Synthetic, structural, and spectroscopic studies of mixed sandwich Ru(II) complexes involving η⁶-p-cymene with monodentate fluorine-containing phosphines or phosphites

Abstract

Syntheses, structures, spectroscopy, and calculated structures for several Ru(II) complexes involving p-cymene and either fluorine-containing phosphines or phosphites are reported. The complexes are readily prepared by ligand substitution reactions from [{Ru(p-cymene)Cl₂}₂] to produce [Ru(p-cymene)(L)Cl₂] {L = P(C₆H₄-p-F)₃ (1), P(C₆H₄-p-CF₃)₃ (2), P(C₆H₃(m-CF₃)₂)₃ (3), PPh₃ (4), P(OCH₂CF₃)₃ (5), P(OCH(CF₃)₂)₃ (6), and POMe₃ (7)}. The structures for all seven complexes are supported by UV–vis and multi-nuclear NMR spectroscopy. Five complexes are characterized by single-crystal X-ray crystallography (1, 3, 5–7) and exhibit a distorted octahedral structure involving three donors from one phosphine or phosphite ligand, two chlorides, and the facially coordinating η⁶-p-cymene ligand. Electronic structure theory computations have been performed on 1–7 along with the theoretical [Ru(p-cymene){P(C₆F₅)₃}Cl₂] (8). For all complexes, the HOMO is primarily Ru (d_xy or ) in character. The LUMO shifts from primarily Ru (d_xz or d_yz) to primarily phosphine ligand π* as the number of fluorines increases.

Keywords:

• p-Cymene
• Ru complexes
• fluorine
• phosphine ligands
• phosphite ligands
• crystal structures

Acknowledgments

The single-crystal X-ray diffraction structures were solved and refined at the 2013 American Crystallographic Association Single-Crystal X-Ray Crystallography Course at Northwestern University. Also, Patrick Zdunek (UTC) is thanked for his work obtaining the variable temperature ¹H NMR spectra.

Disclosure statement

No potential of conflict of interest was reported by the authors.