  We compare by a very elementary approach the second adjoint and trivial
Leibniz cohomology spaces of a Lie algebra to the usual ones. Examples are
given of coupled cocycles. Some properties are deduced as to Leibniz
deformations. We also consider the class of Lie algebras for which the Koszul
3-form is zero, and prove that it contains all quotients of Borel subalgebras,
or of their nilradicals, of finite dimensional semisimple Lie algebras.
Finally, a list of Kac-Moody types for indecomposable nilpotent Lie algebras of
dimension $\leqslant 7$ is given.
