Photoelectron spectroscopy and theoretical calculations have identified the global minimum structure of the 16-valence electron Si3Cu3 - cluster, which features a planar tetracoordinate silicon (ptSi) in a rhombic arrangement. The Si3 and Cu3 triangles are interconnected by a Si2/Cu2 edge, forming an ordered chain-like structure. Besides the conventional 2c-2e σ-bond connecting Si3 and Cu3, the stability of this cluster is reinforced by a delocalized 3c-2e σ-bond in Cu3 and a π-bond in Si3. Our study provides experimental confirmation of a planar hypercoordinate heavier Group 14 element, opening possibilities for exploring similar structures in two-dimensional materials.
Keywords: chemical bonding; global minimum; photoelectron spectroscopy; planar tetracoordinate silicon.
© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.