\[1\frac{1}{3}m^{5}n \cdot \left( - 1\frac{1}{2}m^{2}n \right)^{4} =\]
\[= \frac{4}{3}m^{5}n \cdot \frac{81}{16}m^{8}n^{4} =\]
\[= \frac{27}{4}m^{13}n^{5} = 6,75m^{13}n^{5}.\]