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Reaction of the cesium antimonide complex [Cs(18C6)2][SbH2] (1, 18C6 = 18-crown-6 ether) with the triamidoamine actinide separated ion pairs [An(TrenTIPS)(L)][BPh4] (TrenTIPS= {N(CH2CH2NSiiPr3)3}3–; An/L = Th/DME (2Th); U/THF (2U)) affords the triactinide undeca-antimontriide Zintl clusters [{An(TrenTIPS)}3(μ3-Sb11)] (An = Th (3Th), U (3U)) by dehydrocoupling. Clusters 3Thand 3Uprovide two new examples of the Sb113–Zintl trianion and are unprecedented examples of molecular Sb113–being coordinated to anything since all previous reports featured isolated Sb113–Zintl trianions in separated ion quadruple formulations with noncoordinating cations. Quantum chemical calculations describe dominant ionic An–Sb interactions in 3Thand 3U, though the data suggest that the latter exhibits slightly more covalent An–Sb linkages than the former. Complexes 3Thand 3Uhave been characterized by single crystal X-ray diffraction, NMR, IR, and UV/vis/NIR spectroscopies, elemental analysis, and quantum chemical calculations.

There is continued burgeoning interest in metal–metal multiple bonding to further our understanding of chemical bonding across the periodic table. However, although polar covalent metal–metal multiple bonding is well known for the dand pblocks, it is relatively underdeveloped for actinides. Homometallic examples are found in spectroscopic or fullerene-confined species, and heterometallic variants exhibiting a polar covalent σbond supplemented by up to two dative πbonds are more prevalent. Hence, securing polar covalent actinide double and triple metal–metal bonds under normal experimental conditions has been a fundamental target. Here we exploit the protonolysis and dehydrocoupling chemistry of the parent dihydrogen-antimonide anion, to report one-, two- and three-fold thorium–antimony bonds, thus introducing polar covalent actinide–metal multiple bonding under normal experimental conditions between some of the heaviest ions in the periodic table with little or no bulky-substituent protection at the antimony centre. This provides fundamental insights into heavy element multiple bonding, in particular the tension between orbital-energy-driven and overlap-driven covalency for the actinides in a relativistic regime.

The synthesis of a second beryllium bromide modification, β-BeBr2, was accomplished through recrystallization of α-BeBr2from benzene in the presence of cyclo-decamethylpentasiloxane. This phase was analyzed via single-crystal X-ray diffraction and IR and Raman spectroscopy as well as density functional theory calculations. This enabled a comparison to α-BeBr2and the α and β phases of beryllium chloride and iodide.

Lewis acid–base adducts between potassium bis(trimethylsilyl)pnictogenides [KPn(SiMe3)2](Pn = Sb and Bi) and trimethyltriels (EMe3(E = Al, Ga, In) were synthesized and crystallized using 18-crown-6 as ligand for the potassium ions. In the course of these investigations, we were able to fully characterize a row of compounds of the type [K(18c6)(thf)0–2][Pn(SiMe3)2(EMe3)n] (n= 1, 2) with a different amount of Lewis acids bonding to the group 15 element. Moreover, we investigated the influence of the steric demand of the Lewis acids through the use of GaEt3and GatBu3. All isolated compounds were examined by NMR spectroscopy, IR spectroscopy, elemental analysis and X-ray structure analysis. The obtained adducts of negatively charged [Pn(SiMe3)2]−fragments with Lewis acids represent a new class of compounds, which illustrate the HSAB concept and show the different extents of the inert pair effect between antimony and bismuth. In particular, the dative bonds between the higher homologues of both main groups have so far been underdeveloped in research.

The ultrafast fluorescence quenching of 2,6-sulfanyl-core-substituted naphthalenediimides was investigated by transient spectroscopy. We find a strong dependence of the relaxation on the chemical structure of the substituent. Direct linking of an aryl rest to the sulfur atom leads to a strong red shift of the fluorescence in 1 ps and the disappearance of the emission in 5−7 ps depending on the polarity and viscosity of the solvent. This complex behavior is interpreted with the help of quantum chemical calculations. The calculations suggest that the initial relaxation corresponds to a planarization of the substituents and an associated partial electron transfer. This is followed by a twisting of the phenylsulfanyl substituents out of the molecular plane that allows a complete localization of the electron-donating orbital on the aryl group. Finally the back transfer happens in another 5−7 ps. For an additional methylene spacer group between the sulfur and the aryl, this sequence of relaxation steps is not possible and a simple exponential decay, slower by about 1 order of magnitude, is found.

