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Owing to the highly electron-withdrawing C 2 F 5 groups, the tris(pentafluoroethyl)germane (C 2 F 5 ) 3 GeH represents an interesting Brønsted acidic compound. The germane is accessible by the treatment of the corresponding halogenogermanes (C 2 F 5 ) 3 GeX (X=Cl, Br) with Bu 3 SnH. After clarifying its molecular structure in the solid state by X-ray diffraction, the acidity of (C 2 F 5 ) 3 GeH was examined by treatment with different bases, for example, 1,8-bis(dimethylamino)naphthalene. The resulting germanate(II) ion [Ge(C 2 F 5 ) 3 ] - serves as a germyl group transfer reagent. The reaction with main-group and transition-metal complexes or organohalides opens access to a variety of different compounds, the structures of which were mostly determined by X-ray diffraction. The corresponding tricarbonylnickelate(0) complex [(CO) 3 NiGe(C 2 F 5 ) 3 ] - also gives information about the π-acceptor properties of the [Ge(C 2 F 5 ) 3 ] - ligand. Furthermore, hydrogermylation reactions of (C 2 F 5 ) 3 GeH with alkynes afforded different stereoisomers (α,β-cis, β-trans) depending on the respective reaction conditions and substrates., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Gabapentin, an antiepileptic drug, is known to form stable helical structures in short peptides. Distinctly, we report on the newly synthesized γ-analogue of gabapentin, that is, γ-gabapentin (γ-Gpn), which manifests β-sheet character at molecular and nanofibrous hydrogels at the supramolecular level. We investigated the influence of proximally immobilized cationic amino acids (lysine and arginine) on the self-assembly of backbone-expanded tripeptide motif. Interestingly, arginine was found to be superior, both physically and mechanically, over lysine in driving hydrogelation. We have concluded that intrinsic and biochemically distinct properties of the guanidinium ion of arginine (compared to ammonium ion of lysine) have contributed towards this effect. Furthermore, similar to pyroglutamyl (pGlu) modified amyloid β peptides, N-pGlu modification of our self-assembling tripeptide motif exerts a dramatic influence on aggregation and exhibits enhanced β-sheet character, accelerated self-assembly kinetics, improved optical transparency and provides higher mechanical stiffness to the peptide hydrogel., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

After numerous attempts over the last seven decades to obtain a structure for the simple, highly symmetric molecule tetranitromethane (C(NO 2 ) 4 , TNM) that is consistent with results from diffraction experiments and spectroscopic analysis, the structure has now been determined in the gas phase and the solid state. For the gas phase, a new approach based on a four-dimensional dynamic model for describing the correlated torsional dynamics of the four C-NO 2 units was necessary to describe the experimental gas-phase electron diffraction intensities. A model describing a highly disordered high-temperature crystalline phase was also established, and the structure of an ordered low-temperature phase was determined by X-ray diffraction. TNM is a prime example of molecular flexibility, bringing structural methods to the limits of their applicability., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Tris[tetrafluoro-4-(trifluoromethyl)phenyl]borane (BTolF) was prepared by treating boron tribromide with tetrameric F 3 CC 6 F 4 -Cu I . The F 3 CC 6 F 4 -Cu I was generated from F 3 CC 6 F 4 MgBr and copper(I) bromide. Lewis acidities of BTolF evaluated by the Gutmann-Beckett method and calculated fluoride-ion affinities are 9 and 10 %, respectively, higher than that of tris(pentafluorophenyl)borane (BCF) and even higher than that of SbF 5 . The molecular structures of BTolF and BCF were determined by gas-phase electron diffraction, that of BTolF also by single-crystal X-ray diffraction., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Four-membered biradicaloid compounds containing a N 2 E 2 (E=main group element) framework have been thoroughly investigated; however, the synthesis of stable analogues with a C 2 P 2 skeleton remains a challenge. Base-mediated double C-H functionalization of IPr=CH 2 (1) (IPr=C[N(2,6-iPr 2 -C 6 H 3 )CH] 2 ) with PCl 3 affords [{(IPr)CP} 2 Cl]Cl (2) as a royal blue solid. Treatment of 2 with KC 8 yields the stable phosphorus biradicaloid [(IPr)CP] 2 (3) featuring a four-membered C 2 P 2 ring. Compound 3 is diamagnetic and shows sharp and temperature-independent NMR resonances, revealing its singlet biradicaloid nature. The stability of 3 is attributed to the σ- and π-electron-donating property of the N-heterocyclic vinylidene [(IPr)C] group., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This study presents a potential experimental approach to the still elusive topologically nonplanar (K 5 ) parent hydrocarbon, centrohexaquinane (1), by a construction-dismantling (aufbau-abbau) strategy via electron-rich aromatic centropolyindanes. A series of veratrole-based centropolyindanes are synthesized and subjected to ozonolytic degradation. These include the 2,2'-spirobiindanes 30-32, fuso-diindane 33, triptindanes 34-36, tribenzotriquinacene 37, and tetramethoxycentrohexaindane 9. Spirane 30 and propellane 36 are characterized by X-ray structure analysis. Ozonolysis of 32 and 33 gives a keto ester (59) and a dimethyl muconate (60), respectively. Dimethoxytriptindane 34 gives a [3.3.3]propellane-cis,cis-muconate (61) in good yield, the stereochemistry of which is determined by X-ray structure analysis. Tetramethoxytriptindane 35 gives the [3.3.3]propellane-bis-muconate 62 along with a [3.3.3]propellane-dialdehyde-muconate (63). Hexamethoxytriptindane 36 furnishes three products of mainly intra-dimethoxy cleavage, with the [3.3.3]propellane-tris-muconate 64 as the major component. X-ray structure analysis of 64 reveals molecular C 3 symmetry and all-cis,cis stereochemistry of the three muconate groups. Hexamethoxytribenzotriquinacene 37 gives the triquinacene-tris-muconate 68, albeit in very low yield. Ozonolysis of tetramethoxycentrohexaindane 9 affords the bis-muconate 10 in moderate yield, along with two further centrohexacyclic products of single-wing degradation., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis and characterization of the N-heterocyclic carbene (NHC) stabilized dichlorosilylene Group 6 metal complexes {(IPr)SiCl 2 }W(CO) 5 (3-W), {(IPr)SiCl 2 } 2 Cr(CO) 4 (4-Cr), and {(IPr)SiCl 2 } 2 W(CO) 4 (4-W) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) are reported. Treatment of 3-W with CsOH in the presence of IPr leads to the formation of an abnormal-NHC (aNHC) metal complex (aIPr H )W(CO) 5 (6-W) (aIPr H = 1,3-bis(2,6-diisopropylphenyl)imidazol-4-ylidene), unveiling an unprecedented normal-to-abnormal transformation route of an NHC. DFT calculations support the proposed mechanism that involves CsOH mediated deprotonation of the IPr-backbone of 3-W to yield a ditopic carbanionic-NHC (dcNHC) complex 5a-W. Subsequent 1,4-migration of the W(CO) 5 moiety and hydrolysis of the unmasked SiCl 2 rationalize the formation of 6-W. The desired H 2 O molecule is generated in the initial step on deprotonation of IPr with CsOH. In contrast to the literature precedents, the calculations indicate that the abnormal complex 6-W is 13.5 kcal mol -1 thermodynamically higher in energy than the normal counterpart (IPr)W(CO) 5 (8-W). Interestingly, as the aNHC-compounds reported so far are more stable than their normal counterparts, this finding showcases an opposite trend. Moreover, reaction pathways to the synthesized and related complexes have been investigated by DFT calculations.

