Klaus Eichele Publication Abstracts 2021

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[UP]	M. Löber, M. Ströbele, K. Eichele, C. P. Romao, H.-J. Meyer: The Lithium Iodostannate LiSn3I7: Synthesis, Properties and its Relationship to SnI2 Eur. J. Inorg. Chem. 2021(47), 4929-4934. DOI: 10.1002/ejic.202100771

The semiconducting material LiSn₃I₇ is formed in a straightforward reaction between LiI and SnI₂. Lithium ions in the structure share an octahedral site with a tin atom in (LiSn)Sn₂I₇. Its crystal structure is closely related to that of SnI₂. Solid-state NMR studies provided further insight into the structural arrangement of the compound and the differences from the structure of SnI₂.

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[UP]	M. Wiedemair, H. Kopacka, K. Wurst, T. Müller, K. Eichele, S. Vanicek, S. Hohloch, B. Bildstein: Rhodocenium Functionalization Enabled by Half-Sandwich Capping, Zincke Reaction, Diazoniation and Sandmeyer Chemistry Eur. J. Inorg. Chem. 2021(32), 3305-3313. DOI: 10.1002/ejic.202100525

In continuation of our exploration of metallocenium chemistry we report here on innovative ways toward monofunctionalized rhodocenium salts applying half-sandwich capping reactions of cyclopentadienyl rhodium(III) halide synthons with cyclopentadienyl ylides containing pyridine, phosphine or dinitrogen leaving groups, followed by Zincke and Sandmeyer reactions. Thereby amino, diazonio, bromo, azido and iodo rhodocenium salts containing valuable functional groups are accessible for the first time. Target compounds were characterized by spectroscopic (¹H/¹³C/¹⁰³Rh-NMR, IR, HR-MS), structural (single crystal XRD) and electrochemical (CV) methods and their properties were compared to those of isoelectronic cobaltocenium compounds. These new functionalized rhodocenium complexes significantly expand the so far extremely limited chemical space of rhodocenium salts with promising options for the future development in the area of rhodocenium chemistry.

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[UP]	M. Widemann, K. Eichele, H. Schubert, C. P. Sindlinger, S. Klenner, R. Pöttgen, L. Wesemann: Synthesis and Hydrogenation of Heavy Homologues of Rhodium Carbynes: [(Me3P)2(Ph3P)RhE-Ar*] (E=Sn, Pb) Angew. Chem. Int. Ed. 2021, 60(11), 5882-5889. DOI: 10.1002/anie.202015725

Tetrylidynes [(Me3P)2(Ph3P)RhSnAr*] (10) and [(Me3P)2(Ph3P)RhPbAr*] (11) are accessed for the first time via dehydrogenation of dihydrides [(Ph3P)2RhH2SnAr*] (3) and [(Ph3P)2RhH2PbAr*] (7) (Ar*=2,6-Trip2C6H3, Trip=2,4,6-triisopropylphenyl), respectively. Tin dihydride 3 was either synthesized in reaction of the dihydridostannate [Ar*SnH2]- with [(Ph3P)3RhCl] or via reaction between hydrides [(Ph3P)3RhH] and [(Ar*SnH)2]. Homologous lead hydride [(Ph3P)2RhH2PbAr*] (7) was synthesized analogously from [(Ph3P)3RhH] and [(Ar*PbH)2]. Abstraction of hydrogen from 3 and 7 supported by styrene and trimethylphosphine addition yields tetrylidynes 10 and 11. Stannylidyne 10 was also characterized by 119Sn Mössbauer spectroscopy. Hydrogenation of the triple bonds at room temperature with excess H2 gives the cis-dihydride [(Me3P)2(Ph3P)RhH2PbAr*] (12) and the tetrahydride [(Me3P)2(Ph3P)RhH2SnH2Ar*] (14). Complex 14 eliminates spontaneously one equivalent of hydrogen at room temperature to give the dihydride [(Me3P)2(Ph3P)RhH2SnAr*] (13). Hydrogen addition and elimination at stannylene tin between complexes 13 and 14 is a reversible reaction at room temperature.

