Synthesis and structure of a polyphenylene macrocycle related to "cubic graphite"

[structure: see text] Palladium-catalyzed coupling of 1,2-bis(4-bromophenyl)-3,4,5,6-tetraphenylbenzene and the corresponding hexaphenylbenzene bis(boronic acid) gave a mixture of linear and cyclic oligomers of hexaphenylbenzene. An X-ray crystal structure of the tetrameric oligomer showed it to be the polyphenylene macrocycle 4 (C(168)H(112)). The roughly D(2) symmetric macrocycle contains a large central cavity, and it is one of the channel substructures of "phenylogous cubic graphite".     

Solution-grown crystal of poly[bis(4-isopropylphenoxy)phosphazene]

The structural features of poly[bis(4-isopropylphenoxy)phosphazene] (PB(4-ip)PP) have been studied by electron microscopy, X-ray diffraction and differential scanning calorimetry techniques. Its orthorhombic lattice constants are determined as follows: a = 3,14 nm, b = 1,14 nm, c = 0,992 nm. The space group of this polymer is suggested to be P 2₁2₁2₁–D, and the molecular conformation of the chains possibly to be (trans₃cis)₂. This polymer exhibits a crystal/crystal transition at 86°C below its T(1) transition (120°C). The thermal behavior is similar to the characteristics of poly[bis(p-methoxyphenoxy)phosphazene].     

Rhenium tricarbonyl core complexes of thymidine and uridine derivatives

Thymidine and uridine were modified at the C2' and C5' ribose positions to form amine analogues of the nucleosides (1 and 4). Direct amination with NaBH(OAc)3 in DCE with the appropriate aldehydes yielded 1-{5-[(bis(pyridin-2-ylmethyl)amino)methyl]-4-hydroxytetrahydrofuran-2-yl}-5-methyl-1H-pyrimidine-2,4-dione (L1), 1-{5-[(bis(quinolin-2-ylmethyl)amino)methyl]-4-hydroxytetrahydrofuran-2-yl}-5-methyl-1H-pyrimidine-2,4-dione (L2), and 1-[3-(bis(pyridin-2-ylmethyl)amino)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl]-1H-pyrimidine-2,4-dione (L5), while standard coupling procedures of 1 and 4 with 5-(bis(pyridin-2-ylmethyl)amino)pentanoic acid (2) and 5-(bis(quinolin-2-ylmethyl)amino)pentanoic acid (3) in the presence of HOBT-EDCI in DMF provided a second novel series of bifunctional chelators: 5-(bis(pyridin-2-ylmethyl)amino)pentanoic acid [(3-hydroxy-5-(5-methyl-4-oxo-3,4-dihydro-2H-pyrimidin-1-yl)tetrahydrofuran-2-yl)methyl] amide (L3), 5-(bis(quinolin-2-ylmethyl)amino)pentanoic acid [(3-hydroxy-5-(5-methyl-4-oxo-3,4-dihydro-2H-pyrimidin-1-yl)tetrahydrofuran-2-yl)methyl] amide (L4), 5-(bis(pyridin-2-ylmethyl)amino)pentanoic acid [2-(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-3-yl] amide (L6), and 5-(bis(quinolin-2-ylmethyl)amino)pentanoic acid [2-(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-3-yl] amide (L7). The rhenium tricarbonyl complexes of L1-L4, L6, and L7, [Re(CO)3(LX)]Br (X=1-4, 6, 7: compounds 5-10, respectively), have been prepared by reacting the appropriate ligand with [NEt4][Re(CO)3Br3] in methanol. The ligands and their rhenium complexes were obtained in good yields and characterized by common spectroscopic techniques including 1D and 2D NMR, HRMS, IR, cyclic voltammetry, UV, and luminescence spectroscopy and X-ray crystallography. The crystal structure of complex 6.0.5NaPF6 displays a facial geometry of the carbonyl ligands. The nitrogen donors of the tridentate ligand complete the distorted octahedral spheres of the complex. Crystal data: monoclinic, C2, a = 24.618(3) A, b = 11.4787(11) A, c = 15.5902(15) A, beta = 112.422(4) degrees , Z = 4, D(calc) = 1.562 g/cm3.     

