Quo Vadis, agostic bonding?

Abstract

The role of agostic bonds in chemistry is highlighted. In particular, attention is given to the origin of the term, methods of investigations and their function in chemistry.

Spontaneous Bicyclometalation of a Single Cobalt(I) Complex Stabilized by a δ‐C–H Agostic Interaction

“…By the interaction with (1)···H (1) 1.69(8), Co(1)-C(1) 2.161(2), Co(1)-C(7) 1.909 (1), Co(1)-P(1) 2.181(3), Co(1)-P(2) 2.223(3), Co(1)-P(3) 2.161(3), C(7)-N(1) 1.302(9); Co (1)···H (1)···C (1) 106.9(3), C(1)-Co (1) (1)-H(1) distance [1.69(8) Å] is within the range observed for other agostic cobalt complexes. [15,18,19] Similar bond length parameters of 1 are detected for 4d and 5d-transition metals, [20] with pincer type ligands. [21] This rarely observed double C-H activation delivers a metallabicycle with an agostic interaction.…”

Variation of M···H–C Interactions in Square-Planar Complexes of Nickel(II), Palladium(II), and Platinum(II) Probed by Luminescence Spectroscopy and X-ray Diffraction at Variable Pressure

“…17 Examples of intermolecular M ... H-C interactions have been reported for square-planar platinum(II) and palladium(II) complexes. 21 22 These interactions are the focus of reports from several areas, [23][24][25] including crystal engineering 26,27 or C-H activation. 28,29 Experimental examples of such effects are often measured at a single set of conditions, which gives limited insight on the interaction and the effect of different metal centers.…”

[Pt(SCN)4]2–‐Based Coordination Polymers and Supramolecular Squares: Intermolecular Pt···H–C Interactions Probed by Luminescence Spectroscopy at Variable Pressure

“…Our results illustrate that this is an addition to the experimental techniques used to characterize such interactions, up to now characterized predominantly by X‐ray crystallography and to a lesser extent by NMR or vibrational spectroscopy , . The study of interactions between C–H bonds and electron deficient metal centers, or electron rich aromatic π systems, has a long history , . The nature of the M ··· H interaction has been classified as agostic or anagostic interactions .…”