Klaus Eichele Publication Abstracts 2022

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M. Widemann, S. Jeggle, M. Auer, K. Eichele, H. Schubert, C. P. Sindlinger, L. Wesemann: Hydridotetrylene [Ar*EH] (E = Ge, Sn, Pb) coordination at tantalum, tungsten, and zirconium Chem. Sci. 2022, 13, 3999-4009. DOI: 10.1039/D2SC00297C

In a reaction of tantalocene trihydride with the low valent aryl tin cation [ Ar*Sn(C₆H₆)][Al(OC{CF₃}₃)₄] (1a) the hydridostannylene complex [Cp₂TaH₂-Sn(H)Ar*][Al(OC{CF₃}₃)₄] (2) was synthesized. Hydride bridged adducts [Cp₂WH₂EAr*][Al(OC{CF₃}₃)₄] (E = Sn 3a, Pb 3b) were isolated as products of the reaction between Cp₂WH₂ and cations [Ar*E(C₆H₆)][Al(OC{CF₃}₃)₄] (E = Sn 1a, Pb 1b). The tin adduct 3a exhibits a proton migration to give the hydridostannylene complex [Cp₂W(H)=Sn(H)Ar*][Al(OC{CF₃}₃)₄] 4a. The cationic complex 4a is deprotonated at the tin atom in reaction with base ^MeNHC at 80 °C to give a hydrido-tungstenostannylene [Cp₂W(H)SnAr*] 5a. Reprotonation of metallostannylene 5a with acid [H(Et₂O)₂][BAr^F] provides an alternative route to hydridotetrylene coordination. Complex 4a adds hydride to give the dihydrostannyl complex [Cp₂W(H)-SnH₂Ar*] (7). With styrene 4a shows formation of a hydrostannylation product [Cp₂W(H)=Sn(CH₂CH₂Ph)Ar*][Al(OC{CF₃}₃)₄] (8). The lead adduct 3b was deprotonated with ^MeNHC to give plumbylene 5b [Cp₂W(H)PbAr*]. Protonation of 5b with [H(Et₂O)₂][Al(OC{CF₃}₃)₄] at -40 °C followed by low temperature NMR spectroscopy indicates a hydridoplumbylene intermediate [Cp₂W(H)=Pb(H)Ar*]⁺ (4b). Hydrido-tungstenotetrylenes of elements Ge (5c), Sn (5a) and Pb (5b) were also synthesized reacting the salt [Cp₂W(H)Li]₄ with organotetrylene halides. The metallogermylene [Cp₂W(H)GeAr*] (5c) shows an isomerization via 1,2-H-migration to give the hydridogermylene [Cp₂W=Ge(H)Ar*] (9), which is accelerated by addition of AIBN. 9 is at rt photochemically transferred back to 5c under light of a mercury vapor lamp. Zirconocene dihydride [Cp₂ZrH₂]₂ reacts with tin cation 1a to give the trinuclear hydridostannylene adduct 10 [({Cp₂Zr}₂{μ-H})(μ-H)₂μ-Sn(H)Ar*][Al(OC{CF₃}₃)₄]. Deprotonation of 10 was carried out using benzyl potassium to give neutral [({Cp₂Zr}₂{μ-H})(μ-H)μ-Sn(H)Ar*] (11). 11 was also obtained from the reaction of low valent tin hydride [Ar*SnH]₂ with two equivalents of [Cp₂ZrH₂]₂. The trihydride Ar*SnH₃ reacts with half of an equivalent of [Cp₂ZrH₂]₂ under evolution of hydrogen and formation of a dihydrostannyl complex 13 [Cp₂Zr(μ-H)SnH₂Ar*]₂ and with further equivalents of Ar*SnH₃ to give bis(hydridostannylene) complex [Cp₂Zr{Sn(H)Ar*}₂].

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M. Auer, F. Diab, K. Eichele, H. Schubert, L. Wesemann: Reactivity of organogermanium and organotin trihydrides Dalton Trans. 2022, 51, 5950-5961. DOI: 10.1039/D2DT00681B

The organogermanium and organotin trihydrides (TbbEH₃) [E = Ge (3), Sn (7)] with the Tbb substituent were synthesized by hydride substitution (Tbb = 2,6-[CH(SiMe₃)₂]₂-4-(t-Bu)C₆H₂). Deprotonation of the organoelement trihydrides 3 and 7 was studied in reaction with bases MeLi, BnK and LDA (Bn = benzyl, LDA = lithium diisopropylamide) to yield the deprotonation products (8-11) as lithium or potassium salts. Hydride abstraction from TbbSnH₃ using the trityl salt [Ph₃C][Al(OC{CF₃}₃)₄] gives the salt [TbbSnH₂][Al(OC{CF₃}₃)₄] (12) which was stabilized by thf donor ligands [TbbSnH₂(thf)₂] [Al(OC{CF₃}₃)₄] (13). Tintrihydride 7 reacts with trialkylamine Et₂MeN to give as the product of a reductive elimination of hydrogen the distannane (TbbSnH₂)₂ (14). Transfer of hydrogen was observed in reaction of trihydrides TbbEH₃ (E = Ge, Sn) and Ar*GeH₃ with N-heterocyclic carbene (NHC). The NHC adduct TbbSnH(^iPrNHC) (15) was synthesized at rt and the germanium hydrides exhibit hydrogen transfer at higher temperatures to give Ar*GeH(^MeNHC) (16) and TbbGeH(^MeNHC) (17).