We present the coordination chemistry of the cyclodimethylsiloxanes D6and D7toward alkaline earth metal salts. The coordination chemistry of these macrocycles toward alkaline earth metals has been unprecedented to date, and we could show that these ligands coordinate better than previously thought. Direct reaction of alkaline earth metal salts with these ligands yields stable complexes even with a relatively strongly coordinating iodide anion. A handful of counterintuitive coordination compounds could be characterized by single-crystal X-ray diffraction analysis. Quantum chemical calculations of suited Born–Haber cycles showed that these complexes are indeed stable, for Mg2+and Ca2+even with iodide employed as the anion and for Sr2+and Ba2+in the presence of GaI3.

III–V semiconductors containing small amounts of nitrogen (“dilute nitrides”) are very promising material systems for optoelectronic applications. Devices based on dilute nitrides currently suffer from problematic C incorporation. To overcome this problem, a novel nitrogen (N) and arsenic (As) precursor for metal–organic vapor phase epitaxy (MOVPE) of the dilute nitride di-tert-butylaminoarsane (DTBAA) has been introduced. DTBAA in comparison to the commonly used 1,1-dimethylhydrazine (UDMHy) showed a significantly improved N incorporation efficiency. The molecule exhibits no strong carbon (C)–N bond, and the C is only present in large alkyl groups which form fewer C radicals since β-H elimination is the dominating decomposition process. This should significantly lower the problematic C incorporation in dilute nitrides and lead to highly efficient devices. To understand the high N incorporation efficiency as well as the As incorporation, the gas-phase decomposition of this novel precursor has been studied with a real time Fourier transform (FT) quadrupole ion trap mass spectrometer (iTrap) from Carl Zeiss SMT GmbH in a horizontal Aixtron Aix 200 GFR MOVPE reactor. Formation of isobutane and isobutene proves a radical cleavage and β-H-elimination as decomposition processes of the tert-butyl groups attached to the molecule. Furthermore, the appearance of ammonia (NH3) has been detected. This indicates a direct cleavage of the As–N bond of the molecule, resulting in the formation of an aminyl radical (NH2•). The formation of NH2•explains the high N incorporation efficiency of DTBAA as well as its limitations due to desorption of NH3at higher temperatures.

Herein we present the synthesis and coordination chemistry of the partially silicon based crown ether analogues 1,2,4,5-tetrasila-benzo[15]crown-5 (1) and 1,2,4,5-tetrasila[18]crown-6 (7). Stable complexes of alkali and alkaline earth metal iodides could be obtained showing the good coordination ability of these ligands. The complexes [MA(1,2,4,5-tetrasila-benzo[15]crown-5)I] (MA= Li+(2), Na+(4)) and [MEA(1,2,4,5-tetrasila-benzo[15]crown-5)I2] (MEA= Mg2+(3), Ca2+(5), Sr2+(6)) were obtained by equimolar reaction of 1with the respective alkali or alkaline earth metal iodide. Depending on the ionic radii of the respective cations, the coordination modes of the siloxane backbone are significantly different and could be well-represented by means of 29Si NMR spectroscopy. In addition, we were able to generate the unusual dinuclear complex [Ba2(1,2,4,5-tetrasila[18]crown-6)2I4] (8) by reaction of 7with BaI2. All compounds were characterized via single crystal X-ray diffraction (XRD) analysis.

