Influence of chelate substituents on the structure and spin state of unsaturated [N(SiMe2CH2PtBu2)2]Ru-X

Density functional theory calculations on the conformational preferences in the two fused five-membered rings of anionic N(SiR2CH2PR'2)2 chelated to RuX+ are compared to several experimental structures (X=halide). The calculations consider the structures of both singlet and triplet states and reveal that both the four tBu groups and the crowded juncture (N(SiMe2)2) of the two rings must be included computationally to understand the observed structures. Computational experiments with different substituents R and R' show the reality of N-->Ru pi donation. The cases where X=H and CH3 are also studied.