Formation of aryl‐bis (6‐amino‐1,3‐dimethyluracil‐5‐yl) methanes by reaction of 6‐amino‐1, 3‐dimethyluracil with aromatic aldehydes

The synthesis of aryl‐bis(6‐amino‐1,3‐dimethyluracil‐5‐yl)‐methanes 3a‐m by condensation of 6‐amino‐1,3‐dimethyluracil ( 1 ) with aromatic aldehydes 2a‐m at room temperature is reported. The structures of the compounds were established using various spectroscopic analyses and X‐ray crystallography. The crystal structures of two aryl‐bis (6‐amino‐1,3‐dimethyluracil‐5‐yl) methanes are presented.     

A novel, tunable manganese coordination system based on a flexible "spacer" unit: noncovalent templation effects.

The reaction of bis(hexafluoroacetylacetonato)manganese(II) trihydrate (2), an approximately 90 degrees corner unit, with flexible linking unit 4,4'-trimethylenedipyridine (1) allows for the potential formation of three different types of solid-state coordination species: infinite helical polymers, closed dimeric systems, and infinite one-dimensional polymers. While the un-templated starting material is known to give a coordination helix, the other two possible species can be realized through the selective use of a variety of simple, organic guests: toluene (3), diphenylmethane (4), cis-stilbene (5), 1,3-diphenylpropane (6), benzyl alcohol (7), nitrobenzene (8), and cyanobenzene (9). When solutions of 1 and 2 are crystallized in the presence of all of these clathrates, the dimeric macrocycles result in all cases, except for that of 6, in which a syndiotactic, wedge-shaped polymer forms. Employing a linker that is less rigid than is typically used in crystal engineering, such as 1, enables the nucleophilic donor subunit to be more than just a simple "spacer", instead making it an essential, tunable component in the overall crystal lattice. In so doing, a great deal of molecular "information" is lost, but this is compensated for by an in-depth investigation into the weaker host-guest and/or guest-guest interactions, such as nonclassical hydrogen bonding and an assortment of hydrophobic interactions, present in the various systems.     

沙蚕磷草酸盐的合成与晶体结构

合成了一种新的有机磷杀虫剂沙蚕磷[O,O,O',O'-四甲基－S,S'-(2-N,N-二甲氨基-1,3-亚丙基)-双-二硫代磷酸酯],并制备了它的草酸盐。测定了沙蚕磷草酸盐的晶体结构,结果表明,该晶体属三斜晶系,P1空间群,晶胞参数为:a=0.74342(5)nm,b=1.1057(4)nm,c=1.45295(11)nm,α=98.018(11)°,β=101.012(4)°,γ=96.224(10)°,Z=2。通过元素分析,MS、IR及^1H,^1^3CNMR表征了该化合物的结构。     

Charge-transfer forces in the self-assembly of heteromolecular reactive solids: successful design of unique (single-crystal-to-single-crystal) Diels--Alder cycloadditions.

Electron donor/acceptor (EDA) interactions are found to be a versatile methodology for the engineering of reactive heteromolecular crystals. In this way, a series of the charge-transfer pi-complexes between bis(alkylimino)-1,4-dithiin acceptors and anthracene donors are shown to form heteromolecular (1:1) crystalline solids that spontaneously undergo stereoselective [2 + 4] Diels--Alder cycloadditions. The flexible nature of the 1,4-dithiin moiety allows this homogeneous topochemical transformation to proceed with minimal distortion of the crystal lattice. As a result, a unique (single) crystal phase of the Diels--Alder adduct can be produced anti-thermodynamically with a molecular arrangement very different from that in solvent-grown crystals. Such a topochemical reaction between bis(methylimino)-1,4-dithiin and anthracene proceeds thermally and homogeneously up to very high conversions without disintegration of the single crystal. This ideal case of the mono-phase topochemical conversion can be continuously monitored structurally (X-ray crystallography) and kinetically (NMR spectroscopy) throughout the entire range of the crystalline transformation. The resultant "artificial" crystal of the Diels--Alder adduct is surprisingly stable despite its different symmetry and packing mode compared to the naturally grown (thermodynamic) crystal.     

A "classical" tetrahydroxycalix[4]arene adopting the 1,2-alternate conformation

The first example of a "classical" tetrahydroxycalixarene, which adopts the 1,2-alternate conformation both in solution and in the crystal, is described. Calixarene derivatives with two distal methylene groups substituted in a trans fashion by phenyl (5a) or mesityl (5b) groups were synthesized via addition of PhMgBr/CuCN or MesMgBr/CuCN to the bis(spirodiene) derivative 3. Whereas the phenyl-substituted calixarene derivative 5a adopts the usual "cone" conformation, solution NMR data and X-ray crystallography indicate that the more crowded mesityl derivative 5b adopts a 1,2-alternate conformation with the two mesityl groups located at isoclinal positions of the macrocycle.     

