Synthesis and molecular and crystal structures of new cation-anionic hypervalent germanium complexes with 1,1,3,3-tetrakis(O—Ge)chelato-1,1,3,3-tetra(lactamomethyl)-1,3-digermoxane dications

The reaction of dichloride (L⁵)₂GeCl₂ with LiI·H₂O under conditions, which did not exclude exposure to atmospheric oxygen, as well as hydrolysis of chloride triflate (L⁷)₂Ge(Cl)OTf in the presence of Et₃N and of perchlorate (L⁵)₂Ge(Cl)OClO₃ by atmospheric moisture afforded cation-anionic complexes containing the digermoxane dications of the general formula [(L ⁿ )₂GeOGe(L ⁿ )₂]²⁺ (L ⁿ is a lactamomethyl n-membered bidentate C,O-coordinating ligand) with the triiodide, triflate, and perchlorate ions, respectively. According to the results of X-ray diffraction study, the digermoxane dications in these complexes contain two pentacoordinate Ge atoms each and occur as germylium ions stabilized by two OGe coordination bonds. In these complexes, the digermoxane dications are diastereomers in which the bischelate systems have opposite configurations.     

Synthesis and crystal and molecular structures of six-coordinate tin dibromides and diiodides containing lactamomethyl C,O-chelating ligands

New (O−Sn)-bischelate bis(lactamomethyl)dibromo- and-diiodostannanes [L⁽ⁿ⁾]₂SnX₂ (L is the bidentate lactamomethyl C,O-chelating ligand;n is the size of the lactam ring, 5–7; X=Br or I) were prepared both by the direct method from metallic tin and the correspondingN-(halomethyl)lactams and by the reactions of dichlorides [L⁽ⁿ )]₂SnCl₂ with lithium halides. According to the data of X-ray diffraction analysis, the tin atom in [L⁽ⁿ⁾]₂SnBr₂ (n=5–7) and [L⁽ⁿ⁾]₂SnI₂ (n=5 or 6) adopts an octahedral configuration with the carbon atoms intrans positions and the coordinating oxygen and halogen atoms incis-positions with respect to each other. A comparison with the structures of analogous lactamomethyl halide derivatives of five-and six-coordinate Si, Ge, and Sn demonstrates that the spatial structures of the hypervalent fragments containing six-coordinate atoms are less sensitive to the replacement of the halide ligands and the central atom. The covalence of the M−Hal bond increases and the covalence of the M−O bond decreases in the series M=Si, Ge, and Sn. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1988–1998, October, 1999.     

Crystal and molecular structures of six-coordinate germanium difluorides and dibromides containing lactamomethyl C,O-chelating ligands

The structures of (O−Ge)-bischelate bis(lactamomethyl)difluoro- and-dibromogermanes [L⁽ⁿ⁾]₂GeX₂, where L is the bidentate lactamomethyl C,O-chelating ligand,n=5–7 (the size of the lactam ring), and X=F or Br, were studied by X-ray diffraction analysis. The six-coordinate Ge atom in these compounds is involved in two hypervalent X−Ge−O bonds whose parameters are compared with the corresponding values in analogous dichlorides and five-coordinate Ge derivatives. On going from difluorides to dichlorides and then to dibromides, the coordination environment about the Ge atom approaches the ideal octahedron. An analogous effect is observed as the size of the lactam ring increases. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1799–1805, October, 2000.     

Crystal and Molecular Structure of (trans-3,4-Diamino-2,2,6,6-tetramethylpiperidine-1-oxyl-N3, N4)(oxalato-O,O′)platinum(II) Dihydrate

The crystal and molecular structure of (trans-3,4-diamino-2,2,6,6-tetramethylpiperidine-1-oxyl-N ³, N ⁴)(oxalato-O,O′)platinum(II) dihydrate was studied by single crystal X-ray diffraction. The crystals belong to the monoclinic system; a 8.261, b 13.129, c 15.224 Å; β 104.29°, Z 4, space group P2₁/n. The structure was solved by the direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R 0.026 for all the 3660 measured unique reflections. The structure consists of individual mononuclear bischelate molecules containing two different bidentate ligands. The Pt²⁺ coordination is distorted square-planar. The complex molecules and water molecules in the crystal of I are linked by hydrogen bonds forming an infinite 3D network. __________ Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 11, 2005, pp. 1893–1897. Original Russian Text Copyright ? 2005 by Chekhlov.     

