The New λ6Si‐Silicate Dianion [Si(NCO)6]2−: Synthesis and Structural Characterization of [K(18‐crown‐6)]2[Si(NCO)6]

The λ⁶Si‐silicate [K(18‐crown‐6)]₂[Si(NCO)₆] ( 10 ) was synthesized by treatment of Si(NCO)₄ with KNCO in the presence of 18‐crown‐6. Compound 10 (SiN₆ skeleton) is the first example of a hexa(cyanato‐N)silicate. It was characterized by solid‐state and solution NMR spectroscopy, and the acetonitrile solvate 10· 2CH₃CN was studied by single‐crystal X‐ray diffraction. To differentiate between the two isomeric [Si(NCO)₆]^2? and [Si(OCN)₆]^2? dianions, computational studies were performed.     

The Hexacyanodiborane(6) Dianion [B2(CN)6]2−

Diborane(6) dianions with substituents that are bonded to boron via carbon are very reactive and therefore only a few examples are known. Diborane(6) derivatives are the simplest catenated boron compounds with an electron‐precise B–B σ‐bond that are of fundamental interest and of relevance for material applications. The homoleptic hexacyanodiborane(6) dianion [B₂(CN)₆]²⁻ that is chemically very robust is reported. The dianion is air‐stable and resistant against boiling water and anhydrous hydrogen fluoride. Its salts are thermally highly stable, for example, decomposition of (H₃O)₂[B₂(CN)₆] starts at 200 °C. The [B₂(CN)₆]²⁻ dianion is readily accessible starting from 1) B(CN)₃²⁻ and an oxidant, 2) [BF(CN)₃]⁻ and a reductant, or 3) by the reaction of B(CN)₃²⁻ with [BHal(CN)₃]⁻ (Hal=F, Br). The latter reaction was found to proceed via a triply negatively charged transition state according to an S_N2 mechanism.     

Synthese und Kristallstrukturen von (2‐Methylpyridinium)3[TbCl6] und (2‐Methylpyridinium)2[TbCl5(1‐Butanol)]

Preparation and Structure of (2‐Methylpyridinium)₃[TbCl₆] and (2‐Methylpyridinium)₂[TbCl₅(1‐Butanol)] The complex chlorides (2‐Methylpyridinium)₃[TbCl₆] (1) and (2‐Methylpyridinium)₂[TbCl₅(1‐Butanol)] (2) have been prepared for the first time. The crystal structures have been determinated from single crystal X‐ray diffraction data. 1 crystallizes in the monoclinic space group C2/c (Z = 8) with a = 3241,2(5) pm, b = 897,41(9) pm, c = 1774,2(2) pm and β = 97,83(2)°, 2 in the monoclinic space group P2₁/n (Z = 4) with a = 1372,96(16) pm, b = 997,57(9) pm, c = 1820,5(2) pm and β = 108,75(1)°. The structures contain isolated octahedral building units [TbCl₆]^3– and [TbCl₅(1‐Butanol)]^2–, respectively.     

Cyclische Polyselenidoarsenate(III) und -antimonate(III): PPh4[Se5AsSe], PPh4[AsSe6–xSx], (PPh4)2[As2Se6] · 2 CH3CN und (PPh4)2[Se6SbSe]2