For (pentafluoroethyl)phenylstannanes, (C 2 F 5 ) 4-n  SnPh n (n=1-3), and dimethylbis(pentafluoroethyl)stannane, (C 2 F 5 ) 2 SnMe 2 , a high yield synthesis was developed by the use of LiC 2 F 5 as a C 2 F 5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C 2 F 5 ) 4-n SnX n (X=Cl, Br; n=1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1 H, 13 C, 19 F and 119 Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C 2 F 5 ) 4-n SnX n with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C 2 F 5 ) 4-n SnX n (phen)], the structures of which were elucidated by X-ray diffraction analyses. The bromostannane (C 2 F 5 ) 3 SnBr reacted with sodium cyclopentadienide to give the (η 1 -cyclopentadienyl)tris(pentafluoroethyl)stannane, (C 2 F 5 ) 3 SnCp, for which single-crystal X-ray diffraction analysis could be performed. The coupling constants 1 J( 119 Sn, 13 C) and 2 J( 119 Sn, 19 F) of all new stannanes are strongly correlated and sensitive to the substitution pattern at the tin atom. For both coupling constants a negative sign could be assigned., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Bidentate gallium Lewis acids were prepared by the reaction of diethynyldiphenylsilane with neat trimethyl- or triethylgallium. Bis[(dimethylgallyl)ethynyl]diphenylsilane (1) and diethylgallyl derivative 2 were characterized as Et 2 O or pyridine adducts by NMR spectroscopy; 2⋅2Py was isolated. Lewis acids 1 and 2 form host-guest adducts with bidentate nitrogen bases, but defined cyclic 1:1 adducts are only formed between 1 and bases with matching N⋅⋅⋅N distances: 4,4'-dimethyl-3,3'-bipyridinylacetylene (3), bis[(pyridin-3-yl)ethynyl]diphenylsilane (4), and bis[(2-methylpyridin-5-yl)ethynyl]diphenylsilane (5). The structures of adducts 1⋅3, 1⋅4, and 1⋅5 were established by X-ray diffraction experiments. 2⋅2Py reacts with DABCO to afford polymeric (DABCO-2-) n ., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

New geminally bonded intramolecular donor-acceptor systems, Cp 2 LnCH 2 PR 2 (Ln = Y, Ho, Er, R = CHMe 2 , CMe 3 ), were prepared by salt elimination reactions between the dicyclopentadienyl-element chlorides (Cp 2 LnCl, Ln = Y, Ho, Er) and diorganylphosphinomethanides (R 2 PCH 2 Li; R = CHMe 2 , CMe 3 ). These compounds, 1-6, were characterized by elemental analyses, mass spectrometry and X-ray diffraction experiments and the yttrium species additionally by NMR spectroscopy. In the solid state the molecular structures differ from each other, depending on the steric demand of the phosphorus substituents. For all iso-Pr-substituted compounds, dimers [Cp 2 LnCH 2 P(CHMe 2 ) 2 ] 2 with six-membered Ln-C-P-Ln-C-P rings in a chair-like conformation were observed. The sterically more demanding tert-butyl groups prevent dimerization but instead lead to species that undergo complexation of LiCl units by two monomers: [Cp 2 LnCH 2 P(CMe 3 ) 2 ·LiCl]. The solution NMR data for the yttrium compounds are consistent with the solid-state structures. Conversion with phenylacetylene afforded heteroleptic cyclobutane-like alkynyl-rare-earth metal complexes [Cp 2 Ln(μ-C[triple bond, length as m-dash]CPh)] 2 [Ln = Y (7), Ho (8), Er (9)]. Treatment of compounds 1-6 with 1,8-diethynylanthracene led to single metalation and dimerization and products with similar structural motifs as observed for complexes 7-9. Reactions with dihydrogen and carbon dioxide resulted in Y-C bond breaking, yielding Cp 2 YH/R 2 PCH 3 and CO 2 insertion products, respectively.