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M. Widemann, F. S. W. Aicher, M. Bonath, K. Eichele, C. Maichle-Mössmer, H. Schubert, P. Sirsch, R. Anwander, L. Wesemann, Molecular Ln(III)-H-E(II) Linkages (Ln = Y, Lu; E = Ge, Sn, Pb), Chem. Eur. J. 2022, e20221032. DOI: 10.1002/chem.202201032

Following the alkane-elimination route, the reaction between tetravalent aryl tintrihydride Ar*SnH₃ and trivalent rare-earth-metallocene alkyls [Cp*₂Ln(CH{SiMe₃}₂)] gave complexes [Cp*₂Ln(μ-H)₂SnAr*] implementing a low-valent tin hydride (Ln=Y, Lu; Ar*= 2,6-Trip₂C₆H₃, Trip= 2,4,6-triisopropylphenyl). The homologous complexes of germanium and lead, [Cp*₂Ln(μ-H)₂EAr*] (E = Ge, Pb), were accessed via addition of low-valent [(Ar*EH)₂] to the rare-earth-metal hydrides [(Cp*₂LnH)₂]. The lead compounds [Cp*₂Ln(μ-H)₂PbAr*] exhibit H/D exchange in reactions with deuterated solvents or dihydrogen.

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M. Auer, J. Bolten, K. Eichele, H. Schubert, C. P. Sindlinger, L. Wesemann Heavy Metalla Vinyl-Cations show Metal-Lewis Acid Cooperativity in Reaction with Small Molecules (NH3, N2H4, H2O, H2), Chem. Sci. 2022, accepted. DOI: 10.1039/D2SC05620H

Halide abstraction from tetrylidene complexes [TbbE(Br)IrH(PMe₃)₃] [E =Ge (1), Sn (2)] and [Ar*E(Cl)IrH(PMe₃)₃] gives the salts [TbbEIrH(PMe₃)₃][BArF₄] [E =Ge (3), Sn (4)] and [Ar*EIrH(PMe₃)₃][BArF₄] [E = Ge (3'), E = Sn (4')] (Tbb = 2,6-[CH(SiMe₃)₂]₂-4-(t-Bu)C₆H₂, Ar* = 2,6-Trip₂C₆H₃, Trip = 2,4,6-triisopropylphenyl). Bonding analysis suggests their most suitable description as metalla-tetrela vinyl cations with a Ir=E double bond and a near linear coordination at the Ge/Sn atoms. Cationic complexes 3 and 4 oxidatively add NH₃, N₂H₄, H₂O, HCl*Et₂O, and H₂ selectively to give: [TbbGe(NH₂)IrH₂(PMe₃)₃][BArF₄] (5), [TbbE(NHNH₂)IrH₂(PMe₃)₃][BArF₄] [E = Ge (7), Sn(8)], [TbbE(OH)IrH₂(PMe₃)₃][BArF₄] [E = Ge (9), Sn(10)], [TbbE(Cl)IrH₂(PMe₃)₃][BArF₄] [E = Ge (11a), Sn(12a)], [TbbGe(H)IrH₂(PMe₃)₃][BArF₄] (13), [TbbSn(μ-H₃)Ir(PMe₃)₃][BArF₄] (14), and [TbbSnHIrH₂(PMe₃)₃][BArF₄] (15). 14 isomerizes to give 15 via an 1,2-H shift reaction. Hydride addition to cation 3 gives a mixture of products [TbbGeHIrH(PMe₃)₃] (16) and [TbbGeIrH₂(PMe₃)₃] (17) and a reversible 1,2H-shift between 16 and 17 was studied. In the tin case 4 the dihydride [TbbSnIrH₂(PMe₃)₃] (18) was isolated exclusively. The PMe₃ and PEt₃ derivatives, 18 and [TbbSnIrH₂(PEt₃)₃] (19), respectively, could also be synthesized in reaction of [TbbSnH₂]- with the respective chloride [(R₃P)nIrCl] (R = Me n = 4, R = Et n = 3). Reaction of complex 19 with CO gives the substitution product [TbbSnIrH₂(CO)(PEt₃)₂] (20). Further reaction with CO results in hydrogen transfer from the iridium to the tin atom to give [TbbSnH₂Ir(CO)₂(PEt₃)₂] (21). The reversibility of this ligand induced reductive elimination transferring 20 to 21 is shown.