98720-65-1

Upstream product

• 15318-31-7 bis(triphenylphosphine)iridium(I) carbonyl chloride 
• 865-48-5 sodium t-butanolate 

Downstream Products

• 98735-49-0 (CH₃)3COC(O)Ir(CO)2(P(C₆H₅)3)2 
• 16971-55-4 IrH₃(CO)(PPh₃)₂ 
• 75-97-8 3,3-dimethyl-butan-2-one 
• 17250-59-8 HIr(PPh₃)2(CO)2 
• 107-31-3 Methyl formate 
• 762-75-4 tert-butyl formate 

Relevant academic research and scientific papers

Mechanism of β-hydrogen elimination from square planar iridium(I) alkoxide complexes with labile dative ligands

Mechanistic studies were conducted on β-hydrogen elimination from complexes of the general formula [Ir(CO)(PPh3)2(OR)], which are square planar alkoxo complexes with labile ligands. The dependence of rate, isotope effect, and alkoxide racemization on phosphine concentration revealed unusually detailed information on the reaction pathway. The alkoxo complexes were remarkably stable, including those with a variety of electronically and sterically distinct groups at the β-carbon. These complexes were much more stable than the corresponding alkyl complexes. Thermolysis of these complexes in the presence of PPh3 yielded the iridium hydride [Ir(CO)(PPh3)3H] and the corresponding aldehyde or ketone with rate constants that were affected little by the groups at the β-carbon. The reactions were first order in iridium complexes. At low [PPh3], the reaction rate was nearly zero order in PPh3, but reactions at high [PPh3] revealed an inverse dependence of reaction rate on PPh3. The rate constants were similar in toluene, THF, and chlorobenzene. The y-intercept of a 1/kobs VS [PPh3] plot displayed a primary isotope effect, indicating that the y-intercept did not simply correspond to phosphine dissociation. These data and a dependence of alkoxide racemization on [PPh3] showed that the elementary β-hydrogen elimination step was reversible. A mechanism involving reversible β-hydrogen elimination followed by associative displacement of the coordinated ketone or aldehyde by PPh3 was consistent with all of our data. This mechanism stands in contrast with the pathways proposed recently for alkoxide β-hydrogen elimination involving direct elimination, protic catalysts, or binuclear mechanisms and shows that alkoxide elimination can follow pathways similar to those for β-hydrogen elimination from alkyl complexes.

Formation of carboalkoxyiridium complexes by carbonylation of alkoxyiridium complexes and the crystal structure of trans-PhOIr(CO)(PPh3)2

The preparation of iridium alkoxide complexes trans-ROIr(CO)(PPh3)2 and their carbonylation to carboalkoxy complexes ROC(O)Ir(CO)2(PPh3)2 are described for R = Me, n-Pr, t-Bu, and Ph. The preparations involve metathetical reactions between trans-Ir(CO)(PPh3)2Cl and NaOR. In the carbonylation an intermediate can be identified by infrared and conductivity studies as [Ir(CO)3(PPh3)2+][OR-]. Thus a mechanism involving alkoxide displacement by CO and subsequent nucleophilic attack of alkoxide on a CO of the cation is indicated. The complex trans-PhOIr(CO)(PPh3)2 crystallizes in the centrosymmetric monoclinic space group P21/c (no. 14) with a = 15.790 (3) ?, b = 11.461 (3), c = 19.986 (5) ?, β = 100.326 (18)°, V = 3558 (2) ?3, and Z = 4. Diffraction data (Mo Kα, 2θ = 5-55°) were collected with a Syntex P21 automated four-circle diffractometer, and the structure was solved and refined to RF = 6.2% and RwF = 4.6% for all 8220 reflections (RF = 3.8% and RwF = 4.1% for those 5981 reflections with |F0| > 6σ(|F0|)). The iridium atom has the expected square-planar geometry with Ir-P(1) = 2.328 (1) ?, Ir-P(2) = 2.344 (1) ?, Ir-CO = 1.795 (5) ?, and Ir-OPh = 2.049 (4) ?. The phenoxide ligand is "bent" with 〈Ir-O-C(ipso) = 126.5 (3)°.