The pharmacological and physicochemical analysis of structurally optimized N-alkyl-substituted indazole-5-carboxamides, developed as potential drug and radioligand candidates for the treatment and diagnosis of Parkinson's disease (PD) and other neurological disorders, is reported. Recent efforts have been focused on the development of subnanomolar potent, selective MAO-B (N1-alkyl-substituted compounds 12a-14a and 15) and dual active MAO-A/B (N2-methylated compounds 12b-14b) inhibitors with nanomolar potency towards MAO-B and moderately active against MAO-A enzyme, respectively. The most promising drug-like derivatives in both series were N-(3-chloro-4-fluorophenyl)-1-methyl-1H-indazole-5-carboxamide (13a, NTZ-1441, IC 50 hMAO-B 0.662 nM, >15000-fold selective versus MAO-A) and N-(3-chloro-4-fluorophenyl)-2-methyl-2H-indazole-5-carboxamide (13b, NTZ-1442, IC 50 hMAO-B 8.08 nM, IC 50 hMAO-A 0.56 μM, SI = 70). Moreover, compounds 13a and 13b were predicted to cross both the gastrointestinal tract (at pH 2.0, 5.5, and 7,4) and the blood-brain barrier (BBB) in vitro with appropriate drug-like properties required for CNS active drugs. Combined single X-ray/molecular modeling studies provided insights into the enzyme-inhibitor interactions within both MAO isoforms and the rationale for their inhibitory activity with controlled MAO-A/B selectivity - despite their small structural differences. The binding modes of 12a,b and 13a,b confirmed that the major interactions with hMAO-B were established via the flexible carbonyl group of the carboxamide linkage and the electron-donating nitrogens N1 or N2 of the indazole moiety, allowing further exploration of the alkyl side chain for next step lead optimization efforts., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Diethynyldiphenylsilane (1) and divinyldiphenylsilane (2) were functionalized by hydrosilylation reactions with HSiMe 2 Cl, HSiMeCl 2 and HSiCl 3 . Fluorination of the resulting compounds generates bidentate open-chain Lewis acids of increasing acidity. All semi-flexible [Ph 2 Si(CH[double bond, length as m-dash]CHSiF n Me 3-n ) 2 (n = 1, 2, 3)] and flexible [Ph 2 Si(CH 2 -CH 2 SiF n Me 3-n ) 2 (n = 1, 2, 3)] bidentate Lewis acids were obtained in good to excellent yields. The different fluoride ion complexation behavior was explored in detail by multinuclear (low temperature) NMR spectroscopy. The Lewis acidic bidentate molecules as well as the resulting mono- and bissilicates were completely characterized by NMR spectroscopy, mass spectrometry and in part by elemental analysis and X-ray diffraction experiments.

Commercially available BiPh 3 was treated with perfluoroalkylphosphinic acids [for example, (C 2 F 5 ) 2 P(O)OH] to generate novel, highly Lewis acidic bismuth(III) perfluoroalkylphosphinates of the type Ph x Bi[R F 2 PO 2 ] 3-x (x=0, 1, 2) (R F =-C 2 F 5 , -C 4 F 9 ). The first bismuth(V) perfluoroalkylphosphinate, Ph 3 Bi[(C 2 F 5 ) 2 PO 2 ] 2 , was synthesized from Ph 3 BiCl 2 and Ag[(C 2 F 5 ) 2 PO 2 ]. Examples for the successful application of the catalytically active bismuth(III) and bismuth(V) phosphinates in carbon-carbon bond forming reactions, such as Friedel-Crafts acylation and alkylation, Diels-Alder, Strecker and Mannich reaction, are presented., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of tris-, bis-, and mono(pentafluoroethyl)bismuthanes of the type (C 2 F 5 ) n BiX 3-n (X=F, Cl, Br, I) and transition metal complexes are accessible by a sophisticated pentafluoroethylation protocol. Chemical properties, induced by the strongly electron-withdrawing character of C 2 F 5 groups, are described for representative examples. Moreover, the first molecular structures of perfluoroalkyl bismuthanes and bismuthates obtained by X-ray diffraction are presented., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Several derivatives of the propeller-shaped ortho-substituted triphenylsilanes, carrying metal- or silicon-based acceptor groups, are reported. They were synthesized starting from tris(2-bromophenyl)fluorosilane, tris(2-vinylphenyl)fluorosilane and tris(2-ethynylphenyl)fluorosilane to generate a scope of Lewis-acidic molecules with different cavities. An improved synthetic protocol for donor-free tris(2-lithiophenyl)silanes is described. First attempts in host-guest chemistry to probe the binding between a threefold alane-functionalised ortho-substituted triphenylsilane and a tridentate Lewis-basic guest molecule are presented. The synthesis and a first molecular structure determination in the crystalline state of a bismasilatriptycene is reported.

Several derivatives of bowl-shaped tribenzotriquinacenes with Lewis-acidic atoms are reported. Six acetylene functions were attached to the benzene rings and these can carry six SnMe 3 or SiMe 3 groups. Direct functionalization of the benzhydrylic positions with the silyl groups of tribenzotriquinacene in in situ Grignard reactions is reported. Such silyl groups carry various substituents; the Si-H functional species were shown to be convertible into Si-F, Si-Cl and Si-Br functional compounds. The benzhydrylic positions were also substituted by allyl and p-iodo-phenyl functions; the first were further functionalized with a variety of silyl groups (SiCl 3 , SiMeCl 2 , SiF 3 , SiMeF 2 ), the latter with trimethylsilylethynyl substituents and this product desilylated to a tris-(p-ethynyl-phenyl) tribenzotriquinacene. The complexation of a SbCl 3 unit by a tribenzotriquinacene derivative with a new chelating tris-arene binding motif of the antimony atom is also reported.

The tris(pentafluoroethyl)silanide anion is accessible by the deprotonation of Si(C 2 F 5 ) 3 H at low temperatures. Subsequent quenching of the resulting salt-like compounds with suitable electrophiles, such as transition-metal complexes or Group 14 element halides, leads to a plethora of novel tris(pentafluoroethyl)silane derivatives. This underlines the versatility of Li[Si(C 2 F 5 ) 3 ] as a powerful nucleophilic transfer reagent., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Tris(pentafluoroethyl)silane, which is conveniently accessible by the treatment of Si(C 2 F 5 ) 3 X (X=Cl, Br) with Bu 3 SnH, was successfully employed for hydrosilylation reactions. In the presence of a palladium catalyst, hydrosilylation of phenylacetylene with Si(C 2 F 5 ) 3 H affords the product of an α-addition whereas the reaction of trimethylsilylacetylene with the silane leads to the β-trans product. Tris(pentafluoroethyl)silane can be deprotonated by sterically demanding bases such as lithium diisopropylamide at low temperatures to give the corresponding silanide ion. The addition of crown ethers or cryptands to this highly reactive species enabled the isolation and characterization of salt-like tris(pentafluoroethyl)silanide at room temperature., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pure anhydrous hexafluorosilicic acid (H 2 [SiF 6 ]) is a still elusive species, although its existence in aqueous solutions is well documented. Desiccation inevitably leads to decomposition to form tetrafluorosilane and hydrogen fluoride. An oxonium hexafluorosilicate turned out to not be stable at room temperature. Partial substitution of the fluorine atoms with strong electron-withdrawing perfluoroalkyl groups results in substantial stabilization of the corresponding fluorosilicic acids. Mono- and bis(pentafluoroethyl)-substituted fluorosilicic acids were prepared through conversion of the respective halosilanes (Si(C 2 F 5 ) n X 4-n , with X=Cl, Br) with aqueous HF, and were obtained as colorless solids. They can be stored at room temperature for several months without decomposition, and thus are the first examples of stable fluorosilicic acids., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

