**Antonio Bauzá \* and Antonio Frontera \***

Department of Chemistry, Universitat de les Illes Balears, Crta de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain **\*** Correspondence: antonio.bauza@uib.es (A.B.); toni.frontera@uib.es (A.F.); Fax.: +34-971-173426 (A.F.)

Academic Editor: Steve Scheiner Received: 3 July 2018; Accepted: 15 July 2018; Published: 19 July 2018

**Abstract:** In this manuscript, we combined DFT calculations (PBE0-D3/def2-TZVP level of theory) and a Cambridge Structural Database (CSD) survey to evaluate the ability of perchlorinated cyclopenta- and cyclohexatetrelanes in establishing tetrel bonding interactions. For this purpose, we used Tr5Cl10 and Tr6Cl12 (Tr = Si and Ge) and HCN, HF, OH− and Cl− as electron donor entities. Furthermore, we performed an Atoms in Molecules (AIM) analysis to further describe and characterize the interactions studied herein. A survey of crystal structures in the CSD reveals that close contacts between Si and lone-pair-possessing atoms are quite common and oriented along the extension of the covalent bond formed by the silicon with the halogen atom.

**Keywords:** tetrel bonding interactions; CSD search; DFT calculations; AIM analysis
