TY  - JOUR
A1  - Föhrenbacher, Steffen A.
A1  - Krahfuss, Mirjam J.
A1  - Zapf, Ludwig
A1  - Friedrich, Alexandra
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
A1  - Radius, Udo
T1  - Tris(pentafluoroethyl)difluorophosphorane: a versatile fluoride acceptor for transition metal chemistry
JF  - Chemistry Europe
N2  - Fluoride abstraction from different types of transition metal fluoride complexes [L\(_n\)MF] (M=Ti, Ni, Cu) by the Lewis acid tris(pentafluoroethyl)difluorophosphorane (C\(_2\)F\(_5\))\(_3\)PF\(_2\) to yield cationic transition metal complexes with the tris(pentafluoroethyl)trifluorophosphate counterion (FAP anion, [(C\(_2\)F\(_5\))\(_3\)PF\(_3\)]\(^-\)) is reported. (C\(_2\)F\(_5\))\(_3\)PF\(_2\) reacted with trans-[Ni(iPr\(_2\)Im)\(_2\)(Ar\(^F\))F] (iPr2Im=1,3-diisopropylimidazolin-2-ylidene; Ar\(^F\)=C\(_6\)F\(_5\), 1 a; 4-CF\(_3\)-C\(_6\)F\(_4\), 1 b; 4-C\(_6\)F\(_5\)-C\(_6\)F\(_4\), 1 c) through fluoride transfer to form the complex salts trans-[Ni(iPr\(_2\)Im)\(_2\)(solv)(Ar\(^F\))]FAP (2 a-c[solv]; solv=Et\(_2\)O, CH\(_2\)Cl\(_2\), THF) depending on the reaction medium. In the presence of stronger Lewis bases such as carbenes or PPh\(_3\), solvent coordination was suppressed and the complexes trans-[Ni(iPr\(_2\)Im)\(_2\)(PPh\(_3\))(C\(_6\)F\(_5\))]FAP (trans-2 a[PPh\(_3\)]) and cis-[Ni(iPr\(_2\)Im)\(_2\)(Dipp\(_2\)Im)(C\(_6\)F\(_5\))]FAP (cis-2 a[Dipp\(_2\)Im]) (Dipp\(_2\)Im=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were isolated. Fluoride abstraction from [(Dipp\(_2\)Im)CuF] (3) in CH\(_2\)Cl\(_2\) or 1,2-difluorobenzene led to the isolation of [{(Dipp\(_2\)Im)Cu}\(_2\)]\(^2\)\(^+\)2 FAP\(^-\) (4). Subsequent reaction of 4 with PPh\(_3\) and different carbenes resulted in the complexes [(Dipp\(_2\)Im)Cu(LB)]FAP (5 a–e, LB=Lewis base). In the presence of C6Me6, fluoride transfer afforded [(Dipp\(_2\)Im)Cu(C\(_6\)Me\(_6\))]FAP (5 f), which serves as a source of [(Dipp\(_2\)Im)Cu)]\(^+\). Fluoride abstraction of [Cp\(_2\)TiF\(_2\)] (7) resulted in the formation of dinuclear [FCp\(_2\)Ti(μ-F)TiCp\(_2\)F]FAP (8) (Cp=η\(^5\)-C\(_5\)H\(_5\)) with one terminal fluoride ligand at each titanium atom and an additional bridging fluoride ligand.
KW  - inorganic chemistry
KW  - copper
KW  - nickel
KW  - phosphoranes
KW  - titanium
KW  - weakly coordinating anions
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256665
VL  - 27
IS  - 10
ER  - 
TY  - JOUR
A1  - Föhrenbacher, Steffen A.
A1  - Zeh, Vivien
A1  - Krahfuss, Mirjam J.
