Intermetallic borides are characterized by a great variety of crystal structures and bonding interactions, however, a comprehensive rationalisation of the electronic structure is missing. A more general interpretation will be targeted towards comparing several boride phases of one particular transition metal on one hand side, but also isostructural borides of various metals at the other side. Finally, a concise model should result from a detailed analysis of excellent data both from experimental charge density analysis and quantum chemical methods. Ultimate target is a transferability model based on typical building blocks. Experimental investigations of the electron density derived from diffraction data are very rare for intermetallic compounds. One of the main reasons is that the suitability of such compounds for charge density analysis is estimated to be relatively low as compared to organic compounds. In the present work, X-ray single crystal diffraction measurements up to high resolution were carried out for TiB2, VB2, V3B4, and VB crystals. The respective experimental electron densities were reconstructed using the multipole model introduced by Hansen and Coppens [1]. The topological aspects of the experimental electron density were analysed on the basis of the multipole parameters using Bader’s Quantum Theory, Atoms in Molecules [2] and compared with theoretical calculations. References [1] Hansen, N.K.; Coppens, P. Acta Crystallogr. 1978, A34, 909 [2] Bader, R.F.W. Atoms in Molecules─A Quantum Theory; Oxford University Press: Oxford, 1990

Intermetallic borides are characterized by a great variety of crystal structures and bonding interactions, however, a comprehensive rationalisation of the electronic structure is missing. A more general interpretation will be targeted towards comparing several boride phases of one particular transition metal on one hand side, but also isostructural borides of various metals at the other side. Finally, a concise model should result from a detailed analysis of excellent data both from experimental charge density analysis and quantum chemical methods. Ultimate target is a transferability model based on typical building blocks. Experimental investigations of the electron density derived from diffraction data are very rare for intermetallic compounds. One of the main reasons is that the suitability of such compounds for charge density analysis is estimated to be relatively low as compared to organic compounds. In the present work, X-ray single crystal diffraction measurements up to high resolution were carried out for TiB2, VB2, V3B4, and VB crystals. The respective experimental electron densities were reconstructed using the multipole model introduced by Hansen and Coppens [1]. The topological aspects of the experimental electron density were analysed on the basis of the multipole parameters using Bader’s Quantum Theory, Atoms in Molecules [2] and compared with theoretical calculations. References [1] Hansen, N.K.; Coppens, P. Acta Crystallogr. 1978, A34, 909 [2] Bader, R.F.W. Atoms in Molecules─A Quantum Theory; Oxford University Press: Oxford, 1990