  The role of weakly bound neutral clusters, such as dineutrons and
tetraneutrons, in matter of high density and high temperature is discussed.
Under such conditions, which are characteristic of core-collapse supernovae,
the lifetime of multineutrons may prove to be sufficiently long for them to
have a pronounced effect on the formation of the chemical composition. The
influence of the multineutron binding energy and other nuclear properties on
the magnitude of the effect being considered is examined.
