Spin crossover complexes with ligands suitable for further functionalization could allow for an easy access to multifunctional switchable materials. Within this context, we recently characterized the Fe(II) SCO complexes of propargyl-1H-tetrazole. Although the design of the ligand seems similar to the one of the well-known propyl-1H-tetrazole, the spin transition behavior is notably different. Both compounds reported herein feature a gradual spin transition with a T 1/2 shifted to lower

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... ures, compared to the more flexible propyl-ligand. Due to the potential instable structure of these compounds, especially of the perchlorate complex, we also investigated our compounds with regard to their sensitivity against thermal and mechanical stress. These experiments led to the conclusion that the proper handling includes no enhanced risk of explosive decomposition. Magnetochemistry 2016, 2, 12 2 of 13 of SCO compounds. In combination, these two examples are illustrative for the always mentioned potential applicability of SCO materials. To keep up with today's technological demands, combinations of the SCO effect with additional properties would be appealing. Therefore, a recent trend is the introduction of multifunctionality to SCO in the form of, e.g. ligand isomerism [6], luminescence [19, 20] , nonlinear optics [21], or host-guest chemistry [22] [23] [24] , thus allowing for a broader scope of possible applications. One concept for the introduction of multifunctionality that our group recently started to investigate is the post-functionalization of suitable SCO complexes. This approach is based on the strategy of avoiding time-consuming ligand design by having one suitable "platform", allowing for quick and easy further functionalization according to the respective demands. In this context, the use of a ligand with a carbon-carbon triple bond was considered a proper structural motif. Herein, we report the synthesis and characterization of two Fe(II) SCO complexes based on the propargyl-1H-tetrazole ligand (prgTz). project P24955-N28. The computational results presented have been achieved using the Vienna Scientific Cluster. Thanks are also due to the X-ray center of Vienna University of Technology (Klaudia Hradil).