Transmetallation of Bis(6-diphenylphosphinoacenaphth-5-yl)-Mercury and -Tributyltin with Precious Metal Chlorides

The reaction of bis(6-diphenylphosphinoacenapht-5yl)mercury, (6-Ph₂P-Ace-5-)₂Hg, with [(CO)₂RhCl]₂ and PtCl₂ proceeded with extrusion of mercury / mercury(I) chloride and provided the octahedral rhodium and platinum complexes (6-Ph₂P-Ace-5-)₂Rh(CO)Cl and (6-Ph₂P-Ace-5-)₂PtCl₂, respectively. The reaction of the (6-diphenylphosphinoacenapht-5yl)stannane 6-Ph₂P-Ace-5-SnBu₃ with PdCl₂ gave rise to tributyltin chloride and a dimeric arylpalladium chloride [(6-Ph₂P-Ace-5-)PdCl]₂ with a planar Pd₂Cl₂ core. Together with the previously known gold(III) complex cis- and trans-[R₂Au][Cl], the newly prepared compounds were investigated by DFT calculations. The fully optimized gas-phase structure of [(6-Ph₂P-Ace-5-)PdCl]₂ gives rise to a bend Pd₂Cl₂ core featuring a Pd ··· Pd palladophilic interaction. The bonding situation was studied using a set of real-space bonding indicators (RSBIs) derived from the methods Atoms-In-Molecules (AIM), Electron Localizability Indicator (ELI-D) and Non-Covalent Interaction (NCI) index.     

Local limit theorems for transition densities of Markov chains converging to diffusions

We consider triangular arrays of Markov chains that converge weakly to a diffusion process. Local limit theorems for transition densities are proved. Received: 28 August 1998 / Revised version: 6 September 1999 / Published online: 14 June 2000     

Über das Donor‐Verhalten von Bis(pyrazolyl)‐Schwefel‐Derivaten

The Donor Properties of Bis(pyrazolyl)‐Sulfur Derivatives From the reactions of bis(pyrazolyl)sulfane S(pz)₂ ( 1 ) with the fluoro Lewis acids BF₃ and AsF₅ in liquid SO₂ the 1:2‐adducts S(pz·BF₃)₂ ( 2 ) and S(pz·AsF₅)₂ ( 3 ) are obtained. 1 reacts with [Co(SO₂)₄(FAsF₅)₂] to give the doubly bridged FAsF₄F dimeric complex [Co{S(pz)₂}(FAsF₅)(SO₂)(μ‐FAsF₄F)]₂ ( 5 ). From F₂S(pz)₂ and [Ni(SO₂)₆](AsF₆)₂, the fluorocubane [Ni₄F₄{S(pz)₂}₄(μ‐FAsF₄F)₂](AsF₆)₂·4SO₂ ( 8 ) is isolated. The X‐ray structures of the compounds 2 , 3 , 5 and 8 are reported.     

Versuche zur Darstellung von t‐BuCN5S3 und die unerwartete Isolierung einer kovalenten Modifikation von Tetraschwefelpentastickstoff‐chlorid S4N5Cl

Attempts to prepare t‐BuCN₅S₃ and the unexpected Isolation of a covalent Modification of Tetrasulfur‐pentanitrogen Chloride S₄N₅Cl Attempts to prepare the bicyclic sulfur‐nitrogen heterocycle t‐BuCN₅S₃ via (NSCl)₃ and the corresponding silylated amidinates and amidines failed because of the inaccessibility of the silylated intermediates. Reactions of MN(SiMe₃)₂ (M = Li, Na) with t‐BuCN did not yield the expected amidinates t‐BuC(NSiMe₃)₂M, instead the adducts [t‐BuCN·MN(SiMe₃)₂]₂ were isolated. The attempted synthesis of t‐BuCN₅S₃ from t‐BuCN(SiMe₃)₂M, prepared in situ from t‐BuLi and Me₃SiNCNSiMe₃, and (NSCl)₃ unexpectedly resulted a mixture of S₄N₅Cl and S₅N₆. The crystal structure determination for S₄N₅Cl showed a new covalent modification of S₄N₅Cl (monoclinic, P2₁/c, a = 1005.0(4) pm, b = 1193.5(8) pm, c = 1152.5(6) pm, β = 93.67(3)°), different from the known ionic S₄N₅Cl (orthorhombic, Pnma, a = 1738.90(10) pm, b = 781.50(10) pm, c = 483.03(5)). The unsuccessful attempts to prepare t‐BuCN₅S₃, the unexpected formation of S₄N₅Cl and S₅N₆, and the bonding properties of the new covalent modification of S₄N₅Cl are discussed.     

