Mesoionic dithiolates (MIDtAr)Li(LiBr)2(THF)3 (MIDtAr={SC(NDipp)}2CAr; Dipp=2,6‐iPr2C6H3; Ar=Ph 3 a, 3‐MeC6H4 (3‐Tol) 3 b, 4‐Me2NC6H4 (DMP) 3 c) and (MIDtPh)Li(THF)2 (4) are readily accessible (in≥90 ...% yields) as crystalline solids on treatments of anionic dicarbenes Li(ADCAr) (2 a‐c) (ADCAr={C(NDipp)2}2CAr) with elemental sulfur. 3 a‐c and 4 are monoanionic ditopic ligands with both the sulfur atoms formally negatively charged, while the 1,3‐imidazole unit bears a formal positive charge. Treatment of 4 with (L)GeCl2 (L=1,4‐dioxane) affords the germylene (MIDtPh)GeCl (5) featuring a three‐coordinated Ge atom. 5 reacts with (L)GeCl2 to give the Ge−Ge catenation product (MIDtPh)GeGeCl3 (6). KC8 reduction of 5 yields the homoleptic germylene (MIDtPh)2Ge (7). Compounds 3 a‐c and 4–7 have been characterized by spectroscopic studies and single‐crystal X‐ray diffraction. The electronic structures of 4–7 have been analyzed by DFT calculations.
Mesoionic dithiolates Li(MIDts) as well as heteroleptic (MIDt)GeCl and homoleptic (MIDt)2Ge germylenes are reported as crystalline solids. The germylene (MIDt)2Ge features the highest‐lying HOMO (−4.37 eV) and has the smallest HOMO‐LUMO energy gap (2.82 eV) among the hitherto known germylenes. Insertion of GeCl2 into the Ge−Cl bond of (MIDt)GeCl affords the Ge−Ge catenation product (MIDt)GeGeCl3, a mixed‐valence Ge(+1)/Ge(+3) compound.
Abstract Lewis superacids (LSA) are defined by a fluoride ion affinity (FIA) that exceeds that of SbF 5 , and are thus characterized as hard according to the HSAB concept. Soft superacidity was ...defined for compounds exceeding the hydride ion affinity (HIA) of B(C 6 F 5 ) 3 . Herein we report on the synthesis of a Lewis acid being superacidic only on the soft regime: tris(pentafluoroethyl)indane, In(C 2 F 5 ) 3 . It is accessible in the form of its dihydrate In(C 2 F 5 ) 3 (OH 2 ) 2 . An improved synthesis for the gallium analogue Ga(C 2 F 5 ) 3 (OH 2 ) 2 is also reported. Tris(pentafluoroethyl)indane dihydrate, In(C 2 F 5 ) 3 (OH 2 ) 2 , was fully characterized by IR and NMR spectroscopy, as well as by single crystal X‐ray diffraction. Due to their stability and convenient accessibility, the hydrates are ideal starting compounds for the chemistry of tris(pentafluoroethyl)gallium and ‐indium compounds, for example hydroxogallates and ‐indates. An attempt to determine its gas‐phase structure and that of the gallium analogue by electron diffraction demonstrates that they lose water ligands upon evaporation. The energetics of these processes were predicted by quantum‐chemical calculations as was the nature of bonding in the free Lewis acids and their mono‐ and dihydrates. Furthermore, the synthesis and structural diversity of hydroxido tris(pentafluoroethyl) gallates and one indate are presented.
Supporting information: Additional Supporting Information may be found in the online version of this article As a service to our authors and readers, this journal provides supporting information ...supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. CAPTION(S): Supplementary Byline: Timo Glodde, Yury V. Vishnevskiy, Lars Zimmermann, Hans-Georg Stammler, Beate Neumann, Norbert W. Mitzel
The structures of the three para‐substituted halotetrafluoropyridines with chlorine, bromine, and iodine have been determined in the solid state (X‐ray diffraction). The structures of these compounds ...and that of pentafluoropyridine were also determined in the gas phase (electron diffraction). Structures in the solid state of the bromine and iodine derivatives exhibit halogen bonding as a structure‐determining motif. On the way to an investigation of halogen bond formation of halotetrafluoropyridines in the solid state with the stronger Lewis base pyridine, co‐crystals of benzene adducts were investigated to gain an understanding of the influence of aryl–aryl interactions. These co‐crystals showed halogen bonding only for the two heavier halotetrafluoropyridines. In the pyridine co‐crystals halogen bonding was observed for all three para‐halotetrafluoropyridines. The formation of homodimers and heterodimers with pyridine is also supported by quantum‐chemical calculations of electron density topologies and natural bond orbitals.
