  A Lie-admissible algebra gives by anticommutativity a Lie algebra. In this
work we study remarkable classes of Lie-admissible algebras such as Vinberg,
PreLie algebras. We compute the corresponding binary quadratic operads and
study their Koszul duality. Considering Lie algebras as Lie-admissible algebras
we can define for each Lie algebra a cohomology with values in a Lie-admissible
module. This permits to study some deformations of Lie algebras in the category
of Lie-admissible algebras. Lastly we study the tensor product between these
operads and their dual operads. As application we construct new classes of
Vinberg algebras.