Synthese,Struktur und Hydrolyse von Tetrakis(tetrahydropyran)strontium-bis[bis(dimethylisopropylsilyl)phosphanid]

Synthesis, Structures, and Hydrolysis of Tetrakis(tetrahydropyran)strontium Bis[bis(dimethylisopropylsilyl)phosphanide] The metalation of bis(dimethylisopropylsilyl)phosphane in tetrahydropyran with strontium bis[bis(trimethylsilyl)amide] yields almost quantitatively tetrakis(tetrahydropyran)strontium bis[bis(dimethylisopropylsilyl)phosphanide], which crystallizes in the monoclinic space group C2/c (a = 2340.71(1), b = 1028.74(1), c = 2186.02(1) pm, β = 91.03(1)°, Z = 4, wR₂ = 0.0759). The phosphanide ligands are in trans-positions and the P–Sr–P bond angle is found to be 168.5°. Partial hydrolysis of this compound leads to the formation of bis(dimethylsilylisopropylsilyl)phosphane and Sr₄O[P(SiMePr)₂]₆ with a central oxygen atom surrounded tetrahedrally by four alkaline earth metal atoms (monoclinic, space group C2/c, C2/c, a = 2265.83(6), b = 1702.11(5), c = 2462.46(9) pm, β = 91.34(1)°, Z = 4, wR₂ = 0.1057). The edges of the strontium tetrahedron are bridged by phosphanide ligands. The metal atoms are coordinated trigonal planarily by three phosphanide groups.     

(Benzimidazol-1-yl)methyl]benzamides as bifunctional reagents for reliable inorganic-organic supramolecular synthesis

A series of ligands that utilize five-membered N-heterocycles as coordination sites, and the self-complementarity of the carboxamide functionality, have been employed in the supramolecular synthesis of Ag(I)-based extended networks. The crystal structures of eight compounds are reported: bis[4-(2-methylbenzimidazol-1-yl)methylbenzamide]silver(I) tetrafluoroborate hydrate methanol, 1; bis[3-(2-methylbenzimidazol-1-yl)methylbenzamide]silver(I) tetrafluoroborate, 2; bis[4-(5,6-dimethylbenzimidazol-1-yl)methylbenzamide]silver(I) tetrafluoroborate, 3; bis[4-(2-methylbenzimidazol-1-yl)methylbenzamide]silver(I) hexafluoroarsenate methanol, 4; bis[3-(2-methylbenzimidazol-1-yl)methylbenzamide]silver(I) hexafluoroarsenate methanol(0.5), 5; bis[4-(5,6-dimethylbenzimidazol-1-yl) methylbenzamide]silver(I) hexafluoroarsenate, 6; bis[4-(2-methylbenzimidazol-1-yl)methylbenzamide]silver(I) hexafluoroantimonate, 7; and bis[3-(2-methylbenzimidazol-1-yl)methylbenzamide]silver(I) hexafluoroantimonate, 8. An analysis of motifs and structural patterns that result from the primary intermolecular interactions in these structures, reveals that this family of ligands is capable of providing quite reliable means for propagating the linear geometry of the complex ions into extended 1-D architectures via ligand-ligand, N-H...O, hydrogen-bond interactions.     

Bis[N-(trimethylsilyl)iminobenzoyl]phosphanide des Lithiums und Zinks – Synthese sowie NMR-spektroskopische,strukturelle und quantenchemische Untersuchungen

