At a molar ratio of 1:1 11 and 12 are not jet observed. At molar ratios of 1:1.5 and 1:2 P(Sime₃)₃ is not found. The amount of 11 and 12 grows with increasing concentration of n-buLi. On addition of n-buLi the solution of P₄(Sime₃)₄ immediately turns red. Li₃P₇ and Li₂P₇(Sime₃) (among others) are formed so fast that the first intermediates in the lithiation sequence so far could not be elucidated. These results demonstrate clearly that replacement of two me₃Si groups in P₄(Sime₃)₄ by two me₃C groups excludes the rearrangement of LiP₄(Sime₃)(Cme₃)₂ to a P₇-molecule.     

Ni(tpt)(NO3)2—A Three-Dimensional Network with the Exceptional (12,3) Topology: A Self-Entangled Single Net

The shortest circuits in the three-dimensional network with (12,3) topology of solvated Ni(tpt)(NO₃)₂ pass through one another (see picture). This network based upon interlinked double helices occupies a unique position in the set of (n,3) nets. tpt=tri-4-pyridyl-1,3,5-triazine.     

Force-constant calculations for Ni(PF3)4, Pd(PF3)4 and Pt(PF3)4

Force constants for a SVFF approximation have been obtained for the compounds Ni(PF₃)₄, Pd(PF₃)₄ and Pt(PF₃)₄ using the FG matrix method and vibrational assignments (A₁, E and F₂ symmetry species) on the basis of regular tetrahedral symmetry, point group T_d. Six primary force constants involving bond stretching and bond angle changes and five interaction force constants were used to simultaneously fit the observed wavenumbers. The PF stretching force constant differs by only ± 3% for all three compounds and for the free ligand, PF₃. The metal—phosphorus stretching force constant, however, increases significantly in the order Ni < Pd < Pt, and is 65% larger for Pt(PF₃)₄ than for Ni(PF₃)₄. These changes are discussed in terms of the metal—phosphorus—fluorine bonding in M(PF₃)₄ compounds.     

Syntheses and structures of the infinite chain compounds Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14)

The alkali metal/group 4 metal/polychalcogenides Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) have been synthesized by means of the reactive flux method at 823 or 873 K. Cs(4)Ti(3)Se(13) crystallizes in a new structure type in space group C(2)(2)-P2(1) with eight formula units in a monoclinic cell at T = 153 K of dimensions a = 10.2524(6) A, b = 32.468(2) A, c = 14.6747(8) A, beta = 100.008(1) degrees. Cs(4)Ti(3)Se(13) is composed of four independent one-dimensional [Ti(3)Se(13)(4-)] chains separated by Cs(+) cations. These chains adopt hexagonal closest packing along the [100] direction. The [Ti(3)Se(13)(4-)] chains are built from the face- and edge-sharing of pentagonal pyramids and pentagonal bipyramids. Formal oxidation states cannot be assigned in Cs(4)Ti(3)Se(13). The compounds Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) crystallize in the K(4)Ti(3)S(14) structure type with four formula units in space group C(2)(h)()(6)-C2/c of the monoclinic system at T = 153 K in cells of dimensions a = 21.085(1) A, b = 8.1169(5) A, c = 13.1992(8) A, beta = 112.835(1) degrees for Rb(4)Ti(3)S(14);a = 21.329(3) A, b = 8.415(1) A, c = 13.678(2) A, beta = 113.801(2) degrees for Cs(4)Ti(3)S(14); a = 21.643(2) A, b = 8.1848(8) A, c = 13.331(1) A, beta = 111.762(2) degrees for Rb(4)Hf(3)S(14); a = 22.605(7) A, b = 8.552(3) A, c = 13.880(4) A, beta = 110.919(9) degrees for Rb(4)Zr(3)Se(14); a = 22.826(5) A, b = 8.841(2) A, c = 14.278(3) A, beta = 111.456(4) degrees for Cs(4)Zr(3)Se(14); and a = 22.758(5) A, b = 8.844(2) A, c = 14.276(3) A, beta = 111.88(3) degrees for Cs(4)Hf(3)Se(14). These A(4)M(3)Q(14) compounds (A = alkali metal; M = group 4 metal; Q = chalcogen) contain hexagonally closest-packed [M(3)Q(14)(4-)] chains that run in the [101] direction and are separated by A(+) cations. Each [M(3)Q(14)(4-)] chain is built from a [M(3)Q(14)] unit that consists of two MQ(7) pentagonal bipyramids or one distorted MQ(8) bicapped octahedron bonded together by edge- or face-sharing. Each [M(3)Q(14)] unit contains six Q(2)(2-) dimers, with Q-Q distances in the normal single-bond range 2.0616(9)-2.095(2) A for S-S and 2.367(1)-2.391(2) A for Se-Se. The A(4)M(3)Q(14) compounds can be formulated as (A(+))(4)(M(4+))(3)(Q(2)(2-))(6)(Q(2-))(2).     

