Klaus Eichele

Although transition metal tetrylidynes have been known for several decades, analogous heavy ditetrylidynes have not been reported in the literature to this day. In this work we describe the synthesis and characterization of iridium distannylidyne [(Me ₃ P) ₂ Ir(SnAr*) ₂ ][WCA] ( 1a / 1b ) {[WCA] = [Al(O ^t Bu ^F ) ₄ ] ^– ( 1a ), [BAr ^F ₄ ] ^– ( 1b ); Ar* = 2,6‐bis(2,4,6‐tri‐ iso ‐propylphenyl)phenyl, ^t Bu ^F = C(CF ₃ ) ₃ , Ar ^F = 3,5‐bis(trifluoromethyl)phenyl} as the first transition metal ditetrylidyne. 1 reacts with two equivalents of CO ₂ to give [(Me ₃ P) ₂ Ir(SnAr*) ₂ ( μ ₃ ‐ η ³ ‐ κ ³ ‐ O , C , O’ ‐CO ₂ ) ₂ ][Al(O ^t Bu ^F ) ₄ ] ( 2 ). In the presence of excess trimethylphosphine, trimethylsilyl azide reacts with 1 to form imido‐bridged [(Me ₃ P) ₃ Ir(SnAr*) ₂ ( μ ₂ ‐N–TMS)][BAr ^F ₄ ] ( 3 ) upon extrusion of N ₂ .

Although transition metal tetrylidynes have been known for several decades, analogous heavy ditetrylidynes have not been reported in the literature to this day. In this work we describe the synthesis and characterization of iridium distannylidyne [(Me ₃ P) ₂ Ir(SnAr*) ₂ ][WCA] ( 1a / 1b ) {[WCA] = [Al(O ^t Bu ^F ) ₄ ] ^– ( 1a ), [BAr ^F ₄ ] ^– ( 1b ); Ar* = 2,6‐bis(2,4,6‐tri‐ iso ‐propylphenyl)phenyl, ^t Bu ^F = C(CF ₃ ) ₃ , Ar ^F = 3,5‐bis(trifluoromethyl)phenyl} as the first transition metal ditetrylidyne. 1 reacts with two equivalents of CO ₂ to give [(Me ₃ P) ₂ Ir(SnAr*) ₂ ( μ ₃ ‐ η ³ ‐ κ ³ ‐ O , C , O’ ‐CO ₂ ) ₂ ][Al(O ^t Bu ^F ) ₄ ] ( 2 ). In the presence of excess trimethylphosphine, trimethylsilyl azide reacts with 1 to form imido‐bridged [(Me ₃ P) ₃ Ir(SnAr*) ₂ ( μ ₂ ‐N–TMS)][BAr ^F ₄ ] ( 3 ) upon extrusion of N ₂ .

A comparative reactivity study of Group 9 tetrylidines [(Me ₃ P) ₃ MEAr*] [M = Rh, E = Ge (1), Sn (2); M = Ir, E = Ge (3), Sn (4)] is presented.

Stibagermene and stibadigermaallyl were synthesized following oxidative SbCl ₃ addition to a cyclic digermene, reduction with [( ^Mes Nacnac)Mg] ₂ , and chloride abstraction.

Terphenylgermanium Ar*Ge [Ar*=C₆H₃(2,6‐Trip)₂, Trip=2,4,6‐C₆H₂iPr₃] was found to act as a novel μ₂‐Ge‐bis(hexahapto‐Trip) bridging ligand. Deprotonated terphenyl germanium trihydride [Li(thf)₃][Ar*GeH₂] (1) undergoes reductive elimination and transfer of hydrogen in reaction with dimeric [(COD)RhCl]₂ to yield the dinuclear complex [Ar*GeRh(COE)RhCl(COD)] (2). Subsequent chloride abstraction from compound 2 using Na[BAr^F₄] or Li[Al(O^tBu^F)₄] results in the cationic complexes [Ar*GeRh(COE)Rh(COD)][WCA] (3) {WCA: [BAr^F₄]⁻ (Ar^F=C₆H₃–3,5‐(CF₃)₂), [Al(O^tBu^F)₄]⁻}. Ligand exchange of olefin for CO yields the carbonyl complex [Ar*Ge(Rh(CO))₂][BAr^F₄] (4). In an alternative approach to the synthesis of carbonyl complex 4, [Li(thf)₃][Ar*GeH₂] (1) was treated with [Rh(CO)₂Cl]₂ leading to the isolation of a hexanuclear rhodium cluster [(μ₃‐Ar*Ge)₂{Rh(CO)₂}₆(μ₃‐H)₂] (5) in reasonable yield. In reactions with [Rh(CO)₂Cl]₂ or [Ph₃PAuCl] complex 4 abstracts the chloride ligand and forms tetranuclear complexes featuring a GeRh₃‐ or GeRh₂Au‐rectangle, [Ar*GeCl(Rh₃(CO)₄)][BAr^F₄] (6), or [Ar*GeCl{Rh₂(CO)₂}(AuPPh₃)][BAr^F₄] (7).

Group 3 and 13 light metal pyrazolates reversibly insert carbon dioxide. The inverse correlation of their catalytic activity and carboxophilicity is striking.

The tetracyanamidometallates Li₄[T(CN₂)₄] with T=Si, Ge were prepared by solid‐state metathesis (SSM) reactions between TI₄ and Li₂(CN₂). The new compounds Li₄[T(CN₂)₄] are obtained as crystalline phases in high yields and represent the most basic examples of the family of tetracyanamidometallates. The formation of these compounds, via SiI₄ and Li₂(CN₂), is analyzed by means of differential scanning calorimetry (DSC). The [Si(CN₂)₄]⁴⁻ ion in the structure of Li₄[Si(CN₂)₄] can be considered an analogue to the [SiO₄]⁴⁻ ion in Li₄SiO₄. The crystal structures of Li₄[T(CN₂)₄] were solved and refined isotypically on the basis of single‐crystal X‐ray diffraction data in the space group C2/c, and further characterized by infrared and solid‐state NMR techniques.

The mixed lithium tin iodide LiSn₃I₇ was prepared by reacting LiI and SnI₂ at 300 °C. Single‐crystal X‐ray diffraction revealed a crystal structure related to that of SnI₂, with nearly identical coordination environments of tin atoms. The lithium ion in the structure of LiSn₃I₇ shares one crystallographic position with a tin atom in octahedral voids of (LiSn)Sn₂I₇, as confirmed by solid‐state ⁷Li, ¹¹⁹Sn and ¹²⁷I MAS NMR spectra. DFT band structure calculations show LiSn₃I₇ to be a semiconductor with an indirect bandgap on the order of 2 eV.

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.