Contribution to the Protonation of a Calix[4]arene: DFT Calculated Structure of Protonated <Emphasis Type="Italic">p-tert</Emphasis>-Butylcalix[4]arenetetrakis(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethylacetamide)

Summary. By using DFT calculations, the most probable structure of the p-tert-butylcalix[4]arenetetrakis(N,N-diethylacetamide) · H₃O⁺ complex species was derived. In this complex, the hydroxonium ion H₃O⁺ is predominantly bound by strong hydrogen bonds to three phenoxy oxygens of the ligand and partly to the remaining phenoxy oxygen atom by two somewhat weaker hydrogen bonds. Besides, the H₃O⁺ cation is also bound to two carbonyl oxygens of the mentioned ligand by further two weaker hydrogen bonds.     

Contribution to the Protonation of a Calix[4]arene: DFT Calculated Structure of Protonated p-tert -Butylcalix[4]arenetetrakis( N , N -diethylacetamide)

By using DFT calculations, the most probable structure of the p-tert-butylcalix[4]arenetetrakis(N,N-diethylacetamide) · H₃O⁺ complex species was derived. In this complex, the hydroxonium ion H₃O⁺ is predominantly bound by strong hydrogen bonds to three phenoxy oxygens of the ligand and partly to the remaining phenoxy oxygen atom by two somewhat weaker hydrogen bonds. Besides, the H₃O⁺ cation is also bound to two carbonyl oxygens of the mentioned ligand by further two weaker hydrogen bonds.     

Synthesis and molecular and crystal structures of mono-and bis-chelate hypercoordinate silicon compounds containing the C,O-chelating 2,2-dimethyl-4-oxo-2,3-dihydro-1,3-oxazin-3-ylmethyl ligand

New mono-and bis-chelate hypercoordinate silicon complexes containing the monoanionic C,O-chelating 2,2-dimethyl-2,3-dihydrobenzo-1,3-oxazin-3-ylmethyl (BonCH₂) ligand were synthesized starting from 2,2-dimethyl-2,3-dihydrobenzo-1,3-oxazin-4-one (1) through its TMS derivative 2. The reactions of compound 2 with the chlorosilylmethylating agents ClCH₂SiMe₂Cl, ClCH₂SiMeCl₂, and (ClCH₂)₂SiCl₂ followed by the transformations of the initially formed chlorosilanes BonCH₂SiMe₂Cl (3), BonCH₂SiMeCl₂ (6), and [(BonCH₂)₂Si(Cl)]⁺Cl⁻ (8), respectively, into the target products afforded neutral monochelates, viz., monofluoride BonCH₂SiMe₂F (5) and difluoride BonCH₂SiMeF₂ (7), and the bis-chelate disiloxane cation-anion complexes {[(BonCH₂)₂Si]₂O}²⁺·Cl⁻·ClHCl⁻ (9) and {[(BonCH₂)₂Si]₂O}²⁺·2TfO⁻ (10). The reaction of ditriflate 10 with boron trifluoride etherate produced fluoride triflate (BonCH₂)₂Si(F)OTf (11). The X-ray diffraction study of compounds 5, 7, 9, 10, and 11, as well as of NH-heterocycle 1 and disiloxane (BonCH₂SiMe₂)₂O (4) studied earlier, demonstrated that the Si atoms in complexes 5, 7, 9, and 10 are pentacoordinate through the formation of an intramolecular O→Si bond. The coordination of silicon in fluoride triflate 11 can be described as 5+1. In disiloxane 4, one of two Si atoms is pentacoordinate. Dinuclear cation-anion complexes 9 and 10 contain the diastereomeric bis-silylium ions {[(BonCH₂)₂Si]₂O}²⁺, which differ in the configuration of the chiral bis-chelate fragments (BonCH₂)₂Si. In complex 9, these fragments have opposite configurations (ΛΔ); in ditriflate 10, the same configurations (ΛΛ). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 446–458, March, 2007.     