LiFe(MoO4)2, LiGa(MoO4)2 and Li3Ga(MoO4)3

The structures of lithium iron dimolybdate, LiFe(MoO₄)₂, and lithium gallium dimolybdate, LiGa(MoO₄)₂, are shown to be isomorphous with each other. Their structures consist of segregated layers of LiO₆ bicapped trigonal bipyramids and Fe(Ga)O₆ octahedra separated and linked by layers of isolated MoO₄ tetrahedra. The redetermined structure of trilithium gallium trimolybdate, Li₃Ga(MoO₄)₃, shows substitional disorder on the Li/Ga site and consists of perpendicular chains of LiO₆ trigonal prisms and two types of differently linked Li/GaO₆ octahedra.     

Conformational analysis of the series of 3(4)-halogen-substituted caran-4(3)-ols and 3-methylnorcaran-4(3)-OLS by their spectra

Conclusions As a rule, the equilibrium of the skewed twist conformera is observed for the 3(4)-halogen-substituted caran-4(3)-ols and 3-methylnorcaran-4(3)-ols. This is indicated by the simultaneous presence of the bands of OH of the free OH groups and the OH groups bound by intramolecular hydrogen bonds. The steric interactions of the 7-R groups with the cis substituents at C³ and C⁴ and the intramolecular hydrogen bonds OH... Hal and OH... cyclopropane ring play a role in the realization of one or the other form. In the case of uniform substitution, the influence of the halogens on OH changes in the series F相似文献   

K3Ga2(PO4)3 and Na3Ga(PO4)2

The structures of tripotassium digallium tris(phosphate), K₃Ga₂(PO₄)₃, and trisodium gallium bis(phosphate), Na₃Ga(PO₄)₂, have different irregular one‐dimensional alkali ion‐containing channels along the a axis of the orthorhombic and triclinic unit cells, respectively. The anionic subsystems consist of vortex‐linked PO₄ tetrahedra and GaO₄ tetrahedra or GaO₅ trigonal bipyramids in the first and second structure, respectively.     

NMR studies of 4(3H)-quinazolinones and 4(3H)-quinazolinethiones

Summary Unambiguous¹H and¹³C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the¹³C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.

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Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen

Zusammenfassung Die¹H- und¹³C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.

     

First characterization of the ammine-ammonium complex [(NH4(NH3)4)2(mu-NH3)2]2+ in the crystal structure of [NH4(NH3)4][B(C6H5)4].NH3 and the [NH4(NH3)4]+ complex in [NH4(NH3)4][Ca(NH3)7]As3S6.2NH3 and [NH4(NH3)4][Ba(NH3)8]As3S6.NH3