As recently shown, the introduction of pentafluoroethyl functionalities into silicon compounds is of general interest due to an enhanced Lewis acidity of the resulting species. By this means, the synthesis of previously inaccessible hypervalent silicon derivatives is enabled. While an easy access to tris(pentafluoroethyl)silanes has already been published, synthetic strategies for the selective preparation of bis derivatives are yet unknown. In this contribution, a convenient protocol for the synthesis of functional bis(pentafluoroethyl)silicon compounds is presented. These compounds represent precursors for the synthesis of pentafluoroethylated polysiloxanes. Furthermore, they prove to be resistant to oxonium cations, which is a key feature for the preparation of stable pentafluoroethylsilic acids. Treatment of dichlorodiphenoxysilane with in situ generated pentafluoroethyl lithium leads to the corresponding bis(pentafluoroethyl)silane in high yields. (C 2 F 5 ) 2 Si(OPh) 2 serves as a starting material for further functionalized bis(pentafluoroethyl)silanes. These silanes have been isolated and their reactivity towards N bases studied. The pronounced Lewis acidity of the obtained compounds has been documented by the formation of octahedral adducts with nitrogen donors such as 1,10-phenanthroline and acetonitrile., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This paper gives an account on hypervalent fluoro- and chloro(pentafluoroethyl)germanium compounds. The selective synthesis of the tris(pentafluoroethyl)dichlorogermanate salt [PNP][(C 2 F 5 ) 3 GeCl 2 ] as well as its X-ray structural analysis is described. As a representative example for pentafluoroethylfluorogermanates, the synthesis and structure of 2,4,6-triphenylpyryliumtris(pentafluoroethyl)difluorogermanate [C 23 H 17 O][(C 2 F 5 ) 3 GeF 2 ] is reported. Fluoride-ion affinities for pentafluoroethylgermanes were calculated using quantum chemical methods, disclosing (C 2 F 5 ) 3 GeF as a weaker Lewis acid than (C 2 F 5 ) 3 SiF or (C 2 F 5 ) 3 PF 2 . The theoretical results were confirmed by experiments and give the basis of a synthetic protocol for (C 2 F 5 ) 3 GeF. Pentakis(pentafluoroethyl)germanate [PPh 4 ][Ge(C 2 F 5 ) 5 ] was detected as an intermediate during the synthesis of [PPh 4 ][(C 2 F 5 ) 4 GeF] starting from tris(pentafluoroethyl)difluorogermanate and LiC 2 F 5 ., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The doubly acid-functionalised aniline PhN[(CH 2 ) 3 B(C 6 F 5 ) 2 ] 2 shows rapidly exchanging boron acid groups at the central base function and is an active frustrated Lewis pair due to cooperative hydride binding by both Lewis acids. Here we report investigations on the effect of different substituents at the central nitrogen atom and on the effect of exchanging nitrogen by phosphorus. Treatment of diallyl-tert-butylaniline with one equivalent of HB(C 6 F 5 ) 2 led to formation of a seven-membered iminium hydridoborate ring; after mono-hydroboration the intermediately formed frustrated Lewis pair reacts with the second allylamine function under ring closure. Phosphorus based Lewis pairs with two acid sites were prepared by hydroboration of diallylphenylphosphane and diallyl-tert-butylphosphane. Unlike the aniline PhN[(CH 2 ) 3 B(C 6 F 5 ) 2 ] 2 the doubly hydroborated species ( t Bu/Ph)P[(CH 2 ) 3 B(C 6 F 5 ) 2 ] 2 show no dynamic exchange of the boron Lewis acid functions in solution and are not catalytically active in terms of H/D-scrambling as well as hydrogenation reactions. Quantum-chemical investigations revealed the B-P bond dissociation Gibbs free energy to be much larger than those of the nitrogen analogue. The absence of an active open form in solution prevents an activity in heterolytic hydrogen splitting.

Dichlorophosphanyl isocyanate, Cl 2 PNCO, was synthesized and characterized by IR, Raman and 31 P NMR spectroscopy. The conformational properties and molecular structures were studied by using gas electron diffraction (GED), X-ray crystallography and quantum-chemical calculations. Extensive DFT and ab initio calculations show that the potential energy surface of Cl 2 PNCO upon rotating the P-N bond is rather flat; three conformers, namely syn, anti and gauche between the NCO group and the bisector of the ClPCl angle, were theoretically predicted. Experimentally, only one conformer was indicated by gas-phase IR spectroscopy and the preference for a gauche conformation in both gas phase and solid state was unambiguously ascertained by gas electron diffraction and X-ray crystallographic data. In the solid state, the Cl 2 PNCO molecules adopt a gauche conformation with two distinct dihedral angles Cl-P-N-C of -121.3(2) and 137.4(2)° and form polymeric chains through weak intermolecular CO contacts. Additionally, the dynamic character of the position of the isocyanate group of Cl 2 PNCO was examined in the gas phase.

A modified synthesis for carbonyl diisocyanate, CO(NCO)2, starting from trichloroisocyanuric acid and diphosgene is described. In addition to the previously reported (13)C NMR resonances, the (15)N NMR shift is determined for the first time. The structure in the solid state was determined by X-ray diffraction (XRD) on in situ grown crystals, that in the gas phase was experimentally determined by electron diffraction (GED) and for single molecules theoretically by quantum-chemical calculations. The structures are compared and discussed with related systems. Quantum-chemical calculations as well as GED and XRD prove syn-syn to be the conformation of lowest energy. In quantum-chemical calculations and GED the presence of a syn-anti conformer was confirmed and the structure of this conformer was determined.

