Complexes of metal ions with phosphorus or arsenic containing ligands

Furans Bound Face‐On: Sequential Loss of CO in the Formation of [W(CO)4(η4‐2,5‐dimethylfuran)]

“…The only other [W(CO) 5 (h 1 -L)] (L = cyclic ether) complexes that we had previously observed to be unstable on a time scale of seconds are those in which the ligand also contains a double bond. [12] Following their initial formation from [W(CO) 5 (CyH)], these complexes undergo an intramolecular linkage isomerization to yield [W(CO) 5 (h 2 -L)], in which the ligand is bound to the metal by means of its double bond.…”

“…[4] We report here the observation of a carbonyl-containing h 4 -furan complex, [W(CO) 4 (h 4 -Me 2 Fur)] 2 (Me 2 Fur = 2,5-dimethylfuran), and the results of a kinetic study of its formation from [W(CO) 5 It has long been known that photolysis of [M(CO) 6 ] (M = Cr, Mo, W) in the presence of a bischelating ligand (L 2 ) produces [M(CO) 4 (L 2 )]. [5] Technological advances made over the past two decades have made it possible to investigate the details of the reaction by means of the techniques of "fast kinetics." Such studies have shown that the reaction proceeds in several steps: first, the pentacarbonyl complex formed by the initial photolysis reacts within tens of picoseconds to form a solvated intermediate [M(CO) 5 (solv)] (solv = a molecule of solvent).…”

“…[5] Technological advances made over the past two decades have made it possible to investigate the details of the reaction by means of the techniques of "fast kinetics." Such studies have shown that the reaction proceeds in several steps: first, the pentacarbonyl complex formed by the initial photolysis reacts within tens of picoseconds to form a solvated intermediate [M(CO) 5 (solv)] (solv = a molecule of solvent). [6] This solvated intermediate reacts with a molecule of L 2 to produce a monodentate complex [M(CO) 5 (L-L)], which then undergoes a thermally activated intramolecular ligand exchange, on a much slower timescale, to form the bidentate complex [M(CO) 4 (L 2 )].…”

“…[10] We have previously reported [11c] that in the presence of excess Me 2 Fur, [W(CO) 5 [11c] we assigned to it the h 1 structure 1, that is, the ligand is bound to the metal through the lone pair of the O atom. We also determined the activation parameters for the reaction to be DH°= 26.…”

High yield synthesis and structures of some achiral and chiral (diphosphine)tetracarbonylchromium(0) chelate complexes with tetracarbonyl(norbornadiene)chromium(0) as complexation reagent

“…25,26 Tetracarbonyl[1,4-bis(diphenylphosphino)butane]chromium(0) (4). 10 Crystal structure analysis of 5. …”