1,3‐Propane­di­ammonium tetra­thio­tungstate and N,N,N′,N′‐tetra­methyl­ethyl­enedi­ammonium tetra­thio­tungstate

The title complexes, (C₃H₁₂N₂)[WS₄] and (C₆H₁₈N₂)[WS₄], contain tetrahedral [WS₄]²⁻ dianions, which accept a complex series of hydrogen bonds from the organic dications. The strength and number of these hydrogen bonds affect the W—S distances.     

A Proton Complex of p-tert-Butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide): NMR Evidence and Probable Structure

Using ¹H and ¹³C NMR together with density functional theoretical (DFT) calculations, it is shown that p-tert-butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide) (1) forms a stable equimolecular complex with proton in the form of hydroxonium ion in nitrobenzene-d ₅. Protons were offered by hydrogen bis(1,2-dicarbollyl) cobaltate (HDCC) and converted to hydroxonium ions by traces of water. The complex 1·H₃O⁺ adopts a slightly asymmetric but rapidly motionally averaged conformation, which is distinctly more cone-like than ligand 1. The hydroxonium ion H₃O⁺ is bound partly to thiocarbonyl sulphur atoms and partly to phenoxy oxygen atoms of 1 by strong hydrogen bonds and other electrostatic interactions.

     

Synthesis and Crystal Structure of a Tetranuclear Molybdenum(II) Silylamido Cluster

Treatment of molybdenum(II) chloride with the difunctional silylamide Li₂Me₂Si(NPh)₂ led to the formation of the tetranuclear cluster compound [Mo₄{Me₂Si(NPh)₂}₄]. According to the X-ray crystal structure determination, the central core of the cluster consists of four molybdenum atoms in a nearly rectangular arrangement. There are two μ₄-κ-N,N,N',N'-Me₂Si(NPh)₂^2– ligands capping the Mo₄ rectangle and two μ₂-Me₂Si(NPh)₂^2– ligands located at opposite edges. The alternating Mo–Mo distances of 218.1(1) and 279.5(1) pm indicate the presence of a cyclobutadiyne type cluster with alternating Mo–Mo triple and single bonds.     

Protonated Co(III) Complexes with Ethylenediaminetetraacetic and S-Proline-N-Mono-3-propionic Acids. Crystal Structures of (H3O)[Co(HEdta)(CN)] · H2O and [Co(Promp)(HPromp)] · H2O

Crystal structures of [Co(Promp)(Hpromp)] · H₂O (I) (where Promp and Hpromp are deprotonated and monoprotonated anions of S-proline-N-mono-3-propionic acid) and (H₃O)[Co(Hedta)(CN)] · H₂O (II) (where HEdta is monoprotonated anion of ethylenediaminetetraacetic acid) are determined by X-ray diffraction method. The Co coordination octahedron in compound I is formed by two N atoms in trans-positions and by four O atoms of two tridentate ligands, i.e., anions of H₂Promp acid, one of which is fully deprotonated, while the other one has protonated carboxyl group of a six-membered aminopropionate metal cycle. Neutral [Co(Promp)(Hpromp)] complexes and water molecules are united by hydrogen bonds into chains along 2₁ screw axis. Crystals II consist of the complex anions [Co(Hedta)(CN)]⁻, hydroxonium cations, and water molecules. The Co coordination octahedron includes two N atoms and three O atoms of ion of ethylenediaminetetraacetic acid, whose one acetate group is not coordinated but protonated; cyanide ion lies in the NCoN plane. Crystals II contain two types of H₃O⁺ ions that are involved in hydrogen bonds in different way.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 596–605.Original Russian Text Copyright © 2005 by Poznyak, Burshtein.     

A new coordination complex based on a polynitrile ligand: bis(4‐amino‐3,5‐di‐2‐pyridyl‐4H‐1,2,4‐triazole)diaquairon(II) bis(1,1,3,3‐tetracyano‐2‐methylsulfanylpropenide)

The new high‐spin iron(II) complex, [Fe(C₁₂H₁₀N₆)₂(H₂O)₂](C₈H₃N₄S)₂ or [Fe(abpt)₂(H₂O)₂](tcnsme)₂ [where abpt is 4‐amino‐3,5‐di‐2‐pyridyl‐4H‐1,2,4‐triazole and tcnsme is the 1,1,3,3‐tetracyano‐2‐methylthiopropenide anion], consists of discrete [Fe(abpt)₂(H₂O)₂]²⁺ dications, where the Fe^II ion is coordinated by two N,N′‐bidentate chelating abpt ligands in the equatorial plane and two water molecules in trans positions, generating a distorted octahedral [FeN₄O₂] environment. The cationic unit is neutralized by two polynitrile tcnsme anions, in which the C—N, C—C and C—S bond lengths indicate extensive electronic delocalization. In the crystal structure, the dications and anions are linked through O—H...N and N—H...N hydrogen bonds involving the water H atoms and those of the NH₂ groups and the N atoms of the CN groups, leading to the formation of a three‐dimensional network.     