Acyl- and Alkylidenephosphanes. XXXV. Bis[ N -(trimethylsilyl)iminobenzoyl]phosphanides of Lithium and Zinc – Syntheses as well as NMR Spectroscopic, Structural, and Quantumchemical Studies From the reaction of bis(tetrahydrofuran)lithium bis(trimethylsilyl)phosphanide with two equivalents of benzonitrile in 1,2-dimethoxyethane, the yellow dme complex ( 2 a ) of lithium bis[N-(trimethylsilyl)iminobenzoyl]phosphanide ( 2 ) was obtained in 69% yield. However, the intermediate {1-[N-lithium-N-(trimethylsilyl)amido]benzylidene}trimethylsilylphosphane ( 1 ), formed by an analogous 1 : 1 addition in diethyl ether, turned out to be unstable and as a consequence could be characterized by nmr spectroscopic methods only; attempts to isolate the compound failed, but small amounts of the neutral complex 2 b , with the ligands benzonitrile and tetrahydrofuran coordinated to lithium, precipitated. The reaction of compound 2 with zinc(II) chloride in diethyl ether gives the orange-red spiro-complex zinc bis{bis[N-(trimethylsilyl)iminobenzoyl]phosphanide} ( 3 ); this complex is also formed from bis[N-(trimethylsilyl)iminobenzoyl]phosphane ( 4 ), easily amenable by a lithium hydrogen exchange of 2 a with trifluoroacetic acid [18], and zinc bis[bis(trimethylsilyl)amide]. As derived from nmr spectroscopic studies and x-ray structure determinations, compounds 2 a {δ³¹P +63.3 ppm; P2₁/n; Z = 4; R₁ = 0.067}, 2 b {δ³¹P +63.3 ppm; P2₁/c; Z = 4; R₁ = 0.063}, 3 {δ³¹P +58.2 ppm; C2/c; Z = 4; R₁ = 0.037} and 4 {δ³¹P +58.1 ppm [18]} exist as cyclic 3-imino-2λ³σ²-phosphapropenylamides and -propenylamine, respectively, in solution as well as in the solid state. Unlike hydrogen derivative 4 the bis[N-(trimethylsilyl)iminobenzoyl]phosphanide fragments N,N′-coordinating either a lithium or a zinc cation are characterized by almost completely equalized bond lengths; typical mean distances and angles are: PC 180.3 and 178.7; CN 130.5 and 131.8; N–Si 175.3 and 179.3; N–Li 202.3; N–Zn 203.5 pm; CPC 108.8° and 110.5°; PCN 130.9° and 132.9°; CN–Li 113.0°, CN–Zn 117.4°; N–Li–N 104.6°; N–Zn–N 108.8°. Alterations in the shape of the six membered chelate rings, caused by an exchange of the 3-imino-2λ³σ²-phosphapropenylamide or related 2λ³σ²-phospha-1,3-dionate units for the corresponding phosphorus free ligands, are discussed in detail. The results of quantumchemical DFT-B3LYP calculations coincide very well with the experimentally obtained findings.     

Acyl- und Alkylidenphosphane. XXXIV [1]. Methoxycarbonylphosphane – Verbindungen aus dem Umfeld des Phosphaalkins PC?O?Li(dme)2

Acyl- and Alkylidenephosphanes. XXXIV. Methoxycarbonylphosphanes – Compounds closely related to the Phosphaalkyne P?C? O? Li(dme)₂ Whereas methyl fluoroformate reacts with an equimolar amount of bis(tetrahydrofuran)lithium bis(trimethylsilyl)phosphanide ( 1a )

1 Die Numerierung des betreffenden Lithiumphosphanids wird um das Suffix a erweitert, wenn von einer Röntgenstrukturanalyse her Gehalt an koordinierendem Solvens und Konstitution bekannt sind. Nach Möglichkeit beziehen wir uns dann im Text und in den Gleichungen auf derartige Spezies.