The synthesis of the germylene phosphane adduct (C2 F5 )2 Ge⋅PMe3 is described. Starting from (C2 F5 )3 GeH in an excess of PMe3 , heating was applied, whereupon reductive elimination of C2 F5 H occurred. The molecular structure was ascertained by X-ray diffraction and compared with information obtained by quantum chemical methods. The ligand properties were derived by studying the IR spectrum of the nickel(0) complex [Ni(CO)3 {Ge(C2 F5 )2 (PMe3 )}] in the CO region. (C2 F5 )2 Ge⋅PMe3 turned out to be a π-accepting ligand comparable to PMe3 , in terms of Tolman's electronic parameter. Furthermore a [2+4] cycloaddition reaction with 2,3-dimethyl-1,3-butadiene, and σ-bond insertion reactions were recorded. Activation of the C-Cl bond in dichloromethane gives rise to the formation of the phosphonium ylide complex [(C2 F5 )2 Cl2 Ge-CH2 PMe3 ], which was fully characterized by X-ray diffraction., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The solid-state molecular structure of centrohexaindane (), a unique hydrocarbon comprising six benzene rings clamped to each other in three dimensions around a neopentane core, and the molecular packing in crystals of ·CHCl3 are reported. The molecular Td-symmetry and the Cartesian orientation of the six indane wings of in the solid state have been confirmed. The course and limitation of electrophilic aromatic substitution of are demonstrated for the case of nitration. Based on nitration experiments of a lower congener of , tribenzotriquinacene , the six-fold nitrofunctionalisation of has been achieved in excellent yield, giving four constitutional isomers, two nonsymmetrical ( and ) and two C3-symmetrical ones ( and ), all of which contain one single nitro group in each of the six benzene rings. The relative yields of the four isomers (∼3 : 1 : 1 : 3) point to a random electrophilic attack of the electrophiles at the twelve formally equivalent outer positions of the aromatic periphery of , suggesting electronic independence of its six aromatic π-electron systems. In turn, the pronounced conformational rigidity of the centrohexacyclic framework of enables the unequivocal structural identification of the isomeric hexanitrocentrohexaindanes by (1)H NMR spectroscopy.

The coexistence of two conformers in perfluoropropanoyl fluoride, CF3CF2C(O)F, differing in the CC-CF dihedral angle (gauche 85(10)% and anti 15(10)%), has been determined by means of gas-phase electron diffraction (GED). Quantum-chemical calculations performed at the MP2 and B3LYP approximations and cc-pVTZ basis sets reproduce the experimental values with confidence. By contrast, FTIR spectra give no clear evidence for the anti-conformer in the gas phase. Information on this less abundant but stable rotamer is obtained from matrix-isolation/FTIR spectroscopy and liquid Raman spectroscopy. In situ crystallization and single-crystal X-ray diffraction (XRD) data reveal the presence of solely the gauche-conformation in the solid state. A set of intermolecular interactions including C═O···C═O, C-F···F-C, and F···C═O is detected. The nature of bonding and the relative stabilities of gauche- and anti-conformers are explored using natural bond orbitals.

The chemistry of bis(pentafluoroethyl)germanes (C2F5)2 GeX2 is presented. The synthesis of such species requires Br2 GePh2 , wherein the phenyl substituents function as suitable protecting groups. After treatment with two equivalents of LiC2 F5, (C2F5)2 GePh2 is produced. The replacement of the phenyl rings is smoothly effected by gaseous HBr or HCl in the presence of a Lewis acidic catalyst. The trigermoxane [(C2F5)2 GeO]3 results from the reaction of (C2F5)2 GeBr2 with Ag2 CO3. Its crystalline 1,10-phenanthroline adduct was fully characterised by X-ray diffraction. The combination of (C2F5)2 GeBr2 with Bu3 SnH gave rise to the formation of (C2F5)2 GeH2 ., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of tris(pentafluoroethyl)germanium derivatives is described. The reaction of germanium tetrachloride with three equivalents of the pentafluoroethylation reagent LiC 2 F 5 does not lead selectively to the formation of tris(pentafluoroethyl)chlorogermane, (C 2 F 5 ) 3 GeCl. Here the introduction of a diethylamino function as a protecting group was beneficial. Thus, treatment of Cl 3 GeNEt 2 with LiC 2 F 5 smoothly afforded (C 2 F 5 ) 3 GeNEt 2 . The replacement of the amino substituent by halides was accomplished by reaction with HBr or HCl on a multigram scale. The combination of (C 2 F 5 ) 3 GeCl with Ag 2 CO 3 gave rise to the formation of the digermoxane [(C 2 F 5 ) 3 Ge] 2 O. An obtuse Ge-O-Ge angle of 150.2(1)° was determined by X-ray diffraction. Attempted hydrolysis of the digermoxane leads to an equilibrium mixture of the precursor, (C 2 F 5 ) 3 GeOH, and water., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The 1,3,5-trisilacyclohexane skeleton [CH2Si(Ph)(C2H)]3 equipped with three ethynyl groups was synthesised and functionalised to afford tridentate Lewis acids with directed functions. Hydroboration with HB(C6F5)2 yielded the ethenylborane {CH2Si(Ph)[C2H2B(C6F5)2]}3, while metalation with gallium organyls afforded {CH2Si(Ph)[C2Ga(R)2]}3 (R = Me, Et). The new compounds were identified by elemental analyses, multi-nuclear NMR spectroscopy and IR spectroscopy. Crystal structures were obtained for all-cis-[CH2Si(Ph)(OMe)]3, cis-trans-[CH2Si(Ph)(Cl)]3, all-cis-[CH2Si(Ph)(H)]3 and all-cis-[CH2Si(Ph)(C2H)]3.

