Our principal research interests are summarised here.

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A detailed listing of our publications can be found in this section.

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Current and former group members, also including some group pictures.

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Online documents and links to teaching materials.

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Our main research facilities are summarised in this subitem.

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Recent News

Great group excursion in July 2017: biking, rafting, riding carousels, enjoying the time!

A dinuclear [FeRh] complex containing a redox-active [1]phosphaferrocenophane metalloligand was employed as redox-switchable rhodium catalyst in the hydrosilylation of terminal alkynes. As evidenced by activity and selectivity differences, distinct mechanisms are operating for the neutral and the cationic complex, namely the alternative Chalk–Harrod mechanism for [FeRh] and the classical variant for [FeRh]+. An “oxidatively induced reductive elimination” step was identified as the origin of the observed cooperative effect. The results were recently published as a Frontispiece-featured Communication in Chem. Eur. J. (click here).

Multidentate Silyl Ligands: A recent review summarises the use of multidentate Si-based ligand systems in transition metal coordination chemistry. These include tri- and tetradentate pincer and scorpionate-type ligands, which have been developed in recent years in order to tailor both steric and electronic properties for achieving a defined control over the reactivity of a transition metal complex. A discussion of synthetic and structural aspects of several subgroups of ligand architectures is presented (click here).

Redox-switchable catalysis: Palladium(II) complexes of two differently substituted [1]phosphaferrocenophanes FcPR (R = Mes, biaryl) and of diphenylferrocenyl phosphine Ph2PFc were applied in redox-switchable Buchwald-Hartwig cross-coupling reactions. The results were recently published as part of the themed collection „Switchable Catalysis and Related Reactions“ in Inorg. Chem. Front. (click here).

The redox-switchable germylene [Fc(NMes)2Ge] based on a [3]ferrocenophane ligand arrangement, alongside some transition metal complexes, are reported. The change in the ligating properties upon oxidation were elucidated by DFT calculations on neutral and cationic bimetallic model complexes. The results were recently published in Chem. Eur. J. (click here).

Congratulations to Michael and Wolfram for their Procter & Gamble awards for the best MA-theses in 2015/2016! The picture taken at the ceremony on November 10 shows the recipients alongside the P&G representative and the MA-theses supervisors.

Great group excursion to the Black Forest in July 2016: „Flussbettwanderung im Murgtal“… somewhat slippery when wet 😉

Our collaborative study with the group of Rodrigue Lescouëzec (see below) was recently featured on the front-cover of issue 8 (see also here).

Collaborative study within a Co-tutelle framework between the KIT and Sorbonne Universités, UPMC (Prof. Lescouëzec): A straightforward access to a new cyanide-bridged {Fe4Co4} “molecular box” containing a potassium ion, namely  K@{[FeII(Tp)(CN)3]4[CoIII(pzTp)]3[CoII(pzTp)]} (1) (with Tp and pzTp = tris- and tetrakis(pyrazolyl)borate, respectively), is provided alongside its full characterisation. A detailed analysis of the molecular structure (X-ray diffraction, mass spectrometry, NMR spectroscopy) and electronic properties (EPR spectroscopy, SQUID magnetometry, UV/Vis spectroscopy, cyclic voltammetry) reveals that 1 shows slow magnetic relaxation and a remarkable photomagnetic effect at low temperature, which is reminiscent to some FeCo Prussian Blue Analogues (PBAs) and ascribed to a photo-induced electron transfer. However, in contrast with these inorganic polymers, the overall neutral compound 1 is soluble and remarkably stable in organic solvents such as CH2Cl2. Moreover, 1 shows an interesting redox versatility, electrochemical experiments revealing the possible access to six stable redox states. The results were recently published in Chem. Sci. (click here).

Hidden FLPs: Two aluminium diphosphamethanide complexes are reported featuring four-membered PCPAl core structures and diphosphaallyl ligands. The aluminium complex [Al(tBu)2{Mes*PCHPMes*}] reacts with molecular dihydrogen at room temperature under formation of the acyclic diphosphine Mes*PCHP(H)Mes* (PH) and the corresponding dialkyl aluminium hydride [tBu2AlH]3 (AlH, see Figure). The results were recently published as Communication in Chem. Eur. J. (click here).

Fluorinated at boron: The mono- and dinuclear copper complexes [CuII(FTp*)2] and [CuI2(FTp*)2] containing the so-far unprecedented boron-fluorinated FTp* ligand are reported. The short CuCu distance in [CuI2(FTp*)2] was predicted by DFT-D3 calculations to be dictated by dispersion interactions between all atoms in the complex while the Cu-Cu dispersion contribution itself is only very small. The results were recently published in Chem. Eur. J. (click here).

Collaborative study with Gerald Hörner (TU Berlin): We have provided a straightforward access is provided to iron(II) complexes showing exceedingly slow spin-state interconversion by utilizing trigonal-prismatic directing ligands of the extended-tripod type. A detailed analysis of the interrelations between complex structure (X-ray diffraction, density functional theory) and electronic character (SQUID magnetometry, Mössbauer spectroscopy, UV/vis spectroscopy) of the iron(II) center in mononuclear complexes [Fe(L)] reveals spin crossover to occur along a coupled breathing/torsion reaction coordinate, shuttling the complex between the octahedral low-spin state and the trigonal-prismatic high-spin state along Bailar’s trigonal twist pathway. We associate both the long spin-state lifetimes in the millisecond domain close to room temperature and the substantial barriers against thermal scrambling  with stereochemical constraints. In particular, the topology of the κ6N ligands controls the temporary and structural dynamics during spin crossover. The results were recently published in Inorg. Chem. (click here).