Cyclic Polyselenidoarsenates(III) and Polyselenidoantimonates(III): PPh₄[Se₅AsSe], PPh₄[AsSe_6–xS _x ], (PPh₄)₂[As₂Se₆] · 2 CH₃CN, and (PPh₄)₂[Se₆SbSe]₂ In acetonitrile, AsCl₃ and sodiumphenolate formed Cl₂AsOPh which then was reacted with PPh₄Se₅ and finally with Na₂Se to yield PPh₄[Se₅AsSe]. With Na₂S instead of Na₂Se, PPh₄[AsSe_6–xS_x] was obtained; the sulfur contents increased with increasing reaction temperature and time (x = 0.21 to 1.09). With PPh₄Se₂ instead of PPh₄Se₅, (PPh₄)₂[1,4-As₂Se₆] · 2 CH₃CN and PPh₄[Se₅AsSe] were the products. With SbCl₃ instead of AsCl₃, (PPh₄)₂[Se₆SbSe]₂ formed. PPh₄[Se₅AsSe] can also be produced from As₂Se₃, PPh₄Br, Na₂Se and selenium in acetonitrile. The crystal structure of PPh₄[SeAsSe₅] is isotypic with PPh₄[S₅AsS] (X-ray structure analysis with 2414 observed reflexions, R = 0.038). The Se₅AsSe^– ion consists of a six-membered AsSe₅ ring in chair conformation, and the As atom has an additional terminal Se atom. The compounds PPh₄[AsSe_6–xS_x] have the same crystal structures, with sulfur atoms taking all selenium positions at random, but with a preference for the terminal position. The anion in (PPh₄)₂[As₂Se₆] · 2 CH₃CN also has a six-membered ring structure in chair conformation, with two arsenic atoms in positions 1 and 4. The centrosymmetric anion in (PPh₄)₂[Se₆SbSe]₂ consists of a central Sb₂Se₂ ring, and a Se₆ ligand is bonded in a chelating manner to each Sb atom (X-ray structure analysis with 2669 observed reflexions, R = 0.099). ⁷⁷Se-NMR spectra are reported.     

Die Kristallstrukturen der Hexachlorometallate NH4[SbCl6], NH4[WCl6], [K(18‐Krone‐6)(CH2Cl2)]2[WCl6]·6CH2Cl2 und (PPh4)2[WCl6]·4CH3CN

Crystal Structures of the Hexachlorometalates NH₄[SbCl₆], NH₄[WCl₆], [K(18‐crown‐6)(CH₂Cl₂)]₂[WCl₆]·6CH₂Cl₂ and (PPh₄)₂[WCl₆]·4CH₃CN The crystal structures of the title compounds were determined by single crystal X‐ray methods. NH₄[SbCl₆] and NH₄[WCl₆] crystallize isotypically in the space group C2/c with four formula units per unit cell. The NH₄⁺ ions occupy a twofold crystallographic axis, whereas the metal atoms of the [MCl₆]^— ions occupy a centre of inversion. There exist weak interionic hydrogen bridges. [K(18‐crown‐6)(CH₂Cl₂)]₂[WCl₆]·6CH₂Cl₂ crystallizes in the orthorhombic space group R3¯/m with Z = 3. The compound forms centrosymmetric ion triples, in which the potassium ions are coordinated with a WCl₃ face each. In trans‐position to it the chlorine atom of a CH₂Cl₂ molecule is coordinated so that, together with the oxygen atoms of the crown ether, coordination number 10 is achieved. (PPh₄)₂[WCl₆]·4CH₃CN crystallizes in the monoclinic space group P2₁/c with Z = 4. This compound, too, forms centrosymmetric ion triples, in which in addition the acetonitrile molecules are connected with the [WCl₆]^2— ion via weak C—H···Cl contacts.     

Darstellung,Kristallstrukturen und Schwingungsspektren von [Pt(N3)6]2– und [Pt(N3)Cl5]2–, 195Pt‐ und 15N‐NMR‐Spektren von [Pt(N3)nCl6–n]2– und [Pt(15NN2)n(N215N)6–n]2–, n = 0–6

