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We report infrared absorption spectra of several free radicals produced upon reaction of Cl atoms with unsaturated hydrocarbons isolated in solid $p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$. Cl atoms were produced by in situ photodissociation of Cl$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ isolated in solid $p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ at 365 nm. In experiments with the Cl$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$/C$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$/$p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ matrices, intense absorption features at 617.0, 719.8, 956.0, and 1430.5 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ and weaker ones at 577.1, 833.6, 876.8, 833.6, 983.0, 993.5, 1008.0, 1026.4, 1112.5, 1118.5, 1179.0, 1406.5, 1509.4, 2967.2, 3054.3, 3063.4, 3070.9, and 3083.9 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ appeared upon irradiation of the matrix at 365 nm and increased in intensity upon subsequent annealing of the matrix at 4.8 K for a few minutes. By comparison of vibrational wavenumbers and deuterium isotopic shifts predicted with the B3PW91 and MPW1PW91/aug-cc-pVTZ methods, these features are readily assigned to the $\sigma$-complex of ClC$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$ (chlorocyclohexadienyl radical), rather than the previously proposed $\pi$-complex. In experiments with the Cl$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$/C$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$/$p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ matrices, the 1-chloroethyl radicals (CHClCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$) and chloroethene (C$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$Cl) are identified as the main products of the Cl + C$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ reaction in solid $p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$. The assignments of IR absorption lines at 738.2, 1027.6, 1283.4, 1377.1, 1426.6, 1442.6, and 2861.2 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ to 1-chloroethyl radicals are based on comparison of the observed vibrational wavenumbers and $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$C- and D-isotopic shifts with those predicted with the B3LYP and MP2/aug-cc-pVDZ methods. These results indicate that the primary products of the addition reaction Cl + C$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$, the 2-chlorovinyl radicals, are unstable; they react readily with $p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ to form CHClCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ and C$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$Cl. If time permits, other examples such as Cl + 1, 3-butadien and H + C$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$ or C$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$H$\mathrm{<mrow\; data-mjx-texclass="ORD">5</mrow>}$Cl will be discussed. These results serve as excellent examples to demonstrate that the diminished cage effect of solid $p$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ makes production of free radicals via bimolecular reactions feasible.