Transition‐Metal Complexes with (C–C)→M Agostic Interactions

Abstract

The coordination of sigma bonding electron density to a Lewis acid was for some time largely the domain of boron hydride chemistry. Subsequently it was found that C-H bonds could undergo intramolecular coordination to metal centers, forming what are now known as "agostic bonds" and "agostic complexes". Thereafter, even the H-H bond in molecular hydrogen was found to be capable of coordination, leading to what are commonly referred to as "sigma complexes". Eventually, coordination by much more shielded C-C bonds was estab-[a] US Navy, Naval inorganic chemistry from the University of Utah in 2005, studying with Professor Richard D. Ernst. His graduate studies were focused on the synthesis and characterization of early-transition-metal organometallic cage structures and metallacyclobutanes. Many of the compounds studied in his research exhibited unique C-C agostic bonding interactions. His current areas of interest include catalysis, advanced biofuels, high-temperature thermosetting resins, and green chemistry. Richard D. Ernst is a Professor of Chemistry at the University of Utah. He received his B.S. degree in chemistry from the University of California in Berkeley in 1973 and his Ph.D. degree in inorganic chemistry from Northwestern University in 1977. His major areas of interest include organometallic chemistry, particularly of metal-pentadienyl compounds, coordination chemistry, and catalysis of the Fischer-Tropsch and Water Gas Shift reactions.

Metathesis by Partner Interchange in σ‐Bond Ligands: Expanding Applications of the σ‐CAM Mechanism

“…Once considered exceedingly rare, s-bond complexes that involve EÀEbonds (e.g.B ,C,Si) have peppered the literature over the last 15 years. [94,95] While still relatively uncommon, such interactions are now firmly established, and have been characterized by structural (single crystal X-ray diffraction), spectroscopic (NMR) and computational (DFT/QTAIM) techniques.S elected examples are included here to highlight key advances,alongside the various descriptors that are used to identify EÀE s-bond coordination. .…”

Chasing the agostic interaction in ligand assisted cyclometallation reactions of palladium(ii)

“…Complexes in which C-Cσ bond electron density donates to metal centres have been termed 'C-C agostic interactions'. 31 NBO orbital 2D contour plots and 3D spatial images diagrams for the two interactions involving the aromatic ring C7-C8π orbitals are shown in Fig. 7.…”

Carbozincation of Substituted 2-Alkynylamines, 1-Alkynylphosphines, 1-Alkynylphosphine Sulfides with Et2Zn in the Presence of Catalytic System of Ti(O-iPr)4 and EtMgBr

“…Presumably, one of the factors responsible for the observed non-selective transformation of cyclopropyl-substituted alkynylphosphine sulfide is the presence of C-C agostic interaction between the titanium atom and cyclopropane ring. The agostic interaction involving cyclopropane moieties was reported for Pt complexes, such as [PtCl 2 (c-C 3 H 6 )] 2 and PtCl 2 (c-C 3 H 6 )(py) 2 (py = pyridine) [17], and for lithium cyclopropoxide complex [18,19].…”