in 1,2-dimethoxyethane to give an inseparable mixture of tris(methoxycarbonyl)- ( 3 ) and tris(trimethylsilyl)phosphane, colourless crystals of lithium bis(methoxycarbonyl)phosphanide-1,2-dimethoxyethane (2/3) ( 4a ) are isolated in 84% yield from an analogous reaction with (1,2-dimethoxyethane- O,O ′)lithium phosphanide ( 2a ) in a molar ratio of 2:3. When, however, this ratio is changed to 1:2 or 1:1, the ³¹ P nmr spectra of those solutions show the formation of the by-product lithium methoxycarbonylphosphanide ( 10 ) or methoxycarbonylphosphane ( 6 ) respectively. The function of phosphanide 10 as an important intermediate in the synthesis of the phosphaalkyne P?C? O? Li(dme) ₂ ( Ia ) [1] is discussed in detail. With trifluoroacetic acid in 1,2-dimethoxyethane the diacylphosphanide 4a is converted via a lithium-hydrogen exchange into bis(methoxycarbonyl)phosphane ( 9 ). Unlike 1,3-diketones and other diacylphosphanes [25], solutions of this compound do not show the presence of an enol tautomer even in very unpolar solvents. Tris(methoxycarbonyl)phosphane ( 3 ) obtained in a pure state from methyl chloroformate and phosphanide 2a , might decarboxylate to give the corresponding bis(methoxycarbonyl)methyl derivative 5 when the reaction mixture is worked up. ³¹P and characteristic ³¹C nmr data of these methoxycarbonylphosphanes and their related lithium phosphanides are compared with each other, the tris(phenoxycarbonyl) ( 7 ) and the bis(methoxycarbonyl)phenyl compound 8 being included. An x-ray structure determination (P1 ; a 715.8(2); b = 899.5(1); c = 1262.7(2)pm; α = 99.93(1)°; β = 96.01(1)°; γ = 104.81(1)° at ?100±3°C; Z = 1 dimer; wR₂ = 0.152) shows lithium bis(methoxycarbonyl)phosphanide-1,2-dimethoxyethane (2/3) ( 4a ) to crystallize as a centrosymmetric neutral complex. Either lithium square pyramidally coordinated is bound to both carbonyl oxygen atoms of an almost planar bis(methoxy-carbonyl)phosphanide {Li? O_av. 197.4; O ‥ O 280.9} as well as of an 1,2-dimethoxyethane ligand (210.3; 261.6) and is brigded by another solvent molecule (204.0 pm). Further characteristic average bond lengths and angles are as follows: P$ \ddot - $C 179.5; C$ \ddot - $O 122.2; C? O 136.5; O? CH₃ 143.2 pm; C$ \ddot - $P$ \ddot - $C 98.8°; P$ \ddot - $C$ \ddot - $O 132.5°; P$ \ddot - $C? O 107.9°.     

Transition Metal Complexes of p-Sulfonatocalix[5]arene

The X-ray crystal structure of the p-sulfonatocalix[5]arene(5)(-) anion (1b) in the form of the dimeric hydrate Na(10)[p-sulfonatocalix[5]arene](2).33.5H(2)O (2) is reported. The reactions of 1b with a number of transition metal salts to form transition metal bridged bis(calixarene) inclusion complexes have also been investigated. The X-ray crystal structure of the "Co(H(2)O)(4)(2+)" bridged species Na(8)[Co(H(2)O)(4)(p-sulfonatocalix[5]arene)(2)].2CH(3)C(O)N(CH(3))(2).37H(2)O (3) which incorporates a "supercavity" large enough to encompass 2 N,N-dimethylacetamide (dma) guest molecules as well as ca. 15 water molecules and Na(+) ions is reported. Crystal data are as follows: for 2, monoclinic space group P2(1)/c, Z = 4, a = 22.0644(4), b = 19.1180(3), c = 27.7834(4) ?, beta = 91.780(1), V = 11714.1(5) ?(3); complex 3, orthorhombic space group Pnma, Z = 4, a = 22.2271(5), b = 30.1693(6), c = 18.8503(4) ?, V = 12640.6(5) ?(3).     

Structure and properties of bis{[2-(4-<Emphasis Type="Italic">tert</Emphasis>-butyl)phen]ethyl}phosphine sulfide

Previously unknown bis[2-(4-tert-butyl)phen]ethylphosphine sulfide is obtained with a high yield from 4-tert-butyl styrene, red phosphorus, and elemental sulfur. Using single crystal XRD, multinuclear NMR, IR, and UV spectroscopy, it is found that the phosphorus atom is four-coordinated in the bis[2-(4-tert-butyl)phen]ethylphosphine sulfide molecule (regardless of the phase state of the compound: crystal, solution). By the example of phosphorylation of bis[2-(4-tert-butyl)phen]ethylphosphine sulfide acetylene in the KOH-DMSO system it is shown that the reaction proceeds by double addition with the participation of phosphorus-centered nucleophiles.     

