$\left(\mathrm{CH}_3\right)_4 \mathrm{Sn}$ is an organometallic compound where tin is bonded to four methyl groups via single σ-bonds. It does not involve $\pi$-bonding. The other compounds listed involve π-interactions with ligands like ethylene ($\eta^2$), cyclopentadienyl ($\eta^5$), and benzene (\eta^6).