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New KIT Phone numbers from January 01, 2011: Please note that our phone numbers have been extended from four to five digits.

New Collaborative Research Centre “Kooperative Effekte in homo- und heterometallischen Komplexen (3MET)”

The preparation and structures of new heteronuclear [1.1.1]propellanes E₂Si₃Mes₆ have been reported (Mes = 2,4,6-Me₃C₆H₂), together with their electronic properties, photochemically controllable radical-type reactivities, and reaction products thereof.

In recent collaborative papers with the groups of Dietmar Stalke and David Scheschkewitz we reported on experimental charge density distribution in [Mg{(pz*)₃C}₂], (pz* = 3,5-dimethylpyrazolyl), containing two non-coordinating sp3 carbanionic lone-pairs (Figure a) and the transfer of a disilenyl moiety to aromatic substrates and lateral functional group transformation in aryl disilenes (Figure b), respectively.

The icing on the cake: We have recently reported on the successful synthesis of the first pentasilapropellane, Si₅Mes₆ (Mes = 2,4,6-trimethylphenyl), which consists of an archetypal [1.1.1] cluster core featuring two ligand free, “inverted tetrahedral” bridgehead silicon atoms. The separation between the latter is much longer, and the bond strength is much weaker, than usually observed for a regular Si-Si single bond. A detailed analysis of the electronic characteristics of Si₅Mes₆ revealed a low-lying excited triplet state, indicative for some biradical(oid) character. Reactivity studies provided evidence for both closed-shell and radical type reactivity, confirming the unusual nature of the stretched silicon silicon bond in this “non-classical” molecule (this contribution has been highlighted recently)

In a recent collaborative paper with the group of Holger Braunschweig we reported on the reduction chemistry of ferrocenylborol: One electron reduction of 1-ferrocenyl-2,3,4,5-tetraphenylborole results in a radical anion with 5 electrons in the borole ring. Both EPR spectroscopic investigations and spin density calculations confirm the formation of a borol radical (see picture). Further one-electron reduction stimulates an intramolecular [(C₅H₅)Fe] migration from the cyclopentadienyl anion to the borole dianion.

Radical-Type Reactivity of Metalla[1.1.1]propellanes of Group 14: The preparation and structures of new metal-terminated bicyclo[1.1.1]pentastannanes are reported, together with preparative and electrochemical studies on their reduction chemistry.

We have recently reported on the utility of multifunctional, k¹Si:k³S-coordinated tris(methimazolyl)silanide ligands [Si(mt^Me)₃]^- for the stabilisation of a triangulo palladium cluster [Pd₃{Si(mt^Me)₃}₂] (see picture) consisting of very unusual m³-capping SiR₃ donors. Differences to the corresponding platinum chemistry were supported by NMR spectroscopy and DFT calculations. This article is part of the ‘Emerging Investigators’ themed issue for Chem. Commun.