The compound [NH4(NH3)4][B(C6H5)4].NH3 (1) was prepared by the reaction of NaB(C(6)H(5))(4) with a proton-charged ion-exchange resin in liquid ammonia. [NH(4)(NH(3))(4)][Ca(NH(3))(7)]As(3)S(6).2NH(3) (2) and [NH4(NH3)4][Ba(NH3)8]As3S6.NH3 (3) were synthesized by reduction of As(4)S(4) with Ca and Ba in liquid ammonia. All ammoniates were characterized by low-temperature single-crystal X-ray structure analysis. They were found to contain the ammine-ammonium complex with the maximal possible number of coordinating ammonia molecules, the [NH4(NH3)4]+ ion. 1 contains a special dimer, the [(NH4(NH3)4)2(mu-NH3)2]2+ ion, which is formed by two[NH4(NH3)4]+ ions linked by two ammonia molecules. The H(3)N-H...N hydrogen bonds in all three compounds range from 1.82 to 2.20 A (DHA = Donor-H...Acceptor angles: 156-178 degrees). In 2 and 3, additional H(2)N-H...S bonds to the thioanions are observed, ranging between 2.49 and 3.00 A (DHA angles: 120-175 degrees). Two parallel phenyl rings of the [B(C(6)H(5))(4)](-) anion in 1 form a pi...pi hydrogen bond (C...C distance, 3.38 A; DHA angles, 82 degrees), leading to a dimeric [B(C6H5)4]2(2-) ion.     

Synthesis and some transformations of N-cyclohexyl-3(4)-chloro-4(3)-methylthiobutyramides

Addition of methylsulfenyl chloride to N-cyclohexyl-3-butenamide yields N-cyclohexyl-4-chloro-3-methylthiobutyramide. Isomerization, oxidation of the latter, and β-elimination were studied.     

Peculiar transformation of a nonaromatic Al(4)Cl(4)(NH(3))(4) into an aromatic Na(2)Al(4)Cl(4)(NH(3))(4)

We analyzed the molecular orbitals for a Al(4)Cl(4)(NH(3))(4) compound, which is a model of the (AlBr x NEt(3))(4) crystal structure recently reported by Schn?ckel and co-workers. We found that even though Al(4)Cl(4)(NH(3))(4) contains a planar square Al(4) cluster it is not an aromatic compound. However, the addition of two sodium atoms to Al(4)Cl(4)(NH(3))(4) yields a new Na(2)Al(4)Cl(4)(NH(3))(4) compound which is a pi-aromatic molecule. We hope that prediction of this new compound will facilitate a synthesis of aluminum aromatic solids.     

Thermal behaviour and vibrational spectra of (NH4)3Ga(C2O4)3 · 3H2O and (NH4)3Al(C2O4)3 · 3H2O

The IR and Raman spectra and the thermal behaviour of the isomorphous compounds (NH₄)₃Ga(C₂O₄)₃·3H₂O and (NH₄)₃Al(C₂O₄)₃·3H₂O were investigated. Detailed stoichiometries, sustained by TG, DTA and IR spectroscopic analyses, were found in both cases. Different results, associated with the different polarizing powers of the metal cations, were obtained. The first evidence was found of the formation of basic gallium carbonates.     

Purification and Magnetic Interrogation of Hybrid Au-Fe(3) O(4) and FePt-Fe(3) O(4) Nanoparticles

Purifying heterodimers: Differential magnetic catch and release separation is used to purify two important hybrid nanocrystal systems, Au-Fe(3) O(4) and FePt-Fe(3) O(4) . The purified samples have substantially different magnetic properties compared to the as-synthesized materials: the magnetization values are more accurate and magnetic polydispersity is identified in morphologically similar hybrid nanoparticles.     

EPR of gamma irradiated (CH3)3NHClO4, (CH3)3NHBF4 and [(CH3)4N]2ZnCl4 single crystals

Gamma irradiation damage centres in (CH₃)₃NHClO₄, (CH₃)₃NHBF₄ and [(CH₃)₄N]₂ZnCl₄ were investigated by electron paramagnetic resonance spectroscopy at room temperature. The centres were found to be (CH₃)₃N^+. and the hyperfine structure parameters for methyl protons and the nitrogen nucleus were determined. The results indicated that the (CH₃)₃N^+. radical wholly performs reorientational motions around its C_3v axis in addition to the reorientatonal motions of the methyl groups around their C_3v axes. These results were compared with the earlier studies on (CH₃)₃N^+. radical and discussed. Low temperature measurements on the first two of the title compounds were assessed.