Within this study, the synthesis and coordination chemistry of open-chain ligands bearing disila-units is presented. Instead of basic 1:1 complexes, structural diversity was discovered in the variety of ligand and salt. Stable complexes of alkali and alkaline earth metal complexes were obtained by equimolar reactions of different salts with the disila-bridged podands 8,9-disila-EO5 (1) and 11,12-disila-EO7 (2) (EO5 = pentaethylene glycol; EO7 = heptaethylene glycol). The respective alkaline earth metal complexes of the type [Ca(8,9-disila-EO5)(OTf)2] (3), [Sr(8,9-disila-EO5)I2] (5), [Sr(11,12-disila-EO7)I]I (6), and [Ba(11,12-disila-EO7)OTf2] (7) (OTf = CF3SO3–) were characterized via single-crystal X-ray diffraction analyses. Within the reaction of the alkali metal salt NaPF6with 1, the sodium ion acts as a template during the complexation process. Under elimination of one molecule of diethylene glycol, the dinuclear species [Na2(8,9,17,18-tetrasila-EO8)(PF6)2]·EO2 (4) (EO8 = octaethylen glycol, EO2 = diethylene glycol) is obtained, in which the sodium cations are 7-fold coordinated within a disilane-bearing framework. The reaction of 2with CsOTf failed, leading to recrystallization of anhydrous CsOTf. By means of DFT calculations it was shown that the disila-bearing ligands are burdened with negative hyperconjugation interactions between the silicon and the oxygen atoms, but the coordination by sufficiently hard cations can easily overcompensate the competing polarization. In contrast, soft Lewis acids barely share interactions with silicon-bonded oxygen atoms. All findings are consistent with observations made in solution according to 29Si NMR spectroscopical studies.

Two new hybrid ligands that exhibit organic as well as siloxane chains between four phosphorus atoms in bridge‐head positions were synthesized. These species show a very different ability with regard to the formation of coordination compounds. Whereas compound 1with the short (C2H4)2O ether units shows no ability to act as a ligand, the compound with the longer (C2H4O)2C2H4chains between the siloxane fragments could be obtained as the free ligand and with incorporated Li2I2and Ag2I2units. The observed coordination modi of the lithium and silver ions in these complexes corresponds to the HSAB‐ or Pearson concept. The silver ions prefer the soft phosphorus atoms as a bonding partner, while, for lithium, coordination by the hard oxygen atoms is favoured.

In this work we report the synthesis and characterisation of the 1.5‐diphosphanyldiethylether O{C2H4PH(SiiPr3)}2(2) in which two silyl‐substituted phosphine groups are linked by an ether bridge as well as the compound O(SiiPr2PHEt)2(3) where two ethyl substitute phosphine groups are connected by a siloxane bridge. In addition, we describe the metalation of 2and 3with triisopropylindium. These reactions lead to the compounds [O{C2H4P(SiiPr3)IniPr2}2] (4) and [O{SiiPr2P(Et)IniPr2}2] (5) with In2P2ring structures.

The heterocubane‐like molecules [tBu2PhSiESn]4(E = P (2), As (3)) and [(Me3Si)3SiPM]4(M= Sn (4), Pb (5)) were obtained by the reaction of primary silyl phosphines or ‐arsines with M{N(SiMe3)2}2. Likewise, the reactions of the miscellaneously substituted arsine (Me3Si)3SiAs(SiMe3)2(1) with MCl2yielded the heterocubane species [(Me3Si)3SiAsM]4(M= Sn (8), Pb (9)). The unique cage compounds [(tBu2PhSiAs)4Sn3LiOEt2]–[Li(Et2O)4]+(6) and [(tBu2PhSiAsSn)4SnCl(Bu)]4(7) could be obtained in a metathesis reaction of SnCl2with the lithiated silylarsine tBu2PhSiAsLi2in different stoichiometric percentages.

The synthesis of siloxane‐bridged P2and P4compounds can be achieved through metalation of primary or cyclic diphosphanylsiloxane compounds and subsequent oxidative coupling using C2H4Br2as reagent. Starting from the cyclic diphosphanylsiloxane [O(iPr2Si)2PH]2, the reaction with the silazanides of the earth alkaline metals leads to the metalated compounds [M(DME)2{O(iPr2Si)2P}2] (1: M = Ca, 2: M = Sr, 3: M = Ba). Subsequent oxidation yields the bicyclic species P2[O(iPr2Si)2]2(4). In an analogous reaction sequence with the primary diphosphanylsiloxane O(iPr2Si)2PH2the cyclic diphosphane O(iPr2SiPH)2(5) could be obtained and was successfully used for the same reaction pathway, leading to the corresponding metalated compound 6. Further oxidative coupling resulted in an intermolecular P–P bond formation, yielding the cage compound P4[O(iPr2Si)2]2(7).