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
A1  - Radius, Udo
T1  - Tris(pentafluoroethyl)difluorophosphorane and N‐Heterocyclic Carbenes: Adduct Formation and Frustrated Lewis Pair Reactivity
JF  - European Journal of Inorganic Chemistry
N2  - The synthesis and characterization of Lewis acid/base adducts between tris(pentafluoroethyl)difluorophosphorane PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\) and selected N-heterocyclic carbenes (NHCs) R\(_{2}\)Im (1,3-di-organyl-imidazolin-2-ylidene) and phosphines are reported. For NHCs with small alkyl substituents at nitrogen (R=Me, nPr, iPr) the adducts NHC ⋅ PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\) (2 a–h) were isolated. The reaction with the sterically more demanding NHCs Dipp\(_{2}\)Im (1,3-bis-(2,6-di-iso-propylphenyl)-imidazolin-2-ylidene) (1 i) and tBu\(_{2}\)Im (1,3-di-tert-butyl-imidazolin-2-ylidene) (1 j) afforded the aNHC adducts 3 i and 3 j (a denotes “abnormal” NHC coordination via a backbone carbon atom). The use of tBuMeIm (1-tert-butyl-3-methyl-imidazolin-2-ylidene) (1 m) led to partial decomposition of the NHC and formation of the salt [tBuMeIm−H][MeIm ⋅ PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\)] (4 m). The phosphorane PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\) forms adducts with PMe\(_{3}\) but does not react with PPh\(_{3}\) or PCy\(_{3}\). The mer-cis isomer of literature-known Me\(_{3}\)P ⋅ PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\) (5 a) was structurally characterized. Mixtures of the phosphorane PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\) and the sterically encumbered NHCs tBu\(_{2}\)Im, Dipp\(_{2}\)Im, and Dipp\(_{2}\)Im\(^{H2}\) (1,3-bis-(2,6-di-iso-propylphenyl)-imidazolidin-2-ylidene) (1 k) showed properties of FLPs (Frustrated Lewis Pairs) as these mixtures were able to open the ring of THF (tetrahydrofuran) to yield NHC−(CH\(_{2}\))\(_{4}\)O−PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\) 6 i–k. Furthermore, the deprotonation of the weak C−H acids CH\(_{3}\)CN, acetone, and ethyl acetate was achieved, which led to the formation of the corresponding imidazolium salts and the phosphates [PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\)(CH\(_{2}\)CN)]\(^{-}\) (7), [PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\)(OC(=CH\(_{2}\))CH\(_{3}\))]\(^{-}\) (8) and [PF\(_{2}\)(C\(_{2}\)F\(_{5}\))\(_{3}\)(CH\(_{2}\)CO\(_{2}\)Et)]\(^{-}\) (9).
KW  - C-H activation
KW  - N-Heterocyclic Carbene Adducts
KW  - N-Heterocyclic Carbenes
KW  - Frustrated Lewis Pairs
KW  - Fluoro(perfluoroalkyl) phosphoranes
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257386
VL  - 2021
IS  - 20
ER  - 
TY  - JOUR
A1  - Schneider, Leon N.
A1  - Tanzer Krauel, Eva-Maria
A1  - Deutsch, Carl
A1  - Urbahns, Klaus
A1  - Bischof, Tobias
A1  - Maibom, Kristina A. M.
A1  - Landmann, Johannes
A1  - Keppner, Fabian
A1  - Kerpen, Christoph
A1  - Hailmann, Michael
A1  - Zapf, Ludwig
A1  - Knuplez, Tanja
A1  - Bertermann, Rüdiger
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
T1  - Stable and Storable N(CF\(_{3}\))\(_{2}\) Transfer Reagents
JF  - Chemistry—A European Journal
N2  - Fluorinated groups are essential for drug design, agrochemicals, and materials science. The bis(trifluoromethyl)amino group is an example of a stable group that has a high potential. While the number of molecules containing perfluoroalkyl, perfluoroalkoxy, and other fluorinated groups is steadily increasing, examples with the N(CF\(_{3}\))\(_{2}\) group are rare. One reason is that transfer reagents are scarce and metal-based storable reagents are unknown. Herein, a set of Cu\(^{I}\) and Ag\(^{I}\) bis(trifluoromethyl)amido complexes stabilized by N- and P-donor ligands with unprecedented stability are presented. The complexes are stable solids that can even be manipulated in air for a short time. They are bis(trifluoromethyl)amination reagents as shown by nucleophilic substitution and Sandmeyer reactions. In addition to a series of benzylbis(trifluoromethyl)amines, 2-bis(trifluoromethyl)amino acetate was obtained, which, upon hydrolysis, gives the fluorinated amino acid N,N-bis(trifluoromethyl)glycine.