Halogen‐bond formation in co‐crystals containing halogentetrafluoropyridines is markedly dependent on the type of halogen atom, the electronegativity of its substituent, and the halogen bond acceptor and it is less pronouncedly dependent on additional π–π stacking interactions.
Accuracy and precision of molecular parameters determined by modern gas electron diffraction have been investigated. Diffraction patterns of gaseous pyrazinamide have been measured independently in ...three laboratories, in Bielefeld (Germany), Ivanovo (Russia), and Moscow (Russia). All data sets have been analyzed in equal manner using a highly controlled background elimination procedure and flexible restraints in molecular structure refinement. In detailed examination and comparison of the obtained results we have determined the average experimental precision of 0.004 Å for bond lengths and 0.2° for angles. The corresponding average deviations of the refined parameters from the ae-CCSD(T)/cc-pwCVTZ theoretical values were 0.003 Å and 0.2°. The average precision for refined amplitudes of interatomic vibrations was determined to be 0.005 Å. It is recommended to take into account these values in calculations of total errors for refined parameters of other molecules with comparable complexity.
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.
Despite its explosive nature, crystals of the Li/F alkyl carbenoid pentafluoroethyllithium LiC2F5 could be isolated and the first experimental structure of its ether adduct determined. This structure clarifies earlier speculations on structure–reactivity relationships in carbenoid chemistry.
An improved synthesis of the simplest nitric acid ester, methyl nitrate, and a new synthesis of fluoromethyl nitrate use the metathesis of the corresponding iodomethanes with silver nitrate. Both ...compounds were identified by spectroscopy and the structures determined for in situ grown crystals by X‐ray diffraction as well as in the gas phase by electron diffraction. Fluorination leads to structures with shorter C−O and N−O bonds, has an energetically destabilizing effect and increases friction sensitivity, but decreases detonation performance.
Six centuries after the discovery of the simplest nitric acid ester, methyl nitrate (H3CONO2), experimental solid‐state and gas‐phase structures as well as energetic properties are compared with those of the new monofluorine‐substituted analogue, fluoromethyl nitrate (FH2CONO2).
Gas-phase structures of two isomers of dimethyl-substituted 1,5-diazabicyclo3.1.0hexanes, namely, 3,3-dimethyl- and 6,6-dimethyl-1,5-diazabicyclo3.1.0hexane molecules, have been determined by gas ...electron diffraction method. A new approach based on the Monte Carlo method has been developed and used for the analysis of precision and accuracy of the refined structures. It was found that at 57 °C 3,3-dimethyl derivative exists as a mixture of chair and boat conformers with abundances 68(8)% and 32(8)%, respectively. 6,6-Dimethyl-1,5-diazabicyclo3.1.0hexane at 50 °C has only one stable conformation with planar 5-ring within error limits. Theoretical calculations predict that the 6,6-dimethyl isomer is more stable in comparison to the 3,3-dimethyl isomer with energy difference 3–5 kcal mol–1. In order to explain the relative stability and bonding properties of different structures the natural bond orbitals (NBO), atoms in molecules (AIM), and interacting quantum atoms (IQA) analyses were performed.
Starting from ferrocene, pentafluoroferrocene Fe(C5F5)(C5H5) can be prepared in five steps via a one-pot lithiation–electrophilic fluorination strategy. Pentafluoroferrocene was characterized by ...multinuclear NMR and IR spectroscopy, by cyclovoltammetry as well as X-ray (solid) and electron diffraction (gas) and the experimental results compared with DFT calculations.
Decarbonylation of a cyclic bis-phosphaethynolatostannylene (ADC)Sn(PCO)
based on an anionic dicarbene framework (ADC = PhC{N(Dipp)C}
; Dipp = 2,6-iPr
C
H
) under UV light results in the formation of ...a Sn
P
cluster compound (ADC)SnP
as a green crystalline solid. The electronic structure of (ADC)SnP
is analyzed by quantum-chemical calculations. At room temperature, (ADC)SnP
reversibly binds with CO
and forms (ADC)
{SnOC(O)P}SnP. (ADC)SnP
enables catalytic hydroboration of CO
and reacts with elemental selenium and Fe
(CO)
to afford (ADC)
{Sn(Se)P
}SnSe and (ADC)Sn{Fe(CO)
}P
, respectively. All compounds are characterized by multinuclear NMR spectroscopy and their solid-state molecular structures are determined by single-crystal X-ray diffraction.
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