The reaction of iPr2Si(PH2)2(1) with [Ca{N(SiMe3)2}2(THF)2] at 25 °C in molar ratio 1:1 yields the compound [Ca3{iPr2Si(PH)2}3(THF)6] (2). Compound 2consists of two Ca2P3trigonal bipyramids with one conjoint calcium corner and SiiPr2bridged phosphorus atoms. In contrast, the same reaction at 60 °C yield the complex [Ca({P(SiiPr2)2PH}2(THF)4] (3). The isotype strontium compound [Sr({P(SiiPr2)2PH}2(THF)4] (4) was obtained from the reaction of iPr2Si(PH2)2with [Sr{N(SiMe3)2}2(DME)2]. The Compounds 2–4were characterised by single crystal X‐ray diffraction, elemental analysis as well as IR and NMR spectroscopic techniques.

Alkaline earth metal derivatives of the diphosphanyldisiloxane OSiiPr2PH221 were obtained by reactions of 1with MgBu2and MNSiMe322M = Ca, Sr, Ba, respectively. The metal complexes formed were characterised by elemental analysis, NMR spectroscopy, and IR spectroscopy as well as by singlecrystal structure analysis. The solidstate structures depend on the metal ion involved. The magnesium derivative crystallizes from thf as a trimer and exhibits a sixmembered Mg3P3ring. In contrast, the Ca und Sr derivatives show a dimeric structure via formation of M2P2rings M = Ca, Sr. Eventually, the Ba derivative forms a dimeric structure with an octahedral P4Ba2moiety. Quantum chemical investigations indicate that the structural variety is a consequence of accessibility and spatial extent of the dorbitals of the alkaline earth metal atoms.

The reaction of tBuPh2SiPLi2with (Me3Si)2CHAsCl2in molar ratio 1:1 yields the compound [(SiMe3)2CHAsPSitBuPh2]2(1). The structure of 1reveals the formation of a As2P2ring compound. In contrast, the reactions of tBuPh2SiPLi2with (Me3Si)2CHSbCl2or (Me3Si)2CHBiCl2yield the chloro bridged species [tBuPh2SiP{SbClCH(SiMe3)2}2] (2) and [tBuPh2SiP{BiClCH(SiMe3)2}2] (3). Starting from RMe2SiPLi2(R = Thex, Me) the compounds [P{BiClCH(SiMe3)2}3] (4) and [P2{BiClCH(SiMe3)2}4] (5) were obtained from the reactions with (Me3Si)2CHBiCl2. The compounds 1– 5were characterised by single crystal X‐ray diffraction, elemental analysis as well as IR and NMR techniques.

Getting cagey: Dimerisation and coordination to lithium ions was observed after the reaction of the cage [P2{(SiMe2)2O}3] with Li[Al{OC(CF3)3}4]. The obtained complex ion [Li§P4{(SiMe2)2O}6]+can be decomposed by addition of THF yielding the free dimeric ligand [P4{(SiMe2)2O}6].