The charge density distribution of the trimethylaluminum dimer was determined by high-angle X-ray diffraction of a single crystal and quantum-chemical methods and analyzed using the quantum theory of atoms in molecules. The data can be interpreted as Al2Me6 being predominantly ionically bonded, with clear indications of topological asymmetry for the bridging Al-C bonds owing to delocalized multicenter bonding. This interpretation is supported by the calculated magnetic response currents. The data shed new light on the bonding situation in this basic organometallic molecule, which was previously described by contradicting interpretations of bonding., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Inherently chiral acetophenones and benzaldehydes bearing the large, bowl-shaped framework of tribenzotriquinacene (TBTQ) were synthesized in enantiomerically pure form employing enzyme catalysis. Five-step sequences involving lipase CAL-B lead to the (M)-enantiomers, (+)-2-acetyl-TBTQ (M)-5 and (+)-2-formyl-TBTQ (M)-6, whereas use of lipase PS leads to the (P)-enantiomers, (-)-2-acetyl-TBTQ (P)-5 and (-)-2-formyl-TBTQ (P)-6, with at least 99% ee in each case. The absolute configuration of these rigid 3D building blocks was determined by X-ray diffraction analysis of the ketones 5 and by comparison of their chiroptical properties with those of the aldehydes 6., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Frustrated Lewis pairs (FLPs) have a great potential for activation of small molecules. Most known FLP systems are based on boron or aluminum atoms as acid functions, few on zinc, and only two on boron-isoelectronic silicenium cation systems. The first FLP system based on a neutral silane, (C2F5)3SiCH2P(tBu)2 (1), was prepared from (C2F5)3SiCl with C2F5 groups of very high electronegativity and LiCH2P(tBu)2. 1 is capable of cleaving hydrogen, and adds CO2 and SO2. Hydrogen splitting was confirmed by H/D scrambling reactions. The structures of 1, its CO2 and SO2 adducts, and a decomposition product with CO2 were elucidated by X-ray diffraction., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The crystal structure of the title compound, C32H39NO4, confirms the absolute configuration of the seven chiral centres in the mol-ecule. The molecule has a 1,1-dimethylprop-2-enyl substituent on the indole nucleus and this nucleus shares one edge with the five-membered ring which is, in turn, connected to a sequence of three edge-shared fused rings. The skeleton is completed by the 7,7-trimethyl-6,8-dioxabi-cyclo-[3.2.1]oct-3-en-2-one group connected to the terminal cyclohexene ring. The two cyclohexane rings adopt chair and half-chair conformations, while in the dioxabi-cyclo-[3.2.1]oct-3-en-2-one unit, the six-membered ring has a half-chair conformation. The indole system of the mol-ecule exhibits a tilt of 2.02 (1)° between its two rings. In the crystal, O-H⋯O hydrogen bonds connect mol-ecules into chains along [010]. Weak N-H⋯π inter-actions connect these chains, forming sheets parallel to (10-1).

Phosphinic acids, R(f)P(O)(OH)H (R(f)=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of phosphonous acids, R(f)P(OH)2. Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)2}2] and [Pt{P(C2F5)(OH)O}2{P(C2F5)(OH)2}] containing hydrogen-bridged [R(f)P(OH)O](-) and R(f)P(OH)2 units. Further deprotonation of [Pt{P(C2F5)(OH)O}2{P(C2F5)(OH)2}2] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}4](2-), revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd2(μ-Cl)2{[P(C2F5)(OH)O]2H}2] was isolated and characterized. The Cl(-) free complex [Pd{P(C2F5)(OH)O}2{P(C2F5)(OH)2}2] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}4](2-). Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)2}2] and [Pd2(μ-Cl)2{[P(C6F5)(OH)O]2H}2] as well as the CF3 derivative [Pd2(μ-Cl)2 {[P(CF3)(OH)O]2H}2] were synthesized and fully characterized. Phosphonous acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic acid was demonstrated., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

1,8-Bis(phenylethynyl)anthracene (1,8-BPEA) was synthesized by a twofold Kumada cross-coupling reaction. The molecular structure of 1,8-BPEA was determined using a combination of gas-phase electron diffraction (GED), mass spectrometry (MS), quantum chemical calculations (QC) and single-crystal X-ray diffraction (XRD). Five rotamers of the molecule with different orientations of phenylethynyl groups were investigated by DFT calculations. According to these, molecules of C2 symmetry with co-directional rotation of the phenylethynyl groups are predicted to exist in the gas phase at 498 K. This was confirmed by a GED/MS experiment at this temperature. The bonding of this conformer was studied and described in terms of an NBO-analysis. Dispersion interactions in the solid state structure and in the free molecule are discussed. In the solid this symmetry is broken; the asymmetric unit of the single crystal contains 3.5 molecules and a herringbone packing motif of π-stacked dimers and trimers. The π-stacking in the dimers is between the anthracene units, and the trimers are linked by π-stacking between phenyl and anthracene units. The interaction between these stacks can be described in terms of σ(C-H)π interactions.

Directed tridentate Lewis acids based on the 1,3,5-trisilacyclohexane skeleton with three ethynyl groups [CH2Si(Me)(C2H)]3 were synthesised and functionalised by hydroboration with HB(C6F5)2, yielding the ethenylborane {CH2Si(Me)[C2H2B(C6F5)2]}3, and by metalation with gallium and indium organyls affording {CH2Si(Me)[C2M(R)2]}3 (M = Ga, In, R = Me, Et). In the synthesis of the backbone the influence of substituents (MeO, EtO and iPrO groups at Si) on the orientation of the methyl group was studied with the aim to increase the abundance of the all-cis isomer. New compounds were identified by elemental analyses, multi-nuclear NMR spectroscopy and in some cases by IR spectroscopy. Crystal structures were obtained for cis-trans-[CH2Si(Me)(Cl)]3, all-cis-[CH2Si(Me)(H)]3, all-cis-[CH2Si(Me)(C2H)]3, cis-trans-[CH2Si(Me)(C2H)]3 and all-cis-[CH2Si(Me)(C2SiMe3)]3. A gas-phase electron diffraction experiment for all-cis-[CH2Si(Me)(C2H)]3 provides information on the relative stabilities of the all-equatorial and all-axial form; the first is preferred in both solid and gas phase. The gallium-based Lewis acid {CH2Si(Me)[C2Ga(Et)2]}3 was reacted with a tridentate Lewis base (1,3,5-trimethyl-1,3,5-triazacyclohexane) in an NMR titration experiment. The generated host-guest complexes involved in the equilibria during this reaction were identified by DOSY NMR spectroscopy by comparing measured diffusion coefficients with those of the suitable reference compounds of same size and shape., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Bis(diethylamino)pentafluoroethylphosphane represents a versatile starting material for the synthesis of functionalized pentafluoroethylphosphanes. Perfluoroalkyl substituted aminophosphanes themselves already exhibit interesting coordination properties and were treated with the catalytically relevant salts PtCl2 and PdCl2 affording trans-[Cl2M{P(C2F5)(NEt2)2}2]. The hitherto unknown (C2F5)PBr2, accessible in good yields by treatment of C2F5P(NEt2)2 with HBr, was smoothly transformed into the corresponding phosphane, C2F5PH2, or fluoro derivative, C2F5PF2. Acidic hydrolysis of C2F5 P(NEt2)2 yielded the phosphinic acid C2F5P(O)(OH)H, the anion of which was structurally characterized. The phosphinic acid smoothly adds to the carbonyl group of acetone under P-C bond formation. An analogous reaction with aldehydes, for example, salicyl aldehyde, offers the possibility to generate stereocenters., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Diorganophosphane oxides were employed as preligands for the synthesis of catalytically active transition metal complexes of the phosphinous acids (CF3)2POH and (C2F5)2POH. Their reactions with solid PtCl2 and PdCl2 led to the formation of mononuclear phosphinous acid complexes [Cl2M{P(R(f))2OH}2] (M = Pd, Pt; R(f) = C2F5, CF3), which can be crystallized, for example, as its pyridinium salts, 2[HPy](+)[Cl2Pd{P(CF3)2O}2](2-). In vacuo HCl is liberated from the neutral palladium complexes affording mixtures of di- and polynuclear complexes. Moreover, (C2F5)2POH was reacted with several β-diketonato complexes of palladium, platinum, and nickel yielding air- and moisture-stable complexes [(acac)M{[P(R(f))2O]2H}], featuring a quasichelating phosphinous acid phosphinito unit {P(R(f))2O···H···O(R(f))2P}(-). Treatment of [Ni(Cp)2] (Cp = cyclopentadienyl) and [(cod)RhCl]2 (cod = 1,5-cyclooctadiene) with (C2F5)2POH leads to the substitution of one Cp or chloro ligand by a quasichelating unit. The novel coordination compounds were characterized by NMR and IR spectroscopies, mass spectrometry, and X-ray diffraction analysis. The platinum complex [(acac)Pt{[P(C2F5)2O]2H}] (acac = acetylacetonato) was used for the construction of hetero-bimetallic complexes by the treatment with [(cod)RhCl]2 and [Ni(Cp)2]. The trinuclear bimetallic complex [{(acac)Pt[P(C2F5)2O]2}2Ni] is the first structurally characterized hetero-bimetallic species containing a bis(perfluoroalkyl)phosphinito bridge.