Syntheses and chemistry of hypervalent cyclo-R4Sb4, cyclo-(RSbE)n[R = 2-(Me2NCH2)C6H4, E = O, S] and precursors

The cyclostibane R(4)Sb(4)(1)(R = 2-(Me(2)NCH(2))C(6)H(4)) was synthesized by reduction of RSbCl(2) with Mg in THF or with Na in liquid NH(3). The reaction of 1 with [W(CO)(5)(THF)] gives the stibinidene complex RSb[W(CO)(5)](2)(2). RSbCl(2) and (RSbCl)(2)E [E = O (6), E = S (8)] react with KOH or Na(2)S in toluene/water to give the heterocycles (RSbE)(n)[E = O, n= 3 (3); E = S, n= 2 (4)]. The chalcogeno-bridged compounds of the type (RSbCl)(2)E [E = O (6), E = S (8)] were synthesized by reaction of RSbCl(2) with KOH or Na(2)S in toluene/water, but also by reaction of RSbCl(2) with the heterocycles (RSbE)(n). The compounds (RSbI)(2)O (7) and (RSbBr)(2)S (9) were prepared via halogen-exchange reactions between (RSbCl)(2)E and NaI (E = O) or KBr (E = S) or by reactions between RSbI(2) and KOH or RSbBr(2) and Na(2)S. The reaction of cyclo-(RSbS)(2) with W(CO)(5)(THF) in THF results in trapping of the cis isomer in cyclo-(RSbS)(2)[W(CO)(5)](5). The solution behaviour of the compounds was investigated by (1)H and (13)C NMR spectroscopy. The molecular structures of compounds 1-7 and 9 were determined by single-crystal X-ray diffraction.     

Hexaalkylguanidinium and 2-(dialkylamino)-1,3-dimethylimidazolinium trimethyldifluorosiliconates and perfluoroalkoxides. Accidental isolation and molecular structure of [C(NMe2)3]+F-*6CH2Cl2

Hexaalkylguanidinium and 2-(dialkylamino)-1,3-dimethylimidazolinium trimethyldifluorosiliconates, precursors for two stable hexaalkylguanidinium perfluoroalkoxides, were synthesized by treating commercially available bis(dialkylamino)difluoromethane derivatives with (dialkylamino)trimethylsilanes in aprotic media. With hexamethylguanidinium pentafluoroethoxide the introduction of the lipophilic and electronegative C2F5O group was straightforwardly achieved in the case of primary and secondary alkyl triflates to furnish the respective fluorinated ethers. The molecular structures of [(CH2NMe)2C(NEt2)]+[Me3SiF2]- and [C(NMe2)3]+F-*6CH2Cl2 were determined, showing in the latter case a fluoride anion octahedrally coordinated by six methylene chloride molecules via hydrogen bridges with a F...H distance of 205 pm (C...F distance 270.0(3) pm).     

A novel type of formation of zwitterionic compounds,containing two phosphorus atoms of opposite charge and different coordination number

The oxidation of bis[bis(dialkylamino)phosphinyl]methane 1 with 5,5,5-trifluoro-4-(trifluoromethyl)penta-3-en-2-one 2 unexpectedly gave zwitterionic compound 7 which according to X-ray analysis contains two phosphorus atoms of opposite charge and different coordination number (lambda 4P(+); lambda 6P(-)) with a direct P-H bond at the hexacordinated phosphorus.     

2‐Polyfluoroacylcycloalkanones in reactions with selected phosphorus(III) compounds

The reactivity of 2‐polyfluoroacylcycloalkanones and their O‐silylated derivatives towards phosphites and tris(trimethylsilyl)aminoiminophosphine has been investigated. From α‐polyfluoroalkyl substituted phosphonates, generated from tris(trimethylsilyl) phosphite and 1,3‐diketones, the respective phosphonic acids and their salts have been obtained. In one case, upon warming, a phosphonic acid underwent a ring closure to yield an oxaphospholene. 2‐Trifluoroacetylcycloalkanones and diethyl isocyanatophosphite furnished phosphoranes diastereospecifically, via addition of phosphorus at the trifluoroacetyl group and two additional heterocyclizations. Tris(trimethylsilyl)aminoiminophosphine formed very reactive trimethylsilylimino‐1,2λ⁵σ⁴‐phospholenes, which added hexafluoroacetone to give spirocyclic 1,3,2λ⁵σ⁵‐oxazaphosphetanes. The structures of the new compounds were determined by NMR spectroscopy and X‐ray single crystal analysis. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:97–107, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10001