Synthesis, characterization and coordination properties of bis(alkyl)selenosalen ligands

New bis (alkyl) selenosalen podand ligands having Se2N2 donor sites have been synthesized by the condensation of unsymmetrical o-formylphenyl alkyl selenide (1-3) with ethylenediamine. The reaction of bis(alkyl)selenosalen podands with Pd(II) and Pt(II) afforded selenoether-selenolate coordination complexes 7-10via cleavage of one of the two Se-C(alkyl) bonds of bis(alkyl)selenosalen podands upon complexation. DFT calculations revealed that the cleavage of Se-C(alkyl) bonds occurred possibly via S(N)2 mechanism instead of a sequence of oxidative addition and reductive elimination reactions. The spectral data and elemental analyses confirmed the formation of selenoether-selenolate complexes. The structures of the podands N,N'-bis[(2-methylseleno)phenylmethylene]-1,2-ethanediamine (4), N,N'-bis[(2-decylseleno)phenylmethylene]-1,2-ethanediamine (5) and the selenoether-selenolate complex 8 have been determined by single crystal X-ray diffraction analysis. The crystal structure of 5 showed SeH interaction with a ladder like 3D supramolecular arrangement via interdigitation of long alkyl chains. Comparison of crystal packing of podands 4 and 5 indicates that the alkyl chain length has significant impact on the crystal packing. The platinum selenolate complex 8 shows a square planar arrangement around the Pt centre, where the Se atoms in the selenolate and the selenoether have nearly equal Pt-Se bond length.     

Trimethylsilylverbindungen der Vb-Elemente. VII. Die Kristallstrukturen von Lithium-bis(trimethylsilyl)bismutid · DME und Tetrakis(trimethylsilyl)dibismutan sowie Bemerkungen zur Kristallstruktur des Bis(4-methoxyphenyl)ditellans

Trimethylsilyl Derivatives of Vb Elements. VII. Crystal Structures of Lithium Bis(trimethylsilyl)bismuthide · DME and of Tetrakis(trimethylsilyl)dibismuthane as well as Some Comments on the Crystal Structure of Bis(4-methoxyphenyl)ditellane Colourless lithium bis(trimethylsilyl)bismuthide · DME

1 1,2-Dimethoxyethan (DME); Tetrahydrofuran (THF)

1 and green, metallic lustrous tetrakis(trimethylsilyl)dibismuthane 2 crystallize isotopic to their antimony homologues [1, 2]. As it is shown by crystal structure determinations { 1 : ?90°C; I 4 2d; a = 1017,3(4); c = 3738,0(26) pm; Z = 8; R _w = 0,065; 2 : + 20°C; P2 ₁ /c; a = 680,9(4); b = 1704,8(13); c = 1197,9 (10) pm; β = 119,46(6)°; Z = 2; R _w = 0,084} both compounds form chains which in the case of bismuthide 1 are built up as screws of alternating bismuth and lithium atoms; bonding further to two trimethylsilyl groups or to the chelating DME ligand both atoms gain coordination number 4 {Li? Bi 292(3); Bi? Si 263.3(14) pm; Bi? Li? Bi 132(1); Li? Bi? Li 148(1); φ(Li? Bi? Li? Bi) 83°}. In the case of dibismuthane 2 the centrosymmetric molecules are strung, their Bi-Bi groups forming nearly linear zigzag chains with shortened intermolecular contact distances {Bi-Bi 303.5(3); Bi …? Bi 380.4(3); Bi? Si 268 pm; Bi? Bi …? Bi 169; Bi? Bi? Si 97.4(5) and 92.0(5)°}. Structure and properties of 2 are compared with those of similar compounds; the crystal structure of brown, green metallic lustrous bis(4-methoxyphenyl)ditellane 5 already published by Ludlow and McCarthy[3] is reinvestigated with respect to very short intermolecular Te…?Te contacts.     

Reaction of N,N′-Dialkyl Selenium Diimides with Bis(amino)stannylenes — Formation of a Tin-Tin Bond

N,N′-Dialkyl selenium diimides 1 , R(NSeN)R [R = tBu ( a ), tOct ( b )], react with bis(amino)stannylenes such as 1,3-di-tert-butyl-4,4-dimethyl-1,3,4,2λ²-diazasilastannetidine ( 2 ), 1,3-di-tert-butyl-4,4,5,5-tetramethyl-1,3,4,5,2λ²-diazadisila-stannolidine ( 3 ), bis[tert-butyl(trimethylsilyl)amino]stannylene ( 4 ) and bis[bis(trimethylsilyl)amino]stannylene ( 5 ) in a 1 : 1 ratio. The products are either the spiro-tin(IV) compounds 6 and 7 , consisting of the respective cyclic bis(amino)stannylene and a four-membered ring, or the analogous four-membered 1,2,4,3-selenadiazastannetidine rings 8 and 9 with the amino groups linked to the tin atom. Only in the case of the four-membered cyclic stannylene 2 , two equivalents of 2 may also react with 1 a to a polycyclic compound 10 : Two molecules of 2 are linked by a tin-tin bond and this bond is bridged by the NSeN group, to give a five-membered ring with close Sn? Se contacts. All products were characterized by multinuclear magnetic resonance spectroscopy (¹H, ¹³C, ¹⁵N, ²⁹Si, ⁷⁷Se, ¹¹⁹Sn NMR) in solution, and the molecular structure of the polycyclic compound 10 was determined by single crystal X-ray analysis [monoclinic; space group C2/c; a = 3 294.1(3), b = 1 321.5(3), c = 1 855.9(2) pm and β = 98.02(2)°].     