To further investigate the α-effect in silanes bearing a geminal donor atom, the model compounds (C2F5)3SiCH2NMe2, (C2F5)3SiCH2OMe and (C2F5)3SiONMe2 were prepared by introduction of pentafluoroethyl groups via nucleophilic substitution of the corresponding chloro-derivatives with pentafluoroethyl lithium. The substances were characterised by NMR spectroscopy and X-ray diffraction via in situ crystallization techniques. The solid state structures of these highly electronegatively substituted α-silanes contain monomeric molecules. The Si-C-N angle in (C2F5)3SiCH2NMe2 shows a value of 115.3(2)° and the Si-C-O angle in (C2F5)3SiCH2OMe a value of 105.4(1)°. Both values are smaller than the Si-C-C angle of the reference compound (C2F5)3SiCH2CH3 with a value of 118.6(2)° indicating attractive interaction between the silicon atom and the respective donor atoms. The Si-O-N angle in (C2F5)3SiONMe2 is extremely narrow at 82.0(1)°. This behaviour was further investigated by gas electron diffraction and by quantum-chemical calculations. The NBO method finds no significant orbital interactions between Si and N/O atoms in the Si-C-N, Si-C-O and Si-O-N units. The IQA model describes the compounds as strongly stabilised by electrostatic interactions between formally non-bonded silicon and donor atoms.

The structural and conformational properties of chloromethyl thiocyanate, CH2ClSCN, were studied in the solid phase and in the gas phase using in situ low-temperature single-crystal X-ray diffraction experiments (XRD) and gas electron diffraction (GED), respectively. Depending on the mutual orientation of the Cl-C bond and the -SCN group, two conformations, gauche and anti, were found to coexist in the gas phase. The gauche conformer, with a dihedral angle φ(ClC-SC) = 71.8(4)°, is the most stable form, with an abundance of 89(3)% at ambient temperature. High level quantum-chemical calculations at the CCSD(T)/cc-pVTZ level of approximation reproduce these experimental results. In the solid state only gauche conformers were found to be present. The crystal structure shows specific intermolecular interactions including chalcogen-type interactions. The experimental electron density distribution was determined by high-angle X-ray diffraction. The atoms in molecules (AIM) theory was applied to analyze the charge density topology for a better characterization of intermolecular interactions present in the crystal.

The title compound, C24H31NO3 {systematic name: (E)-3-[(1R*,2S*,4aS*,8aR*)-2-(benzo[d][1,3]dioxol-5-yl)-1,2,4a,5,6,7,8,8a-octa-hydro-naphthalen-1-yl]-N-iso-butyl-acryl-amide}, is a natural product isolated from the stem bark of B. obscura. It is composed of an octa-hydro-naphthalene ring system substituted with an essentially planar benzodioxole ring system [r.m.s. deviation = 0.012 Å] and an extended iso-butyl-acryl-amide group. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains propagating along [100]. The chains are linked by pairs of C-H⋯O hydrogen bonds, involving inversion-related benzodioxole ring systems, forming ribbons lying parallel to (010). There are also C-H⋯π inter-actions present within the ribbons.

Deprotonation of the methylpyridines 2,6-lutidine, 2-picoline, 4-dimethylamino-2,6-dimethylpyridine as well as 2,6-dimethyl-4-(piperidine-1-yl)pyridine with n-butyllithium or n-butyllithium/KO-t-Bu at the methyl positions led to the corresponding organolithium or -potassium compounds. Treatment with ClB(C6F5)2 resulted in formation of the 2-borylmethylpyridines py-CH2-B(C6F5)2. They are monomeric and form intramolecular B-N bonds and four-membered rings. A short intramolecular B-N distance was observed in the crystal structure of the dimethylamino-functionalized derivative and proposed to be responsible for the low reactivity of the products towards hydrogen, thf, acetonitrile and CO2. Hydroboration of 6-tert-butyl-2-but-4'-enylpyridine with HB(C6F5)2 led to the corresponding hydroboration product t-Bu-py-(CH2)4-B(C6F5)2 which shows no intramolecular B-N bond formation due to steric crowding. H/D-scrambling experiments with a H2/D2 mixture revealed its reactivity towards hydrogen.

