From μ3- to μ- agostic methyl coordination: NMR and solid state study of donor ligands uptake by the triangular cluster anion [Re3(μ-H)3(μ3-CH3)(CO)9]- [From mu(3)- to mu- agostic methyl coordination: NMR and solid state study of donor ligands uptake by the triangular cluster anion [Re-3(mu-H)(3)(mu(3)-CH3) (CO)(9)](-)]