Conversion of a Metallacyclobutene to Cobalt−Allene Complexes

Structures and Dynamic Solution Behavior of Cationic, Two‐Coordinate Gold(I)–π‐Allene Complexes

“…A number of late‐transition metal η 2 ‐allene complexes including Co I ,18 Os II ,19 Re I ,20 Rh I ,21, 22 Pd 0 ,23 Pt 0 ,24 Pt II ,22, 25 and Fe II[26] complexes have been structurally characterized. The allene ligands of these complexes display greater deviation from linearity (CCC=134–160°) and greater elongation of the complexed CC bond (1.35–1.43 Å) than is observed for gold–π‐allene complexes 1 a , 3 , and 4 (CCC164–166°, C1C2=1.33–1.35 Å).…”

A Fluorescence‐Based Screening Protocol for the Identification of Water Oxidation Catalysts

“…Downfield shifts for the substituent at the nitrogen atom (H30, C30) and upfield shifts of the substituent attached to the phosphorus atom (H23, C23) are observed in 5b with respect to 5a . Up to now, this effect was only known for allene complexes, described by O'Connor et al for [CpCo(PPh 3 ){η 2 ‐CH(SO 2 Ph)CCH(CO 2 Et)}] 57…”

Ruthenium-Mediated Cyclometalation Reactions of Allene and Allylphosphine C═C Bonds: Synthesis of κ(P),η4-(Hexa-2,5-dien-1-yl)diphenylphosphine–Ruthenium(II) Complexes

“…The high regio- and diasteroselectivity of these reactions represents the most interesting feature. Although it has been reported that metal allene complexes undergo two fluxional processes, rotation of the allene ligand about the metal–allene bond and migration of the metallic fragment along the orthogonal allene π-systems, ,, the NMR spectra of complexes 3 – 5 show the presence of a unique isomer. Thus, the presence of a single isomer for complex 3 at room temperature is evidenced by the observation of a singlet (42.3 ppm, 31 P NMR) and two methyl resonances (2.15 and 2.03 ppm, 1 H NMR; 28.2 and 22.5 ppm, 13 C NMR).…”

“…Thus, the broad resonance signal (38.1 ppm) observed at room temperature splits at low temperature (213 K) into three singlets (41.2, 38.4, and 35.9 ppm; relative intensity, 5:2:1) corresponding with species with κ( P )-coordination of the alkenylphosphine ligand. It is conceivable that two distinct, typical dynamic processes of η 2 -allene complexes (metal–olefin rotation and orthogonal 1,2,2-shift of the organometallic fragment) take place at room temperature (see Figure ).…”