A photochromic dinuclear compound: aquatetrakis(μ‐2,3‐diphenylprop‐2‐enoato)bis(2,3‐diphenylprop‐2‐enoato)ethanolbis(1,10‐phenanthroline)dilanthanum(III)

The title dinuclear complex, (aqua‐1κO)tetrakis(μ‐2,3‐diphenylprop‐2‐enoato‐1:2κ²O:O′)bis(2,3‐diphenylprop‐2‐enoato)‐1κO;2κO‐(ethanol‐2κO)bis(1,10‐phenanthroline)‐1κ²N,N′;2κ²N,N′‐dilanthanum(III), [La₂(C₁₅H₁₁O₂)₆(C₁₂H₈N₂)₂(C₂H₅OH)(H₂O)], contains two similar La^III centres with distorted [LaO₆N₂] bicapped triganol–prismatic coordination polyhedra formed by six phenylcinnamate (PCA⁻ or 2,3‐diphenylprop‐2‐enoate) ligands, two 1,10‐phenanthroline (phen) ligands, a coordinating ethanol molecule and a coordinating water molecule. The two metal centres are bridged by four μ‐PCA⁻ ligands, with the remaining two PCA⁻ ligands coordinated in a monodentate fashion. The noncoordinated carboxylate O atoms on the terminal PCA⁻ ligands form O—H...O hydrogen bonds with the coordinated solvent molecules. Each La centre is also coordinated by a bidentate phen ligand. The PCA⁻ ligands all adopt syn–syn orientations, with the two phenyl rings presenting dihedral angles of about 70°. The compound displays photochromic behaviour both in solution and in the solid state.     

Reaction of iodo(trimethyl)silane with <Emphasis Type="Italic">N,N</Emphasis>-dimethyl carboxylic acid amides

The reactions of iodo(trimethyl)silane with N,N-dimethylformamide and N,N-dimethylacetamide Me₂NCOR (R = H, Me) at a molar ratio of 1: 2 involved mainly cleavage of the N-C(=O) bond with formation of up to 80% of N,N-dimethyltrimethylsilylamine Me₃SiNMe₂ and the corresponding acyl iodide RCOI. In the reaction with N,N-dimethylformamide, formyl iodide HCOI was detected for the first time by gas chromatography-mass spectrometry. The contribution of Me-N bond cleavage, leading to N-methyl-N-trimethylsilyl derivative Me(Me₃Si)NCOR and methyl iodide was considerably smaller. Another by-product was the corresponding N-methyl imide MeN(COR)₂ formed by reaction of the initial amide with acyl iodide. The primary intermediate in the reaction of iodo(trimethyl)silane with DMF and DMA is quaternary ammonium salt [Me₂(Me₃Si)N⁺COR] I⁻ which decomposes via dissociation of the N-CO and N-Me bonds.     

cis‐Bis(2,2′‐bipyridyl‐N,N′)dichlorosilicon diiodide

The crystal and molecular structure of the title compound, C₂₀H₁₆Cl₂N₄Si²⁺·2I^?, has been determined at 173 K. To our knowledge, this is the first crystal structure of a silicon tetrahalide complex with a bidentate base as a ligand. The two chloro ligands are cis relative to each other. The Si—N bonds trans to a chloro ligand are longer than the Si—N bonds trans to an Si—N bond. This feature is observed for the majority of M(bipy)₂Cl₂ (M = metal and bipy = 2,2′‐bipyridyl) complexes, but it does not hold for all structures retrieved from the Cambridge Structural Database. The two pyridyl rings of each bipyridyl unit are nearly coplanar, whereas the bipyridyl units are almost perpendicular to each other. The two I^? ions are more than 5 Å from the silicon centre. As a result, the compound can definitely be described as ionic. The crystal packing is stabilized by short C—H?I contacts.     

