Combined high resolution X-ray and DFT Bader analysis to reveal a proposed Ru–H⋯Si interaction in Cp(IPr)Ru(H)2SiH(Ph)Cl

Penta-coordinated or -valent: the nature of the chemical bond of some Ti-C-Al compounds

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AlMe₃ ligand "removed" compared to 1, and [CpTi(μ²-NPPh₃)(SiMe₃)(μ³-C)(μ²-AlMe₂)(AlMe₂)] 4, where the -AlMe₂ moiety has been replaced by a non-coordinating SiMe₃ one.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 AlMe_x 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.

Detailed Density Functional Theory Study of the Cationic Zirconocene Compound [Cp(C5H4CMe2C6H4F)ZrMe]. ACS OMEGA 2022;7:35136-35152. [PMID: 36211080 PMCID: PMC9535714 DOI: 10.1021/acsomega.2c04053]

Detailed density functional theory studies at the B3LYP and PBE-D3 levels of theory were performed on the cationic compound [Cp(C₅H₄CMe₂C₆H₄F)ZrMe]⁺, with the F atom occupying either the ortho, meta, or para positions of the arene ring. In all cases, the arene ring coordinates with the cationic zirconium metal. The nature of this coordination is such that for the meta- or para-substituted arene ring, it is predominantly the ortho carbon atom of the C-H bond which interacts with the metal, as evident from noncovalent interaction studies. This is further corroborated by the natural bond orbital and quantum theory of atoms in molecular studies. In the case of the F atom being in the ortho position, we obtained clear-cut evidence for a Zr-F coordination.