The cyclic tetrasilaphosphane iPr2Si4PH 6 can be synthesised in five steps starting from diisopropylchlorsilane and [LiDMEPH2]. Subsequent lithiation and oxidative coupling with dibromethane yields the diphosphane [iPr2Si4P]27. In an analogous manner the bicyclic diphosphane [iPr2Si3P]23 can be obtained from the cyclic trisilaphosphane iPr2Si3PH 1. Moreover, the reaction of 1with [WCO5THF] yields the Lewis acid–base complex [iPr2Si3PHWCO5] 2, and the trimeric lithiumphoshpanide [iPr2Si4PLi]38 occurs from the reaction of 6with nBuLi in heptane. All intermediate and final products are characterised by multinuclear NMR spectroscopy, IR spectroscopy and mass spectrometry. Furthermore, the crystal structures determined by Xray diffraction are described for compounds 2, 3, 6, 7and 8.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Aiming at modulating the packing density within functional self‐assembled monolayers (SAMs), two azo‐biphenyl derivatives AZO1and AZO2comprising a terminal sulfur anchor group have been designed and synthesized. While AZO1allows for a coplanar arrangement of both biphenyl subunits, additional steric repulsion due to two methyl side groups attached to the footing biphenyl of AZO2results in an increased intermolecular distance within the SAM, providing additional free volume. SAMs of both derivatives on gold and platinum substrates have been formed and thoroughly investigated by photoelectron (XPS) and near‐edge absorption fine structure (NEXAFS) spectroscopy as well as cyclic voltammetry and scanning tunneling microscopy. These measurements confirmed the formation of tightly packed SAMs for AZO1, while AZO2formed SAMs consisting of less organized and more loosely packed molecules. Optical investigations of both azo derivatives in solution as well as their SAMs displayed efficient photoisomerization in solution and in SAMs. Comparable maximal cis/transratios of ca. 0.9 have been observed in all cases upon irradiation at λ= 370 and 360 nm for AZO1and AZO2, respectively. The thermally induced cis→ transback reaction on AZO1was found to be slower by a factor of 3 in SAMs as compared to solution, while AZO2displayed comparable rates of the back reaction in both environments. This behavior can be explained by the different nature of molecular isomerization in the two SAM systems: whereas the isomerization in AZO1SAMs takes place in a highly coordinated, collective way and involves many adjacent molecules, AZO2species behave rather individually even packed in SAMs, such that their isomerization process is similar in SAMs and in solutions.

Hauptgruppenelementverbindungen mit Anwendungspotenzial stehen weiter im Fokus – unter anderem stabile niedervalente Verbindungen und Mehrfachbindungssysteme. Bauarbeiten am Fundament und an der Spitze kennzeichnen die Entwicklung der Koordinationschemie im letzten Jahr. Eisenzeit herrscht in der Bioanorganik: Die Zahl der Publikationen zu biologisch relevanten Eisenverbindungen steigt rasant.

The range of molecular silicon phosphorus compounds has been extended by some new species containing oligosilane ((R2Si)n; n ≥ 2) or oligosiloxane ((R2SiO)mSiR2; m ≥ 1) fragments bound to phosphorus atoms. Primary and secondary compounds of these types allow for the synthesis of metal derivatives. Such metalated species usually form oligomers and exhibit a versatile structural chemistry with cyclic, polycyclic, and cage‐like patterns. The main results obtained in the field of oligosilane‐ and oligosiloxane‐bridged phosphines will be presented below and the structures of the metal derivatives will be discussed. Moreover, the synthesis of an inorganic ligand on the basis of siloxane‐bridged phosphines will be presented. This compound opens up a new chapter in host‐guest chemistry.

The synthesis of molecular rod 1comprising a central redoxactive unit and two terminal acetylprotected sulfur groups is reported. Various protecting groups for the catechol moiety were investigated and protected precursors 14–18were synthesized. In particular, ethyl orthoformate 17can be easily and selectively deprotected in mild acidic conditions ruling out the need for a strong Lewis acid like boron tribromide. The redox activity of 1was confirmed by cyclic voltammetric investigations. Gold–molecule–gold junctions were formed with the dimethylprotected rod 18. Singlemolecule transport investigations using this molecular rod revealed a set of three singlejunction conductance values varying over two orders of magnitude.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008

Synthesis and Metalation of the Diphosphanyldisilane iPr4Si2(PH2)2, of the cyclic Silylphosphane (iPr2Si)3PH as well as of the cyclic Siloxylphosphane tBu2Si(OSiiPr2)2PH