Synthesis, Crystal Structures, and Vibrational Spectra of [Pt(N₃)₆]^2– and [Pt(N₃)Cl₅]^2–, ¹⁹⁵Pt and ¹⁵N NMR Spectra of [Pt(N₃)_nCl_6–n]^2– and [Pt(¹⁵NN₂)_n(N₂¹⁵N)_6–n]^2–, n = 0–6 By ligand exchange of [PtCl₆]^2– with sodium azide mixed complexes of the series [Pt(N₃)_nCl_6–n]^2– and with ¹⁵N‐labelled sodium azide (Na¹⁵NN₂) mixtures of the isotopomeres [Pt(¹⁵NN₂)_n(N₂¹⁵N)_6–n]^2–, n = 0–6 and the pair [Pt(¹⁵NN₂)Cl₅]^2–/[Pt(N₂¹⁵N)Cl₅]^2– are formed. X‐ray structure determinations on single crystals of (Ph₄P)₂[Pt(N₃)₆] ( 1 ) (triclinic, space group P1, a = 10.175(1), b = 10.516(1), c = 12.380(2) Å, α = 87.822(9), β = 73.822(9), γ = 67.987(8)°, Z = 1) and (Ph₄As)₂[Pt(N₃)Cl₅] · HCON(CH₃)₂ ( 2 ) (triclinic, space group P1, a = 10.068(2), b = 11.001(2), c = 23.658(5) Å, α = 101.196(14), β = 93.977(15), γ = 101.484(13)°, Z = 2) have been performed. The bond lengths are Pt–N = 2.088 ( 1 ), 2.105 ( 2 ) and Pt–Cl = 2.318 Å ( 2 ). The approximate linear azido ligands with N^α–N^β–N^γ‐angles = 173.5–174.6° are bonded with Pt–N^α–N^β‐angles = 116.4–121.0°. In the vibrational spectra the PtCl stretching vibrations of (n‐Bu₄N)₂[Pt(N₃)Cl₅] are observed at 318–345, the PtN stretching modes of (n‐Bu₄N)₂[Pt(N₃)₆] at 401–428 and of (n‐Bu₄N)₂[Pt(N₃)Cl₅] at 408–413 cm^–1. The mixtures (n‐Bu₄N)₂[Pt(¹⁵NN₂)_n(N₂¹⁵N)_6–n], n = 0–6 and (n‐Bu₄N)₂[Pt(¹⁵NN₂)Cl₅]/(n‐Bu₄N)₂[Pt(N₂¹⁵N)Cl₅] exhibit ¹⁵N‐isotopic shifts up to 20 cm^–1. Based on the molecular parameters of the X‐ray determinations the vibrational spectra are assigned by normal coordinate analysis. The average valence force constants are f_d(PtCl) = 1.93, f_d(PtN^α) = 2.38 and f_d(N^αN^β, N^βN^γ) = 12.39 mdyn/Å. In the ¹⁹⁵Pt NMR spectrum of [Pt(N₃)_nCl_6–n]^2–, n = 0–6 downfield shifts with the increasing number of azido ligands are observed in the range 4766–5067 ppm. The ¹⁵N NMR spectrum of (n‐Bu₄N)₂[Pt(¹⁵NN₂)_n(N₂¹⁵N)_6–n], n = 0–6 exhibits by ¹⁵N–¹⁹⁵Pt coupling a pseudotriplett at –307.5 ppm. Due to the isotopomeres n = 0–5 for terminal ¹⁵N six well‐resolved signals with distances of 0.03 ppm are observed in the low field region at –201 to –199 ppm.     

Über die Kristallstrukturen der Cyanokomplexe [Co(NH3)6][Fe(CN)6], [Co(NH3)6]2[Ni(CN)4]3 · 2 H2O und [Cu(en)2][Ni(CN)4]

On the Crystal Structures of the Cyano Complexes [Co(NH₃)₆][Fe(CN)₆], [Co(NH₃)₆]₂[Ni(CN)₄]₃ · 2 H₂O, and [Cu(en)₂][Ni(CN)₄] Of the three title compounds X‐ray structure determinations were performed with single crystals. [Co(NH₃)₆][Fe(CN)₆] (a = 1098.6(6), c = 1084.6(6) pm, R3, Z = 3) crystallizes with the CsCl‐like [Co(NH₃)₆][Co(CN)₆] type structure. [Co(NH₃)₆]₂[Ni(CN)₄]₃ · 2 H₂O (a = 805.7(5), b = 855.7(5), c = 1205.3(7) pm, α = 86.32(3), β = 100.13(3), γ = 90.54(3)°, P1, Z = 1) exhibits a related cation lattice, the one cavity of which is occupied by one anion and 2 H₂O, whereas the other contains two anions parallel to each other with distance Ni…Ni: 423,3 pm. For [Cu(en)₂][Ni(CN)₄] (a = 650.5(3), b = 729.0(3), c = 796.5(4) pm, α = 106.67(2), β = 91.46(3), γ = 106.96(2)°, P1, Z = 1) the results of a structure determination published earlier have been confirmed. The compound is weakly paramagnetic and obeys the Curie‐Weiss law in the range T < 100 K. The distances within the complex ions of the compounds investigated (Co–N: 195.7 and 196.4 pm, Ni–C: 186.4 and 186.9 pm, resp.) and their hydrogen bridge relations are discussed.     