Two C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes, 1-(BMes2)-2-R-1,2-C2B10H10 (1, R = H, 2, R = Ph), were synthesised by lithiation of 1,2-dicarba-closo-dodecaborane and 1-phenyl-1,2-dicarba-closo-dodecaborane, respectively, with n-butyllithium and subsequent reaction with fluorodimesitylborane. These novel compounds were structurally characterised by X-ray crystallography. Compounds 1 and 2 are hydrolysed on prolonged exposure to air to give mesitylene and boronic acids 1-(B(OH)2)-2-R-1,2-C2B10H10 (3, R = H, 4, R = Ph respectively). Addition of fluoride anions to 1 and 2 resulted in boryl-carborane bond cleavage to give dimesitylborinic acid HOBMes2. UV absorption bands at 318-333 nm were observed for 1 and 2 corresponding to local π-π*-transitions within the dimesitylboryl groups while visible emissions at 541-664 nm with Stokes shifts of 11 920-16 170 cm(-1) were attributed to intramolecular charge transfer transitions between the mesityl and cluster groups. Compound was shown by cyclic voltammetry to form a stable dianion on reduction. NMR spectra for the dianion [](2-) were recorded from solutions generated by reductions of 2 with alkali metals and compared with NMR spectra from reductions of 1,2-diphenyl-ortho-carborane 5. On the basis of observed and computed (11)B NMR shifts, these nido-dianions contain bowl-shaped cluster geometries. The carborane is viewed as the electron-acceptor and the mesityl group is the electron-donor in C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes.

To investigate the geometry and stereochemical activity of the lone pair at the lead atom, lead(ii) complexes () with one tripodal (L(1)), one dipodal (L(2)) boron-centred soft ligand and eight other small soft heterocyclic ligands, 2-mercaptobenzimidazole (L(3)), 2-mercapto-5-methylbenzimidazole (L(4)), 3-mercapto-1,2,4-triazole (L(5)H), 3-mercapto-4-methyl-1,2,4-triazole (L(6)), 2-mercapto-1,3,4-thiadiazole (L(7)H), 2-mercapto-5-methyl-1,3,4-thiadiazole (L(8)H), 5-mercapto-1-methyltetrazole (L(9)H) and 2-mercapto-4-phenylthiazole (L(10)H) were prepared. The structures of these complexes were elucidated on the basis of X-ray crystallography, elemental analyses as well as (1)H NMR, (1)H DOSY, (13)C NMR and (207)Pb NMR spectroscopy. The coordination numbers of these complexes vary from 4 to 8. The majority of the complexes are polymeric and possess a hemi-directed environment around the lead atoms. Solution studies revealed that most of the complexes are dissociated in highly polar solvents. Most of the complexes are emissive both under ambient conditions and at 77 K in the solid state. However, no obvious relationship between their solid state structures and luminescence behaviour with respect to the nature of the excited state could be identified.

The addition of BCl3 to the carbene-transfer reagent NHC→SiCl4 (NHC=1,3-dimethylimidazolidin-2-ylidene) gave the tetra- and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl3 ](+) and [(NHC)2 SiCl3 ](+) with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHC→SiCl4 served as a transfer reagent for the NHC ligand. The addition of BF3 ⋅OEt2 , on the other hand, gave NHC→BF3 as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl)silane (C2 F5 )2 SiCl2 was treated with NHC→SiCl4 . In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl3 ](+) and [(NHC)2 SiCl3 ](+) were detected with [(C2 F5 )SiCl3 ](-) as counterion. A similar result was already reported for the reaction of NHC→SiCl4 with (C2 F5 )2 SiH2 , which gave [(NHC)2 SiCl2 H][(C2 F5 )SiCl3 ]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHC→Si(C2 F5 )2 Cl2 and NHC→Si(C2 F5 )2 ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron-poor silylenes. Furthermore, the reactivity of NHC→SiCl4 towards phosphines is discussed. The carbene complex NHC→PCl3 shows similar reactivity to NHC→SiCl4 , and may even serve as a carbene-transfer reagent as well., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Chlorosilicates represent important intermediates in S(N)2 reactions of chlorosilanes. They can be stabilized by the introduction of electron-withdrawing substituents. Salts of various (pentafluoroethyl)chlorosilicates have been isolated and structurally characterized., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The syntheses of Na(Ttt(Me)) (), K(Ttt(Me)) (), K(Btt(Me)) (), and Na(Btt(Ph)) () are reported, where (Ttt(Me))(-) and (Btt(R))(-) (R = Me, Ph) are tri- and di-substituted boron-centered soft ligands; they were produced by the reaction of NaBH4 and KBH4 with the corresponding tetrazole heterocycles: 1-methyl-5-thiotetrazole (L(1)H) and 1-phenyl-5-thiotetrazole (L(2)H). The syntheses of Na(Ttt(Me)) () and K(Ttt(Me)) () were carried out following Trofimenko's protocol. The anion (Ttt(Me))(-) is a typical Janus scorpionate ligand. Na(Ttt(Me)) () and Na(Btt(Ph)) () were reacted with Bi(CH3COO)3 to observe the coordination pattern of these ligands towards bismuth ions. These reactions afforded the complexes [Bi(Ttt(Me))2(CH3COO)] (), [Bi(L(2))2]2 (, ) and [Bi(L(2))3] (). The products were characterized by NMR spectroscopy, elemental analyses and mass spectrometry. Solid state structures were determined by X-ray diffraction of single crystals of , , , , , , and . M(Ttt(Me)) (M = Na (), K ()) and K(Btt(Me)) () exhibit sheet-like structures. The alkali metal complexes dissociate in solution as observed in (1)H, (13)C NMR and (1)H diffusion NMR experiments. Negative mode ESI-MS data also indicate the presence of monomers. Both the sodium salts of (Ttt(Me))(-) and (Btt(Ph))(-) as well as the Bi complexes and were investigated by absorption and emission spectroscopy.

Lithium carbenoids are versatile compounds for synthesis owing to their intriguing ambiphilic behavior. Although this class of compounds has been known for several years, few solid-state structures exist because of their high reactivity and often low thermal stability. Using cryo X-ray techniques, we were now able to elucidate the first solid-state structure of a Li/F alkyl carbenoid, pentafluoroethyllithium (LiC2F5), finally yielding a prototype for investigating structure-reactivity relationships for this class of molecules. The compound forms a diethyl ether-solvated dimer bridged by a rare C-F-Li link. Complementary NMR spectroscopy studies in solution show dynamic processes and indicate rapid exchange of starting material and product. Theoretical investigations help to understand the formation of the observed unusual structural motif., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)