The design and synthesis of the molecular cruciforms 1–4 consisting of an oligophenylene-ethynyl backbone with an acetyl-protected sulfur anchor group on one end and a crossing oligophenylene cross-bar with terminal trifluoromethyl and dimethylamino groups as transversal push-pull system are reported. These cruciforms 1–4 are model compounds to investigate electronic potential-dependent switching properties of molecular junctions. While the oligophenylene-ethynyl backbone is responsible for the electronic transport properties, the transversal push-pull system should alter the tilt angle of the rod upon alignment in an electric field. As the tunnel distance at the rods end to the opposite electrode depends on the tilt angle of the rod, a considerable dependence of the transport current on the tilt angle is expected. The investigation of such transport mechanisms with the model compounds 1–4 may unravel the origin of negative differential conductance phenomena in devices consisting of sandwiched self assembled monolayers between two electrodes. The reported cruciform structures display limited stability features in the presence of acids. Their assembly is based on metal catalyzed cross coupling reactions with the chromatographic separation of two, on opposite sides monoprotected regioisomers as key step.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Hauptgruppenelementverbindungen überraschen weiter durch Vielfalt in den Strukturen und Bindungstypen; Moleküle mit Anwendungspotential rücken in den Blickpunkt. Metalle stabilisieren reaktive und aktivieren reaktionsträge Moleküle; Metall‐ komplexe geben Impulse in der Katalyse, der Sensorik und den Materialwissenschaften. Die bioanorganische Chemie nimmt feinste Details biologischer Systeme ins Visier.

The compound [BiP(SiPh2tBu)2]2 (1), featuring a Bi–Bi double bond and two Bi–P single bonds, has been obtained from thereaction of BiCl3 with the lithium phosphanide LiP(SitBuPh2)2.As a byproduct of this transmetallation/redox reaction the diphosphane P2(SitBuPh2)4 (2) has been isolated. This compound shows a remarkably short P–P bond due to π interactions of the phosphorus atoms. The reaction of the dilithium phosphandiide Li2PSitBuPh2 with BiCl3 yielded the bicyclic compound [Bi2(PSiPh2tBu)4] (3), exhibiting a Bi–Bi single bond. NMR studies of 3 show the availability of four different P atoms, as observed in the crystal structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The design and synthesis of the macrocycles 1 and 2 as model compounds for the investigation of negative differential conductance phenomena in molecular junctions are reported. The macrocycles 1 and 2 comprise a molecular rod subunit consisting of three ethynyl-linked phenyl rings. While the rotational freedom along the rod axis of both terminal phenyl rings is limited by the macrocyclic frame, the central phenyl ring is revolving. The rod substructure is terminally functionalized with acetyl-protected thiol groups to enable its immobilization between gold contacts. The central phenyl ring is functionalized with one and two nitro groups for 1 and 2, respectively. The nitro groups are of particular importance as i) both macrocycles are model compounds to investigate a hypothetical intramolecular interaction of the nitro group with the opposite macrocyclic subunits and ii) the nitro group(s) result in limited thermal stability of the compounds due to the intramolecular rearrangement to macrocycles comprising isatogen subunits. These highly functionalized macrocycles have been assembled by acetylene scaffolding strategies in combination with functional group transformation chemistry.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The reaction of [LiAl(PHMe)4] with iPr2SiCl2 yields the dialkyldiphosphanylsilane iPr2Si(PHMe)2 (1). This compound is formed as a diastereomeric mixture and was identified by NMR spectroscopy and mass spectrometry. Silane 1 reacts with [Sn{N(SiMe3)2}2] and [Zn{N(SiMe3)2}2] to form the polycyclic compounds [Sn{SnN(SiMe3)2}2{iPr2Si(PMe)2}2] (2) and [{ZnN(SiMe3)2}3{iPr2Si(PMe)2}2H] (3), respectively. The tricyclic compound 2 possesses one Sn–Sn bond and contains tin atoms in the formal oxidation states +1, +2 and +3. The central structural motif of the zinc–phosphorus cluster 3 is a Zn3P4Si2 cage. The compounds [iPr2Si{P(Me)MEt2}2]2 (4: M = Al; 5: M = Ga), which feature an adamantane-like cage formed by four metal, four phosphorus and two silicon atoms can be obtained by the reaction of 1 with MEt3 (M = Al, Ga). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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The synthesis of biphenyls substituted with nitronyl-nitroxide organic radicals is described. To investigate the Suzuki-type cross-coupling reaction conditions in the presence of the radical, a model compound 1 was prepared. The successful coupling was extended to cyano-functionalized, biphenylic, paramagnetic molecules. Both the ortho- and meta-iodophenyl-nitronyl-nitroxide radicals were used to synthesize radicals 2 and 3. The characterizations of the spin-labelled molecules obtained by this synthetic strategy include two X-ray crystal structures and magnetic measurements. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Synthesis and Characterization of the 1,2‐Diphosphanyldisilanes [Me4Si2(PH2)2] and [Me4Si2(PHMe)2] as well as their Reactions with n‐Butyllithium

