  Most of the work involving entanglement measurement focuses on systems that
can be modeled by two interacting qubits. This is due to the fact that there
are few studies presenting entanglement analytical calculations in systems with
spins $s > 1/2$. In this paper we present for the first time an analytical way
of calculating thermal entanglement in a dimension $2\otimes3$ Heisenberg chain
through the distance between states. We use the Hilbert-Schmidt norm to obtain
entanglement. The result obtained can be used to calculate entanglement in
chains with spin-$1/2$ coupling with spin-$1$, such as ferrimagnetic compounds
as well as compounds with dimer-trimer coupling.
