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  • 1
    Online Resource
    Online Resource
    Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry
    Wiley ; 2021
    In:  Chemistry – A European Journal Vol. 27, No. 10 ( 2021-02-15), p. 3504-3516
    Details
    In: Chemistry – A European Journal, Wiley, Vol. 27, No. 10 ( 2021-02-15), p. 3504-3516
    Abstract: 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( i Pr 2 Im) 2 (Ar F )F] ( i Pr 2 Im=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( i Pr 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( i Pr 2 Im) 2 (PPh 3 )(C 6 F 5 )] FAP ( trans ‐2 a[PPh 3 ] ) and cis ‐[Ni( i Pr 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 C 6 Me 6 , 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.
    Type of Medium: Online Resource
    ISSN: 0947-6539 , 1521-3765
    URL: Issue
    URL: Article
    DOI: 10.1002/chem.v27.10
    DOI: 10.1002/chem.202004885
    RVK:
    VA 1120 ; VA 3507
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 1478547-X
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  • 2
    Online Resource
    Online Resource
    Tris(pentafluoroethyl)difluorophosphorane and N ‐Heterocyclic Carbenes: Adduct Formation and Frustrated Lewis Pair Reactivity
    Wiley ; 2021
    In:  European Journal of Inorganic Chemistry Vol. 2021, No. 20 ( 2021-05-26), p. 1941-1960
    Details
    In: European Journal of Inorganic Chemistry, Wiley, Vol. 2021, No. 20 ( 2021-05-26), p. 1941-1960
    Abstract: 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, n Pr, i Pr) 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 t Bu 2 Im (1,3‐di‐ tert ‐butyl‐imidazolin‐2‐ylidene) ( 1 j ) afforded the a NHC adducts 3 i and 3 j ( a denotes “abnormal” NHC coordination via a backbone carbon atom). The use of t BuMeIm (1‐ tert ‐butyl‐3‐methyl‐imidazolin‐2‐ylidene) ( 1 m ) led to partial decomposition of the NHC and formation of the salt [ t BuMeIm−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 t Bu 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 ).
    Type of Medium: Online Resource
    ISSN: 1434-1948 , 1099-0682
    URL: Issue
    URL: Article
    DOI: 10.1002/ejic.v2021.20
    DOI: 10.1002/ejic.202100183
    RVK:
    VA 4072.5
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 1475009-0
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  • 3
    Online Resource
    Online Resource
    An Investigation of the Symmetric and Asymmetric Cleavage Products in the System Aluminum Trihalide/1‐Butylimidazole
    Wiley ; 2017
    In:  Chemistry – A European Journal Vol. 23, No. 46 ( 2017-08-16), p. 11054-11066
    Details
    In: Chemistry – A European Journal, Wiley, Vol. 23, No. 46 ( 2017-08-16), p. 11054-11066
    Abstract: Mixtures of AlX 3 (X=Cl, Br) with 1‐butylimidazole (BuIm) in various ratios were investigated. The mixtures were characterized by multinuclear ( 1 H, 27 Al, 13 C, and 15 N) NMR, IR, and Raman spectroscopy and in part by single‐crystal X‐ray diffraction. Depending on the molar fraction x (AlBr 3 ) of the AlBr 3 ‐based mixtures, the cationic aluminum complexes [Al(BuIm) 6 ] 3+ and [AlBr 2 (BuIm) 4 ] + , the neutral adduct [AlBr 3 (BuIm)], as well as the anions Br − , [AlBr 4 ] − , and [Al 2 Br 7 ] − could be identified as the products of the symmetric and asymmetric cleavage of dimeric Al 2 Br 6 . Furthermore, there are hints at the formation of [AlBr 2 (BuIm) 2 ] + or related cations. Comparison of the AlBr 3 /BuIm system with AlCl 3 ‐based mixtures revealed the influence of the halide: In contrast to AlBr 3 , the trication [Al(BuIm) 6 ] 3+ could not be detected as main product in a 1:6 mixture of AlCl 3 and BuIm. Additionally, [AlCl 3 (BuIm)] crystallizes from a mixture with x (AlCl 3 )=0.60 at room temperature, whereas the corresponding AlBr 3 ‐based mixture remains liquid even at +6 °C. Three AlBr 3 ‐based mixtures are liquid at room temperature, whereas all other mixtures are solids with melting points between 46 and 184 °C. The three liquid mixtures exhibit medium to high viscosities (117 to 〉 1440 mPa s), low conductivities (0.03–0.20 mS cm −1 ), but high densities (1.80–2.21 g cm −3 ). Aluminum could be successfully deposited from one of the neat Lewis acidic mixtures of the AlBr 3 ‐based system.
    Type of Medium: Online Resource
    ISSN: 0947-6539 , 1521-3765
    URL: Issue
    URL: Article
    DOI: 10.1002/chem.v23.46
    DOI: 10.1002/chem.201701553
    RVK:
    VA 1120 ; VA 3507
    Language: English
    Publisher: Wiley
    Publication Date: 2017
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  • 4
    Online Resource
    Online Resource
    An easy-to-perform evaluation of steric properties of Lewis acids
    Royal Society of Chemistry (RSC) ; 2023
    In:  Chemical Science Vol. 14, No. 9 ( 2023), p. 2275-2288
    Details
    In: Chemical Science, Royal Society of Chemistry (RSC), Vol. 14, No. 9 ( 2023), p. 2275-2288
    Abstract: Steric and electronic effects play a very important role in chemistry, as these effects influence the shape and reactivity of molecules. Herein, an easy-to-perform approach to assess and quantify steric properties of Lewis acids with differently substituted Lewis acidic centers is reported. This model applies the concept of the percent buried volume (% V Bur ) to fluoride adducts of Lewis acids, as many fluoride adducts are crystallographically characterized and are frequently calculated to judge fluoride ion affinities (FIAs). Thus, data such as cartesian coordinates are often easily available. A list of 240 Lewis acids together with topographic steric maps and cartesian coordinates of an oriented molecule suitable for the SambVca 2.1 web application is provided, together with different FIA values taken from the literature. Diagrams of % V Bur as a scale for steric demand vs. FIA as a scale for Lewis acidity provide valuable information about stereo-electronic properties of Lewis acids and an excellent evaluation of steric and electronic features of the Lewis acid under consideration. Furthermore, a novel LAB-Rep model (Lewis acid/base repulsion model) is introduced, which judges steric repulsion in Lewis acid/base pairs and helps to predict if an arbitrary pair of Lewis acid and Lewis base can form an adduct with respect to their steric properties. The reliability of this model was evaluated in four selected case studies, which demonstrate the versatility of this model. For this purpose, a user-friendly Excel spreadsheet was developed and is provided in the ESI, which works with listed buried volumes of Lewis acids % V Bur_LA and of Lewis bases % V Bur_LB , and no results from experimental crystal structures or quantum chemical calculations are necessary to evaluate steric repulsion in these Lewis acid/base pairs.
    Type of Medium: Online Resource
    ISSN: 2041-6520 , 2041-6539
    URL: Article
    DOI: 10.1039/D3SC00037K
    Language: English
    Publisher: Royal Society of Chemistry (RSC)
    Publication Date: 2023
    detail.hit.zdb_id: 2559110-1
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