The low-temperature reactions of Me2ThexSiPLi2 (Thex = CMe2iPr) and iPr3SiAsLi2 with SbCl3 in a 3:2 molar ratio yields the cage compounds [Sb4(PSiMe2Thex)4] (1) and [Sb4(AsSiiPr3)4] (2), respectively. The metal salt SbBr3 reacts with tBuPh2SiPLi2 at −70 °C to give the bicyclic compound [Sb2(PSiPh2tBu)4] (3). Compounds 1−3 were characterised by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single-crystal X-ray diffraction. The structures of 1 and 2 reveal that the both compounds adopt a structure similar to those of realgar (As4S4). The central structural motif is an Sb4Y4 cage (Y = P, As), consisting of four five-membered rings with common edges. The bicyclic compound 3 is composed of five-membered and three-membered rings sharing a common Sb2 bridgehead. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Natriumaluminiumhydrid reagiert mit H2PSiMe3im molaren Verhältnis 1:4 zu der Verbindung [H2Al{P(SiMe3)2}2Na(dme)2] (1). Zentrales Strukturmotiv dieser Verbindung ist ein viergliedriger AlP2Na‐Ring, dessen Phosphoratome überraschenderweise zwei Silylsubstituenten aufweisen. Wird NaAlH4mit dem primären Silylarsan H2AsSiiPr3in THF umgesetzt, so bildet sich die ionische Verbindung 2, in der cyclische [(H2Al)3(AsSiiPr3)3]3‐‐Anionen sowohl über die freien Elektronenpaare der Arsenatome als auch über Hydridliganden an die Natriumgegenionen koordinieren.

Durch Umsetzung von AlCl3mit Li2AsSiRMe2(R = CMe2iPr) in einem Gemisch aus Ether und Heptan kann die etherstabilisierte polycyclische Verbindung [(AlCl)4(AsSiRMe2)4(Et2O)2] (4) mit leiterartigem Al4As4‐Grundgerüst erhalten werden. Ihr Aufbau gleicht weitgehend dem der Aluminium‐Phosphorverbindung [(AlCl)4(PSiiPr3)4(Et2O)2] (1), über die kürzlich berichtet wurde [1]. Diese Verbindungen können durch Umsetzung mit Pyridin bzw. NEt3zu den cyclischen Spezies [{AlCl(C5H5N)}2(PSiiPr3)2] (3) und [{AlCl(NEt3)}2(AsSiRMe2)2] (5) gespalten werden. Die Verbindungen 3, 4und 5wurden durch Kristallstrukturanalysen charakterisiert.

InEt3reagiert mit H2PSiiPr3zunächst zu der cyclischen Verbindung [Et2InP(H)SiiPr3]2(2). 2liegt als cis/trans‐Iso merengemisch vor und wurde durch 31P‐NMR‐Spektroskopie, IR‐Spektroskopie sowie durch Massenspektrometrie charakterisiert. In Lösung zersetzt sich 2bei Raumtemperatur im Laufe weniger Tage unter weiterer Ethanabspaltung zu der Käfigverbindung [EtInPSiiPr3]4(3). Durch Umsetzung von InEt3mit H2AsSiiPr3erhält man die zu 3analoge Arsenverbindung [EtInAsSiiPr3]4(4); gemeinsames zentrales Strukturmotiv von 3und 4ist ein In4E4‐Heterokubankäfig (E = P, As). Im Gegensatz dazu führt die Reaktion von InEt3mit H2PSiMe2Thex (Thex = CMe2iPr) zu der hexagonal‐prismatisch aufgebauten Verbindung [EtInPSiMe2Thex]6(5).