An "S"-shaped pentanuclear CuII cluster derived from the metal-assisted hydrolysis of pyCOpyCOpy: structural, magnetic and spectroscopic studies

Reaction of [Cu2(O2CMe)4(H2O)2] with 2,6-di-(2-pyridylcarbonyl)-pyridine (pyCOpyCOpy or dpcp) in MeCN-H2O 10:1, led to the pentanuclear copper(II) complex [Cu5(O2CMe)6{pyC(O)(OH)pyC(O)(OH)py}2] () which crystallizes in the triclinic P1 space group. The copper(II) atoms are arranged in an "S"-shaped configuration, and are bridged by the doubly deprotonated bis(gem-diol) form of the ligand, pyC(O)(OH)pyC(O)(OH)py2-. Magnetic susceptibility data indicate the interplay of both ferro- and antiferromagnetic intramolecular interactions stabilizing an S=3/2 ground state. Fitting of the data according to a next-nearest-neighbour model {H=-[J1(S1S2+S1'S2')+J2(S2S3+S3'S2')+J3(S1S3+S3'S1')+J4(S2S2')]} yields exchange coupling constants J1=+39.7 cm(-1), J2=-15.9 cm(-1), J3=-8.3 cm(-1) and J4=+4.3 cm(-1), leading to an S=3/2 ground state. X-Band EPR spectroscopy indicates a zero-field splitting of the ground state with |D3/2|=0.38 cm(-1).     

Schlenk's early "free" carbanions

Nearly a century ago, Schlenk published the syntheses and isolation of two most remarkable and unstable complexes: crystalline [Ph(3)C(-)][Me(4)N(+)] and [PhCH(2) (-)][Me(4)N(+)]. The crystal structure of the first complex contains a "free" Ph(3)C(-) ion, which displays the expected planar trigonal geometry at its central carbon atom. The phenyl groups are not orientated in the typical propeller arrangement, but instead display various orientations with respect to the molecular plane. These orientations can be directly related to the extent of charge delocalization and correlate well with other structural characteristics related to charge delocalization. The crystal structure also shows a network of C-H(delta+)...C(delta-) and C-H...pi interactions. Only C-H...pi interactions to the most negative charged phenyl rings are observed. The absolute Br?nsted acidity of Me(4)N(+) is calculated by the G2(MP2) method (287.7 kcal mol(-1)) and is compared to the calculated acidity of Me(4)P(+) (268.4 kcal mol(-1)). On this basis, the pK(a) value for Me(4)N(+) is estimated at 29.6. This makes the existence, and especially Schlenk's early isolation, of the "free" carbanions [Ph(3)C(-)][Me(4)N(+)] and [PhCH(2) (-)][Me(4)N(+)] quite noteworthy.     

Synthesis of fluorinated geminal diisocyanides stabilized on a transition metal

Chromium complexes of the geminal diisocyanides bis(pentacarbonyl)-μ-2,2-diisocyano-1,1,1,3,3,3-hexafluoropropane)dichromium 1a and bis(pentacarbonyl)-μ-2,2-diisocyano-1,1,1,3,3-pentafluorobutane)dichromium 1b were obtained by radical alkylation of pentacarbonylcyanochromate besides pentacarbonyl(2-isocyano-1,1,1,3,3,3-hexafluoropropane)chromium 2a and pentacarbonyl(2-isocyano-1,1,1,3,3-pentafluorobutane)chromium 2b, respectively. Pentacarbonyl(2-isocyano-1,1,1,2,3,3,3-heptafluoropropane)chromium 2c was prepared analogously. The crystal and molecular structures of 1a and b were determined by X-ray diffraction.