Formation and reactivity of organometallic alkane complexes

Rhodium complexes in homogeneous catalytic systems for oxidative functionalization of alkanes: Experiment and quantum-chemical calculations

“…The absence of H-D exchange with the medium is compatible with mechanism (9)-(10), at the same time not being inconsistent with the alternative mechanism [20,21] involving formation of the Rh-CH 3 bond via σ-complex 2 (Scheme 4). By analogy with π-complexes of alkenes, we can expect that in σ-complexes the C-H bond gets weakened, which is followed by electron transfer to ligand OI -to yield organometallic derivatives 3 and 4.…”

A Rhodium–Pentane Sigma‐Alkane Complex: Characterization in the Solid State by Experimental and Computational Techniques

“…Thep rincipal component is observed as two sets of doublets centered at d = 107. 6 [13,14,22] At 223 Kt he spectra remain unchanged overnight, but on warming to 298 K( 12 hrs), 4 grows in at the expense of [3][BAr F 4 ], demonstrating that the pentane complex is thermally unstable ( Figure S8). This instability can also be followed by single-crystal X-ray diffraction, which shows arelatively rapid (15 minutes at 298 K) loss of high-angle data on warming ( Figure S13).…”

“…[3,4] Owing to the strong, non-polar,C ÀHb ond, and steric interactions from proximal alkyl groups,alkanes are poor ligands, [5] meaning that solvent or other Lewis bases can compete for metal coordination. Direct observation of alkane complexes in solution thus requires low temperatures (typically 130-190 K) and spectroscopic techniques,s uch as time-resolved infrared spectroscopy (TRIR) [6] or in situ NMR spectroscopy, [7] and is often (although not exclusively [8] )based on reversible ligand photoejection. When this relative instability is coupled with the less than 100 %efficiency often associated with the generation of s-alkane complexes,t he production of single-crystalline material suitable for detailed structural characterization is very challenging.Nevertheless,initially serendipitous,singlecrystal X-ray diffraction studies have shown alkane CÀH bonds in close approach with metal centers (Fe 2+ , [9] U 3+ , [10] K + [11] ), in which host-guest interactions with alkane ligands are suggested to play an important role.W erecently reported an alternative approach for the targeted generation of a salkane complex by solid/gas single-crystal to single-crystal transformations [12] …”

Contrasting electronic requirements for CH binding and CH activation in d6 half‐sandwich complexes of rhenium and tungsten

“…[7][8][9] Several metalalkane complexes have been discovered since then using spectroscopic techniques such as Time Resolved Infra Red (TRIR) and Nuclear Magnetic Resonance (NMR) spectroscopy with photoirradiation in solution. Early work in this area has been extensively reviewed, [10][11][12][13][14] and we highlight only three major areas that are the subject matter of this computational study.…”