Tris(Butadiene) Compounds versus Butadiene Oligomerization in Second-Row Transition Metal Chemistry: Effects of Increased Ligand Fields

Molecules

RobertBruce King¹  HenryF. Schaefer¹  Yaoming Xie¹  Xuejun Feng²  Qun Chen²  Mingyang He²  Zhihui Zhang²  Yi Zhao² 

[1] Department of Chemistry and Center for Computational Quantum Chemistry, University of Georgia, Athens, GA 30602, USA;School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China;

关键词: butadiene complexes;    transition metals;    density functional theory;   

DOI  :  10.3390/molecules26082220

来源: DOAJ

【 摘 要 】

The geometries, energetics, and preferred spin states of the second-row transition metal tris(butadiene) complexes (C₄H₆)₃M (M = Zr–Pd) and their isomers, including the experimentally known very stable molybdenum derivative (C₄H₆)₃Mo, have been examined by density functional theory. Such low-energy structures are found to have low-spin singlet and doublet spin states in contrast to the corresponding derivatives of the first-row transition metals. The three butadiene ligands in the lowest-energy (C₄H₆)₃M structures of the late second-row transition metals couple to form a C₁₂H₁₈ ligand that binds to the central metal atom as a hexahapto ligand for M = Pd but as an octahapto ligand for M = Rh and Ru. However, the lowest-energy (C₄H₆)₃M structures of the early transition metals have three separate tetrahapto butadiene ligands for M = Zr, Nb, and Mo or two tetrahapto butadiene ligands and one dihapto butadiene ligand for M = Tc. The low energy of the experimentally known singlet (C₄H₆)₃Mo structure contrasts with the very high energy of its experimentally unknown singlet chromium (C₄H₆)₃Cr analog relative to quintet (C₁₂H₁₈)Cr isomers with an open-chain C₁₂H₁₈ ligand.

【 授权许可】

Unknown