To access the hitherto almost unknown class of clustered transition metal carbonyl cations, the trimetal dodecacarbonyls M3(CO)12 (M = Ru, Os) were reacted with the oxidant Ag+[WCA]−, but yielded the silver complexes [Ag{M3(CO)12}2]+[WCA]−...

The reaction of AgBF4 and [Rh(COD)Cl]2 (COD=1,5‐cyclooctadiene) in presence of [NEt4][C5(CF3)5] afforded the fluorocarbon soluble complex [Rh(COD)(C5(CF3)5)] by salt metathesis. This complex represents the first example for a successful coordination of the weakly basic [C5(CF3)5]− ligand, since its first synthesis in 1980. In addition to [Rh(COD)(C5(CF3)5)] also the byproduct [Rh(COD)(C5(CF3)4H)] was isolated and fully characterized. Accompanying DFT studies showed that the interaction energy of the [C5(CF3)5]− ligand towards the 12‐electron fragment [Rh(COD)]+ is ≈70 kcal mol−1 lower in comparison to [C5(CH3)5]− due to reduced electrostatic interactions and weaker π‐donor properties of the ligand. The quantitative but reversible substitution of the [C5(CF3)5]− ligand by toluene, converting it into a weakly coordinating anion, experimentally proved the extraordinary weak bonding interaction.

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The oxidation power of the cyanocarbon TCNQ (tetracyano-quinodimethane) can be significantly increased to approximately E = +0.9 V vs. Cp2Fe by coordination of up to four equivalents of the strong...

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Die Reaktion zwischen AgBF 4 und [Rh-(COD)Cl] 2 (COD = 1,5-Cyclooctadien) in Gegenwart von [NEt 4 ][C 5 (CF 3 ) 5 ] ergab den perfluorcarbonlöslichen Komplex [Rh(COD)(C 5 (CF 3 ) 5 )] durch Salzmetathese. Dieser Komplex stellt das erste Beispiel für eine erfolgreiche Koordination des schwach basischen [C 5 (CF 3 ) 5 ] À -Liganden, seit dessen Erstsynthese im Jahr 1980 dar. Zusätzlich zu [Rh(COD)(C 5 (CF 3 ) 5 )] wurde das Nebenprodukt [Rh(COD)(C 5 (CF 3 ) 4 H)] isoliert und vollständig charakterisiert. Begleitende DFT-Rechnungen zeigen, dass die Interaktionsenergie des [C 5 (CF 3 ) 5 ] À -Liganden gegenüber dem 12-Elektronen [Rh(COD)] + -Fragment aufgrund verringerter elektrostatischer Interaktionen und einer schwächeren π-Donorfähigkeit um � 70 kcal mol À 1 im Vergleich zu [C 5 (CH 3 ) 5 ] À erniedrigt ist. Die quantitative, jedoch reversible Substitution des [C 5 (CF 3 ) 5 ] À -Liganden durch Toluol, die ihn in ein schwach koordinierendes Anion überführt, demonstriert experimentell die außergewöhnlich schwache Bindungssituation.

The oxidation power of the cyanocarbon TCNQ (tetracyano-quinodimethane) can be significantly increased to approximately E = +0.9 V vs. Cp2Fe by coordination of up to four equivalents of the strong fluorinated Lewis acid B(C6F5)3. Thianthrene and tris(4-bromophenyl)amine were oxidized to the corresponding radical cations. Dianionic [TCNQ∙4 B(C6F5)3]2ꟷ was formed upon reduction with two equivalents of ferrocene or decamethylcobaltocene.

Octacyanometalates K4[Mo(CN)8] and K4[W(CN)8] are completely protonated in superacidic mixtures of anhydrous hydrogen fluoride and antimony pentafluoride. The resulting hydrogen isocyanide complexes [Mo(CNH)8]4+ [SbF6]−4 and [W(CNH)8]4+ [SbF6]−4 are the first examples of eight‐coordinate homoleptic metal complexes containing hydrogen isocyanide (CNH) ligands. The complexes were crystallographically characterized, revealing hydrogen‐bonded networks with short N⋅⋅⋅H⋅⋅⋅F contacts. Low‐temperature NMR measurements in HF confirmed rapid proton exchange even at −40 °C. Upon protonation, ν(C≡N) increases of about 50 cm−1 which is in agreement with DFT calculations.