KW  - silver
KW  - amination
KW  - copper
KW  - fluorinated ligands
KW  - N ligands
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256890
VL  - 27
IS  - 42
ER  - 
TY  - JOUR
A1  - Bischoff, Lisa A.
A1  - Riefer, Jarno
A1  - Wirthensohn, Raphael
A1  - Bischof, Tobias
A1  - Bertermann, Rüdiger
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
T1  - Pentafluoroethylaluminates: A Combined Synthetic, Spectroscopic, and Structural Study
JF  - Chemistry – A European Journal
N2  - Salts of the tetrakis(pentafluoroethyl)aluminate anion [Al(C\(_{2}\)F\(_{5}\))\(_{2}\)]\(^{-}\) were obtained from AlCl\(_{3}\) and LiC\(_{2}\)F\(_{5}\). They were isolated with different counter‐cations and characterized by NMR and vibrational spectroscopy and mass spectrometry. Degradation of the [Al(C\(_{2}\)F\(_{5}\))\(_{4}\)]\(^{-}\) ion was found to proceed via 1,2‐fluorine shifts and stepwise loss of CF(CF\(_{3}\)) under formation of [(C\(_{2}\)F\(_{5}\))\(_{4-n}\)AlF\(_{n}\)]− (n=1–4) as assessed by NMR spectroscopy and mass spectrometry and supported by results of DFT calculations. In addition, the [(C\(_{2}\)F\(_{5}\))AlF\(_{3}\)]\(^{-}\) ion was structurally characterized.
KW  - aluminum
KW  - fluorine
KW  - perfluoroalkyl
KW  - weakly coordinating anions
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214666
VL  - 26
IS  - 60
SP  - 13615
EP  - 13620
ER  - 
TY  - JOUR
A1  - Drisch, Michael
A1  - Bischoff, Lisa A.
A1  - Sprenger, Jan A. P.
A1  - Hennig, Philipp T.
A1  - Wirthensohn, Raphael
A1  - Landmann, Johannes
A1  - Konieczka, Szymon Z.
A1  - Hailmann, Michael
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
T1  - Innovative Syntheses of Cyano(fluoro)borates: Catalytic Cyanation, Electrochemical and Electrophilic Fluorination
JF  - Chemistry – A European Journal
N2  - Different types of high‐yield, easily scalable syntheses for cyano(fluoro)borates Kt[BF\(_{n}\)(CN)\(_{4-n}\)] (n=0–2) (Kt=cation), which are versatile building blocks for materials applications and chemical synthesis, have been developed. Tetrafluoroborates react with trimethylsilyl cyanide in the presence of metal‐free Brønsted or Lewis acid catalysts under unprecedentedly mild conditions to give tricyanofluoroborates or tetracyanoborates. Analogously, pentafluoroethyltrifluoroborates are converted into pentafluoroethyltricyanoborates. Boron trifluoride etherate, alkali metal salts, and trimethylsilyl cyanide selectively yield dicyanodifluoroborates or tricyanofluoroborates. Fluorination of cyanohydridoborates is the third reaction type that includes direct fluorination with, for example, elemental fluorine, stepwise halogenation/fluorination reactions, and electrochemical fluorination (ECF) according to the Simons process. In addition, fluorination of [BH(CN)\(_{2}\){OC(O)Et}]\(^{-}\) to result in [BF(CN)\(_{2}\){OC(O)Et}]\(^{-}\) is described.
