In comparison with metallabenzene and its derivatives,metallabicyclic complexes are less developed.Still,limited examples,e.g.,iridabicyclooctatriene1,osmapentalyne2 and osmapentalene3,have been synthesized.Interestingly,osmapentalyne and osmapentalene are M(o)bious aromatic system with a planar topology.Following our previous study4 on the aromaticity and stability of osmasilapentalyne,we carry out DFT calculations to examine whether the aromaticity in osmasilapentalene will be retained as osmasilapentalyne although the silicon atom is reluctant to participate in π bonding5.The computed NICS and ISE values reveal the reduced aromaticity in both 16 and 18 valence electrons osmasilapentalene.In addition,the effects of ligands and substituents on the aromaticity of osmasilapentalene are also discussed.All of these findings could be helpful for the synthesis of the first metallasilapentalene.