Confined molecular chambers such as macrocycle bridged E-1-H...H-E-2 (E-1(E-2) = Si(Si), 1) exhibit rare ultrashort HH nonbonded contacts (d(H...H) = 1.56 angstrom). In this article, on the basis of density functional theory and ab initio molecular dynamics simulations, we propose new molecular motifs where d(H...H) can be reduced to 1.44 angstrom (E-1(E-2) = Si(Ge), 3). Further tuning the structure of the macrocycle by replacing the bulky phenyl groups by ethylenic spacers and substitution of the H-atoms by -CN groups makes the cavity more compact and furnishes even shorter d(HH) = 1.38 angstrom (E-1(E-2) = Ge(Ge), 8). These unusually close HH nonbonded contacts originate from the strong attractive noncovalent interactions between them, which are evident from various computational indicators, namely, NCI, Wiberg bond index, relaxed force constant, quantum theory of atoms in molecules, and natural orbitals for chemical valence combined with the extended transition state method analyses. Substantial stabilization of the in,in-configuration (exhibiting short HH contacts) compared with the out,out-configuration (by similar to 5.7 kcal/mol) and statistically insignificant fluctuations in < d(H....H)> and (theta(E-1(E-2)-H....H = 152 degrees) at room temperature confirm that the ultrashort HH distances in these molecules are thermodynamically stable and would be persistent under ambient experimental conditions.