The reaction of AlCl3with Li2PR (R = SiiPr3, SiMeiPr2) in a mixture of heptane and ether yields in the polycyclic compounds [(AlCl)4(μ3‐PR)2(μ‐PR)2(Et2O)2](1a: R = SiiPr3; 1b: SiMeiPr2) with a ladder‐shaped Al4P4core. The coordination sphere of the outer aluminium atoms in these compounds is completed by ether ligands. In contrast, the reaction of AlCl3with Li2PSiiPr3in pure heptane yields in the formation of the hexagonal prismatic compound [(AlCl)6(μ3‐PSiiPr3)6](2). 1and 2were characterized by single crystal X‐ray diffraction analysis as well as by 31P{1H} and 27Al NMR spectroscopy. The structure determining effect of the solvent can be rationalized by quantumchemical calculations, which also show that the hexagonal prismatic structure is the most stable of the investigated oligomers in absence of ether.

Et3In · PR3(R = Et, iPr) reagiert mit H2ESiMe3unter Abspaltung von C2H6und EH3zu den cyclischen Verbindungen [Et2InE(SiMe3)2]2(1 a: E = P, 1 b: E = As). 1besteht aus einem planaren, viergliedrigen In2E2‐Ring in welchem sowohl die Indium‐ als auch die Phosphor‐ bzw. Arsenatome die Koordinationszahl vier aufweisen. Im Gegensatz dazu haben die Phosphor‐ bzw. Arsenatome in [GaCl(PtBu2Me)E(SiMe3)]2(2 a: E = P, 2 b: E = As) nur die Koordinationszahl drei. 2entsteht bei der Umsetzung von GaCl3· PtBu2Me mit As(SiMe3)3bzw. Li2PSiMe3und hat als zentrales Strukturmotiv einen gewickelten Ga2E2‐Vierring. 1und 2wurden sowohl durch 1H‐ und 31P{1H}‐NMR‐Spektroskopie als auch durch Einkristallstrukturanalyse charakterisiert.

[As7(SiMe3)3] reacts with [(Cp*CoCl)2] to give black crystals of the ionic compound [(Cp*Co)3As6][CoCl4] (1). The cation [(Cp*Co)3As6]2+consists of an As6prism, with squares capped by [Cp*Co] fragments. When [(CptBuCoCl)2] is used instead of [(Cp*CoCl)2] in the reaction, dark red crystals of [(CptBuCo)3As6][CoCl3(thf)]2(2) and green–black crystals of [(CptBuCo)2As4][Co3Cl8(thf)2] (3) can be obtained. The cation in 2shows a structure very similar to that of 1. The [(CptBuCo)2As4]2+cations in 3can be described as a triple‐decker sandwich complex with two [CptBuCo]+fragments bridged by an As4ligand. Density functional calculations reproduce the experimental data of 1and 3and allow an interpretation of molecular electronic structure and bonding in these and related compounds with As replaced by P and Co by Fe.

Synthesis and Metalation of the Diaminosiloxane O(SiiPr2NH2)2

Annähernd C3-symmetrisch ist das 19atomige In-P-Polyedergrundgerüst der bei der Reaktion von InCl3 mit PEt3 und PhP(SiMe3)2 entstandenen Titelverbindung (siehe Struktur), in der neben In-P- auch In-In- und P-P-Bindungen vorliegen. An diesen Clusterkern sind sechs terminale Chlorliganden und drei PEt3-Liganden gebunden, und in der Mitte des Clusters befindet sich ein Chloridion.

The compound [PbAsSiiPr3]6(1) could be obtained by the reaction of PbCl2with iPr3SiAs(SiMe3)2in THF at 0 °C. Central structural motif is a hexagonal prism built by six lead and six arsenic atoms. The average Pb—As bond length is 281 pm. The cluster crystallizes in the monoclinic space group C2/c, the lattice constants are: a= 4460.8(9) b= 2296.6(5), c= 2734.4(6) pm, β= 117.57(3)°. The thermogravimetric analysis in vacuum shows the tendecy of 1to decompose under formation of elementary lead and volatile arsenic compounds.