# Is it true if $[LL] = L$ then $L$ is a semisimple Lie algebra?

Let $L$ be a finite dimensional Lie algebra over $\mathbb{C}$. It is classical theorem that if $L$ is semisimple, then $[LL] = L$.

Is it true if $[LL] = L$ then $L$ is a semisimple Lie algebra? I've been looking for counterexamples, but didn't find one yet.

One counterexample is the semidirect product $\mathfrak{sl}_n(\mathbb{C}) \ltimes \mathbb{C}^n$, where $\mathfrak{sl}_n(\mathbb{C})$ acts naturally on $\mathbb{C}^n$.