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[UP]	J.-J. Maudrich, F. Diab, S. Weiß, M. Zweigart, K. Eichele, H. Schubert, R. Müller, M. Kaupp, L. Wesemann: Tetryl-Tetrylene Addition to Phenylacetylene Chem. Eur. J. 2021, 27(14), 4691-4699. DOI: 10.1002/chem.202005119

Phenylacetylene adds [Ar*GeH2-SnAr'], [Ar*GeH2-PbAr'] and [Ar'SnH2-PbAr*] at rt in a regioselective and stereoselective reaction. The highest reactivity was found for the stannylene, which reacts immediately upon addition of one equivalent of alkyne. However, the plumbylenes exhibit addition to the alkyne only in reaction with an excess of phenylacetylene. The product of the germylplumbylene addition reacts with a second equivalent of alkyne and the product of a CH-activation, a dimeric lead acetylide, were isolated. In the case of the stannylplumbylene the trans-addition product was characterized as the kinetically controlled product which isomerizes at rt to yield the cis-addition product, which is stabilized by an intramolecular Sn-H-Pb interaction. NMR chemical shifts of the olefins were investigated using two- and four-component relativistic DFT calculations, as spin-orbit effects can be large. Hydride abstraction was carried out by treating [Ar'SnPhC=CHGeH2Ar*] with the trityl salt [Ph3C][Al(OC{CF3})4] to yield a four membered ring cation.

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[UP]	D. Raiser, K. Eichele, H. Schubert, L. Wesemann: Phosphine-Stabilized Pnictinidenes Chem. Eur. J. 2021, 27(56), 14073-14080. DOI: 10.1002/chem.202102320

The reaction of the intramolecular germylene-phosphine Lewis pair (o-PPh₂)C₆H₄GeAr* (1) with Group 15 element trichlorides ECl₃ (E=P, As, Sb) was investigated. After oxidative addition, the resulting compounds (o-PPh₂)C₆H₄(Ar*)Ge(Cl)ECl₂ (2: E=P, 3: E=As, 4: E=Sb) were reduced by using sodium metal or LiHBEt₃. The molecular structures of the phosphine-stabilized phosphinidene (o-PPh₂)C₆H₄(Ar*)Ge(Cl)P (5), arsinidene (o-PPh₂)C₆H₄(Ar*)Ge(Cl)As (6) and stibinidene (o-PPh₂)C₆H₄(Ar*)Ge(Cl)Sb (7) are presented; they feature a two-coordinate low-valent Group 15 element. After chloride abstraction, a cyclic germaphosphene [(o-PPh₂)C₆H₄(Ar*)GeP] [B(C₆H₃(CF₃)₂)₄] (8) was isolated. The ³¹P NMR data of the germaphosphene were compared with literature examples and analyzed by quantum chemical calculations. The phosphinidene was treated with [iBu₂AlH]₂, and the product of an Al-H addition to the low-valent phosphorus atom (o-PPh₂)C₆H₄(Ar*)Ge(H)P(H)Al (C₄H₉)₂ (9) was characterized.

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[UP]	S. Weiß, M. Widemann, K. Eichele, H. Schubert, L. Wesemann: Low valent lead and tin hydrides in reactions with heteroallenes Dalton Trans. 2021, 50, 4952-4958. DOI: 10.1039/D1DT00542A

Low valent organoelement hydrides of tin and lead, [(Ar*SnH)2] and [(Ar*PbH)2], were reacted with diorganocarbodiimide and adamantylisocyanate to give products of hydroelementation reactions. Carbon dioxide also reacts with both low valent hydrides, but a reaction product was only characterized in the tin hydride case. A hydride was transferred to the carbon atom and the formed formate anion [HCO2]- shows coordination at two tin atoms. Carbon disulfide reacts with the stannyl-stannylene isomer of the low valent organotin hydride. The stannyl part forms a Sn-C bond whereas the stannylene moiety coordinates at the two sulfur atoms. The dimeric organolead hydride exhibits transfer of both hydride ligands to the carbon atom of CS2 to give a dithiol ligand [CH2S2]2- bridging both organolead units.