  The $\Lambda_c(2590) \Sigma_c$ system can exchange a pion near the
mass-shell. Owing to the opposite intrinsic parity of the $\Lambda_c(2590)$ and
$\Sigma_c$, the pion is exchanged in S-wave. This gives rise to a Coulomb-like
force that might be able to bind the system. If one takes into account that the
pion is not exactly on the mass shell, there is a shallow S-wave state, which
we generically call the $Y_{cc}(5045)$ and $Y_{c\bar c}(5045)$ for the
$\Lambda_c(2590) \Sigma_c$ and $\Lambda_c(2590) \bar{\Sigma}_c$ systems
respectively. For the baryon-antibaryon case this Coulomb-like force is
independent of spin: the $Y_{c\bar c}(5045)$ baryonia will appear either in the
spin $S=0$ or $S=1$ configurations with G-parities $G=(-1)^{L+S+1}$. For the
baryon-baryon case the Coulomb-like force is attractive in the spin $S=0$
configuration, for which a doubly charmed molecule is expected to form near the
threshold. This type of spectrum might be very well realized in other molecular
states composed of two opposite parity hadrons with the same spin and a mass
difference close to that of a pseudo-Goldstone boson, of which a few examples
include the $\Lambda(1405) N$, $\Lambda(1520) \Sigma^*$, $\Xi(1690) \Sigma$,
$D_{s0}^*(2317) D$ and $D_{s1}^*(2460) D^*$ molecules.
