  We study two Weyl semimetal generalizations in five dimensions (5d) which
have Yang monopoles and linked Weyl surfaces in the Brillouin zone,
respectively, and carry the second Chern number as a topological number. In
particular, we show a Yang monopole naturally reduces to a Hopf link of two
Weyl surfaces when the $\mathbf{TP}$ (time-reversal combined with
space-inversion) symmetry is broken. We then examine the phase transition
between insulators with different topological numbers in 5d. In analogy to the
3d case, 5d Weyl semimetals emerge as intermediate phases during the
topological phase transition.