Collaborative study with the group of Wim Klopper on cooperative effects (SFB 3MET): A new concept has been applied to the analysis of UV/Vis spectra of homotrinuclear transition-metal complexes by means of a many-body expansion of the change in the spectrum induced by replacing each of the three transition-metal ions in the complex by another transition-metal ion to yield a new homotrinuclear transition-metal complex. The results were recently published in Chem. Phys. Chem. (click here) and selected as VIP paper (see also here).

Two successful PhD defenses in February and April: congratulations to Alexander Feyrer and Eric Moos!!


Group excursion to the Fun Forest Kandel in August 2015.

Collaborative study with the group of Guy Bertrand: The chemical reduction of a pyridyl-substituted cyclic (alkyl)(amino)carbene (CAAC) iminium gave a highly stable organic radical. The neutral paramagnetic species was fully characterised; the unpaired electron is delocalised on both the CAAC and the pyridine heterocycles. The results were recently published in Chem. Eur. J. (click here) and selected as „Hot Paper“ (see also here).

Nice collaborative study with the group of Hansgeorg Schnöckel: since Mg+ ions are isoelectronic to Na atoms, an easy single electron transfer (SET) can be expected for MgBr. Even at 190 K, the radical MgBr (obtained via its sophisticated condensation) in a metastable solution transfers its electron to a diazadiene entity. A paramagnetic Mg(II) compound [MgBr(L1)˙]2 (L1 = DippN=C(Me)C(Me)=NDipp) is formed consisting of a singly reduced ligand. As shown by EPR investigations, the dimeric complex dissociates in ethereal solvents to two monomeric subunits. In addition, the complex can subsequently be reduced with potassium to furnish again a Mg(I) compound, namely [K(thf)3]2[Mg2(L1)2], which was reported previously. The results were recently published in Chem. Commun. (click here) and featured on the inside front cover of issue 99.

In a collaborative study, the one-electron oxidation of a series of diaryldichalcogenides was studied in the groups of Konrad Seppelt and Jens Beckmann. The electronic and structural properties of the radical cations [(2,6-Mes2C6H3E)2+ (E = S, Se, Te) were probed by Jeff Harmer and our group with the aid of EPR spectroscopy and density functional theory calculations. The paper was recently published in Chem Sci. (click here) and belongs to the Top 25 most downloaded Chemical Science articles October-December 2014 (click here).

The preparation and structures of Tpm-based heterobimetallic complexes are reported, also including the first complexes containing Zn-Cr, Cd-Cr, and Cd-Mo bonds. The nature of the metal-metal bonds was probed by quantum chemical calculations. The results were recently published in Chem. Eur. J. (click here).

In a recent collaborative paper with several groups of the SFB 3MET we reported on a detailed theoretical and spectroscopic study on the electronically excited states of a highly symmetric, trinuclear palladium complex both in the gas phase and in solution. The results were published in Phys. Chem. Chem. Phys. (click here). In a follow-up paper, different time-resolved IR spectroscopic methods covering the femtosecond up to the microsecond range as well as density functional computations have been performed to unravel the structure and character of this complex in the electronically excited state. The results were also published in Phys. Chem. Chem. Phys. (click here).

The preparation and structures of coinage metal complexes of tris(pyrazolyl)methanide-based redox-active metalloligands are reported, together with density functional theory (DFT) calculations and detailed cyclic voltammetry studies in solution in order to elucidate a conceivable electronic interplay between the metal atoms. The results were recently published in Organometallics (click here)

Recently, the 5th German edition of the renowned Inorganic Chemistry textbook “Huheey” appeared, again with contributions from our side.

Huheey, James E. / Keiter, Ellen A. / Keiter, Richard L.

Anorganische Chemie

Hrsg. v. Steudel, Ralf

Bearb. v. Breher, Frank / Finze, Maik / Johrendt, Dirk / Lunk, Hans-Joachim / Kaupp, Martin / Radius, Udo / Schatzschneider, Ulrich
DeGruyter, 2014

By using a multifunctional silyl ligand based on the tris(3,5-dimethylpyrazolyl)silyl scaffold [Si(3,5-Me2pz)3], we succeeded in obtaining the homoleptic tetrakis(silyl) complexes of Pd0 and Pt0, which were characterized by various methods, including multinuclear NMR spectroscopic techniques, cyclic voltammetry in combination with DFT calculations, X-ray crystallography, and EPR spectroscopy. The complexes form very unusual metal-centered heterocubane structures in the solid state and in solution. The rather rigid heterocubane ligand shells were found to facilitate the stepwise, quasi-reversible oxidation to their d9 MI and d8 MII analogues (click here; see also cover of issue 52 and spotlight on ChemistryViews).

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Karlsruhe Institute of Technology (KIT)
Institute of Inorganic Chemistry
Engesserstr. 15
Gebäude 30.45
76131 Karlsruhe


Prof. Dr. Frank Breher
Phone: +49-(0)721-608 448 55
Fax: +49-(0)721-608 470 21
Email: breher@kit.edu