New Titanium Carbonyls: Ti₂(CO)₁₀, Ti₂(CO)₁₁, and Ti₂(CO)₁₂

Abstract

Structural and energetic features of the binuclear titanium carbonyls Ti2(CO)n (n = 12, 11, 10) have been examined using density functional theory. The lowest-energy Ti2(CO)12 structure is a singlet structure consisting of two Ti(CO)6 units linked by Ti═Ti double bonds of lengths 3.0-3.2 Å. A similar slightly higher energy triplet Ti2(CO)12 structure is found with longer Ti-Ti bonds (3.37-3.62 Å), considered to be formal single bonds. The energy required for the dissociation of Ti2(CO)12 into two Ti(CO)6 fragments is 18.5 ± 2 kcal/mol higher than the energy required for the dissociation of V2(CO)12 into two V(CO)6 fragments. For the unsaturated Ti2(CO)11 system, the lowest-energy structures contain a four-electron-donor bridging η(2)-μ-CO group and 10 terminal CO groups with formal Ti═Ti double bonds in the singlet structures and formal Ti-Ti single bonds in the triplet structures. Similarly, the most favored geometries for the more highly unsaturated Ti2(CO)10 contain two four-electron-donor bridging η(2)-μ-CO groups with formal Ti═Ti double bonds for the singlet structures and formal Ti-Ti single bonds for the triplet structures. Higher-energy triplet Ti2(CO)10 structures are found with two or three two-electron-donor semibridging CO groups and formal Ti≡Ti triple bonds of length 2.7-2.8 Å.

Infrared Photodissociation Spectroscopy of Heteronuclear Arsenic–Iron Carbonyl Cluster Anions

“…Natural bond orbital (NBO) analysis was performed to study the atomic electronic charge distributions and bonding character of the cluster anions. The hybrid functional B3LYP, pure functional BP86, and meta -GGA functional TPSS are among the most popular density functionals and have proven to provide reliable predictions on the structures and vibrational frequencies of arsenic clusters and transition-metal-containing clusters. ,− Throughout the calculation process, the three functionals agreed well in their isomer location predictions. To be consistent with our previous studies, − the optimized structures and the frequencies obtained using the B3LYP functional were used unless stated otherwise.…”