KW  - cyanoborates
KW  - electrochemical fluorination
KW  - fluorination
KW  - fluoroborates
KW  - ionic liquids
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-216027
VL  - 26
IS  - 50
SP  - 11625
EP  - 11633
ER  - 
TY  - JOUR
A1  - Landmann, Johannes
A1  - Hennig, Philipp T.
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
T1  - Borylation of fluorinated arenes using the boron centred nucleophile B(CN)\(_{3}\)\(^{2-}\) - a unique entry to aryltricyanoborates
JF  - Chemical Science
N2  - The potassium salt of the boron-centred nucleophile B(CN)\(_{3}\)\(^{2-}\)(1) readily reacts with perfluorinated arenes, such as hexafluorobenzene, decafluorobiphenyl, octafluoronaphthalene and pentafluoropyridine, which results in KF and the K\(^{+}\) salts of the respective borate anions with one {B(CN)\(_{3}\)} unit bonded to the (hetero)arene. An excess of K\(_{2}\)1 leads to the successive reaction of two or, in the case of perfluoropyridine, even three C–F moieties and the formation of di- and trianions, respectively. Moreover, all of the 11 partially fluorinated benzene derivatives, C\(_{6}\)F\(_{6-n}\)H\(_{n}\) (n = 1–5), generally react with K\(_{2}\)1 to give new tricyano(phenyl)borate anions with high chemo- and regioselectivity. A decreasing number of fluorine substituents on benzene results in a decrease in the reaction rate. In the cases of partially fluorinated benzenes, the addition of LiCl is advantageous or even necessary to facilitate the reaction. Also, pentafluorobenzenes R–C\(_{6}\)F\(_{5}\) (R = –CN, –OMe, –Me, or –CF\(_{3}\)) react via C–F/C–B exchange that mostly occurs in the para position and to a lesser extent in the meta or ortho positions. Most of the reactions proceed via an S\(_{N}\)Ar mechanism. The reaction of 1,4-F\(_{2}\)C\(_{6}\)H\(_{4}\) with K\(_{2}\)1 shows that an aryne mechanism has to be considered in some cases as well. In summary, a wealth of new stable tricyano(aryl)borates have been synthesised and fully characterized using multi-NMR spectroscopy and most of them were characterised using single-crystal X-ray diffraction.
KW  - borylation
KW  - boron-centred nucleophile
KW  - aryltricyanoborates
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170417
VL  - 8
IS  - 9
ER  - 
TY  - JOUR
A1  - Huang, Zhenguo
A1  - Wang, Suning
A1  - Dewhurst, Rian D.
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
A1  - Braunschweig, Holger
T1  - Boron: Its Role in Energy‐Related Processes and Applications
JF  - Angewandte Chemie International Edition
N2  - Boron's unique position in the Periodic Table, that is, at the apex of the line separating metals and nonmetals, makes it highly versatile in chemical reactions and applications. Contemporary demand for renewable and clean energy as well as energy‐efficient products has seen boron playing key roles in energy‐related research, such as 1) activating and synthesizing energy‐rich small molecules, 2) storing chemical and electrical energy, and 3) converting electrical energy into light. These applications are fundamentally associated with boron's unique characteristics, such as its electron‐deficiency and the availability of an unoccupied p orbital, which allow the formation of a myriad of compounds with a wide range of chemical and physical properties. For example, boron's ability to achieve a full octet of electrons with four covalent bonds and a negative charge has led to the synthesis of a wide variety of borate anions of high chemical and electrochemical stability—in particular, weakly coordinating anions. This Review summarizes recent advances in the study of boron compounds for energy‐related processes and applications.
KW  - boron
KW  - electrolytes
KW  - hydrogen
KW  - OLEDs
KW  - small-molecule activation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218514
VL  - 59
IS  - 23
SP  - 8800
EP  - 8816
ER  -