LAUSR

Detailed DFT calculations of the published [CpTi(μ2-Me)(μ2-NPPh3)(μ5-C)(μ2-AlMe2)2(AlMe2)(AlMe3)] 1 revealed the triple-bond nature of the Ti-C bond and thus being a methide carbon with 5 surrounding ligands. This finding was further corroborated by the derivates [CpTi(μ2-Me)(μ2-NPPh3)(μ4-C)(μ2-AlMe2)2(AlMe2)] 3, which has one AlMe3 ligand "removed" compared to 1, and [CpTi(μ2-NPPh3)(SiMe3)(μ3-C)(μ2-AlMe2)(AlMe2)] 4, where the -AlMe2 moiety has been replaced by a non-coordinating SiMe3 one. Detailed electronic investigations (QTAIM, NBO, ETS-NOVC) suggest a Ti-C triple bond, with one AlMe2 moiety covalently bound to the carbon and the remaining three AlMex moieties interacting more in a Lewis acid-base fashion. Consequently, this is a penta-coordinated carbon and not, as the geometry would suggest, a penta-valent one.