N,N′‐Dimethylpyrazinediium bis(tetrafluoroborate) and N,N′‐diethylpyrazinediium bis(tetrafluoroborate): new examples of anion–π triads

Crystallization of N,N′‐dimethylpyrazinediium bis(tetrafluoroborate), C₆H₁₀N₂²⁺·2BF₄⁻, (I), and N,N′‐diethylpyrazinediium bis(tetrafluoroborate), C₈H₁₄N₂²⁺·2BF₄⁻, (II), from dried acetonitrile under argon protection has permitted their single‐crystal studies. In both crystal structures, the pyrazinediium dications are located about an inversion center (located at the ring center) and each pyrazinediium aromatic ring is π‐bonded to two centrosymmetrically related BF₄⁻ anions. Strong anion–π interactions, as well as weak C—H...F hydrogen bonds, between BF₄⁻ and pyrazinediium ions are present in both salts.     

Self-Assembled Three-Dimensional Coordination Polymers with Unusual Ligand-Unsupported Ag−Ag Bonds: Syntheses,Structures, and Luminescent Properties

A staggered arrangement like that of the hydrogen atoms in ethane is exhibited by the six phenol groups about each pair of silver atoms in the self-assembled three-dimensional coordination networks [Ag₂(H₂L)₃]_nX_2n (H₂L=N,N′-bis(salicylidene)-1,4-diaminobutane; X⁻=NO₃⁻ or ClO₄⁻); the former is depicted (for clarity the H₂L ligands are represented by long rods and the Ag atoms by hatched circles). These solids contain short ligand-unsupported metal–metal bonds and display intense blue photoluminescence at room temperature.     

Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity

The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C₁₀H₆R₂N₂CH₂CH₂]²⁺ (R=H [1 a]²⁺ , Me [1 f]²⁺ , tBu [1 g]²⁺ ), and [C₁₂H₄R₄N₂CH₂CH₂]²⁺ (R=H [2 a]²⁺ , Me [2 b]²⁺ ) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]²⁺ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp³(C−F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF₃)₃C₆H₉. The dications are shown to act as hydride acceptors with the isolation of neutral species C₁₆H₁₄N₂ ( 3 a ) and C₁₆H₁₀Me₄N₂ ( 3 b ) and monocationic species [C₁₄H₁₃N₂]⁺ ( [4 a]⁺ ) and [C₁₈H₂₁N₂]+ ( [4 b]⁺ ). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.     

Structural Variances in the Homologous Series of Alkaline Earth Metallated Octamethylcyclotetrasilazandiides

The magnesium, calcium, and strontium metal derivatives of 2, 2, 4, 4, 6, 6, 8, 8‐octamethylcyclotetrasilazane (OMCTS) have been synthesized and structurally characterized by X‐ray diffraction studies. These are the first complexes of the homologous series of alkaline earth metalated OMCTS. Similar to the homologous series of the corresponding alkali metal complexes, the structural properties show remarkable tendencies in the series from magnesium to strontium. The magnesium dication causes the most pronounced deformation along the transannular N^‐···N^‐ vector of the [(c‐N‐SiMe₂‐NH‐SiMe₂‐)₂]^2‐ dianionic ring. The lengths of the Si‐N bonds are correlated to the bond types, so that shorter distances result when the bonds become more ionic. The difference between the long Si‐N(H) bonds and the short Si‐N^‐ bonds decreases gradually with the increasing mass of the alkaline earth metal dication.     

Di­chloro­bis­(tri­methyl­ene­thio­urea‐κS)antimony(III) chloride

In the title compound, [SbCl₂(C₄H₈N₂S)₂]Cl, the coordination around the Sb atom can be described as distorted pseudo‐octahedral. Both rings of the tri­methyl­ene­thio­urea ligands [alternatively 3,4,5,6‐tetrahydropyrimidine‐2(1H)‐thione] adopt an envel­ope conformation. The mol­ecules are connected into dimers in the ab plane by two intermolecular hydrogen bonds. The dimers are arranged into infinite one‐dimensional chains along the a axis as a result of the Cl^? ions forming intermolecular hydrogen bonds with three NH groups.