Synthesis and thermal decomposition reaction kinetics of complexes of [Sm2(m‐ClBA)6(phen)2] · 2H2O and [Sm2(m‐BrBA)6(phen)2] · 2H2O

Complexes of [Sm₂(m‐ClBA)₆(phen)₂] · 2H₂O and [Sm₂(m‐BrBA)₆(phen)₂] · 2H₂O (m‐ClBA = m‐chlorobenzoate, m‐BrBA = m‐bromobenzoate, and phen = 1,10‐phenanthroline) were prepared and characterized by elemental analysis and IR spectra. The thermal decomposition processes of the two complexes were studied by means of TG–DTG and IR techniques. Their thermal decomposition kinetics were investigated from the analysis of the TG and DTG curves by jointly using a new method proposed by us and a newly nonlinear isoconversional integral method. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 39: 67–74, 2007     

Synthesis and characterization of novel chelated dimethylamino lithium alkoxides: molecular structures of [1‐LiOC(C6H11)2‐2‐NMe2C6H4]2 and [1‐LiOCPh2CH2‐2‐NMe2C6H4]2

From the reaction of 1‐HOCPh₂‐2‐NMe₂C₆H₄ ( 1 ), 1‐HOC(C₆H₁₁)₂‐2‐NMe₂C₆H₄ ( 2 ) and 1‐HOCPh₂CH₂‐2‐NMe₂C₆H₄ ( 3 ) with n‐BuLi in diethyl ether, the solvent‐free chelated dimethylamino lithium alkoxides [1‐LiOCPh₂‐2‐NMe₂C₆H₄]₂ ( 4 ), [1‐LiOC(C₆H₁₁)₂‐2‐NMe₂C₆H₄]₂ ( 5 ) and [1‐LiOCPh₂CH₂‐2‐NMe₂C₆H₄]₂ ( 6 ) were obtained. The lithium alkoxides 4 – 6 were characterized by ¹H, ⁷Li, and ¹³C NMR spectroscopy. Crystal structure determinations of 5 and 6 were carried out. Compounds 5 and 6 are examples of structurally characterized solvent‐free chelated dimethylamino lithium alkoxides and 6 is a rare example of this type containing a seven‐membered ring. Copyright © 2002 John Wiley & Sons, Ltd.     

195Pt-NMR-spektroskopischer Nachweis gemischter Hexahalogenodiplatinate(II), [Pt2ClnBr6 − n]2−, n = 0 – 6

¹⁹⁵Pt NMR Spectroscopic Evidence of Mixed Hexahalogenodiplatinates(II), [Pt₂Cl_nBr_{6 ? n}]^2?, n = 0 – 6 The complete system of the mixed complex ions [¹⁹⁵Pt₂Cl_nBr_{6 – n}]^2?, n = 0 – 6, is formed by stirring a suspension of the tetrabutylammonium salt(TBA)₂[¹⁹⁵PtCl₄] in an aqueous solution of KBr at 80°C. The mixture recrystallized from acetone/diethyl ether contains the 24 possible species, 12 with two equivalent ¹⁹⁵Pt atoms resulting in 12 singlets and 12 with inequivalent ¹⁹⁵Pt atoms resulting in 24 dublets. The expected 60 signals are really observed in the high resolution 1D-¹⁹⁵Pt-nmr spectrum. Using characteristic increments of chemical shifts, differentiating ²J(¹⁹⁵Pt ? ¹⁹⁵Pt) coupling constants and a 2D-¹⁹⁵Pt/¹⁹⁵Pt-COSY spectrum the complete and unambiguous assignment of all resonances is achieved. The presence of all components including the geometric isomers and their distribution derived from measured intensities reveal the statistical formation.