The main focus is on the struture and reactivity of group 14 elements. Using mainly DFT methods, the reactivity of silylenes and germylenes are studied and compared. While for instance, the former react with diacetylenes under formation of bissilirenes, while germylenes form a bisgermaethene with a conjugated p-system.

Further interesting compounds are the isomeric structures of Si₄R₆ and Ge₄R₆, respectively. The influence of small to very bulky substituents on the stability of these isomers is investigated, further information come from population analyses, in particular of the bridge bond of the bicyclotetrasila- and bicyclotetragermabutane.

In 2003, the first homonuclear ring system containing lead atoms has been synthesised. The substituent orientation and the proposed bonding situation motivated theoretical investigations of Sn and Pb rings. For instance, the Pb-Pb bonds in Pb₃R₆ are interactions of an occupied lead orbital and an empty p orbital of a neighbouring lead atom.

Untersuchungen an Carbeniumionen mittels ESI-Massenspektrometrie (in the group of apl. Prof. Jürgen O. Metzger)

Theoretical Group 14 chemistry. Part 3. A DFT Study of Ge₄R₆, R. Koch, T. Bruhn, M. Weidenbruch, J. Mol. Struct. (THEOCHEM) 2005, 714, 109-115 .

Iminopropadienones R-N=C=C=C=O and carbon suboxide, C₃O₂. Theoretical and experimental ¹³C NMR spectra, R. Koch, T. Bruhn, R. N. Veedu, C. Wentrup, J. Mol. Struct. (THEOCHEM) 2004, 686, 31 – 36.

Theoretical Group 14 chemistry. Part 2. Si₄R₆ – a theoretical approach, R. Koch, T. Bruhn, M. Weidenbruch, J. Mol. Struct. (THEOCHEM) 2004, 680, 91-97.

Silylene and Germylene Additions to 1,3-Diynes: Bis(silacyclopropenes) vs. Germaethenes Formation, a DFT Study, R. Koch, T. Bruhn, M. Weidenbruch, Organometallics 2004, 23, 1570-1575.

Investigation of Reactive Intermediates of Chemical Reactions in Solution by Electrospray Ionization Mass Spectrometry: Radical Chain Reactions, J. Griep-Raming, S. Meyer, T. Bruhn, J. O. Metzger, Angew. Chem. 2002, 114, 2863 - 2866; Angew. Chem. Int. Ed. 2002, 41, 2738 - 2742.

Synthesis and recognition behaviour of allosteric hemicarcerands, A. Lützen, O. Haß, T. Bruhn, Tetrahedron Letters 2002, 43, 1807 - 1811.

Quantummechanical study of homonuclear lead rings, R. Koch, T. Bruhn, M. Weidenbruch, Poster, Tag der Chemie, Universität Oldenburg, 29.01.2004.

The Addition of Silylenes and Germylens to Diacetylenes - A DFT Study, R. Koch, T. Bruhn, M. Weidenbruch, Poster, presented by R. Koch, 39th IUPAC Congress, Ottawa, Canada, 10. - 15.08.2003.

The Addition of Silylenes and Germylens to Diacetylenes - A DFT Study, R. Koch, T. Bruhn, M. Weidenbruch, Poster, 17. Darmstädter Molecular Modelling Workshop, Computer-Chemie-Centrum Erlangen, 27. - 28.05.2003.

The Addition of Silylenes and Germylens to Diacetylenes - A DFT Study, R. Koch, T. Bruhn, M. Weidenbruch, Poster, Tag der Chemie, Universität Oldenburg, 06.02.2003.

Algorithms for the Recognition and Suppression of Spikes and Electronic Noise in Mass Spectral Data, J. Griep-Raming, T. Bruhn, J. O. Metzger, Poster, presented by J. Griep Raming, 50th ASMS Conference, Orlando, FL, USA, 02.06 - 06.06. 2002.

Untersuchung der Dissoziation von Kohlenstoff-Heteroatom-Bindungen in Lösung: Nachweis der Carbokationen und der Anionen durch ESI-MS, T. Bruhn, J. O. Metzger, Poster, Diskussionstagung der DGMS in Heidelberg, 03.03. - 06.03. 2002.

Auf dem Weg zum direkten Nachweis von Carbeniumionen in Lösung, T. Bruhn, J. O. Metzger, Poster, Tag der Chemie, Universität Oldenburg, 08.11.2001.