84074-31-7

Upstream product

• 84074-30-6 iridium(η2-C8H14)(N(SiMe2CH2PPh2)2) 

Downstream Products

• 104874-24-0 Ir(CH₃)I(CO)(N(Si(CH₃)2CH₂P(C₆H₅)2)2) 

Relevant academic research and scientific papers

Synthesis and reactivity of the coordinatively unsaturated methylene complex Ir=CH2[N(SiMe2CH2PPh2)2]

The reactions of the coordinatively unsaturated iridium methylene complex Ir=CH2[N(SiMe2CH2PPh2)2] are described. This methylene complex is prepared by the reaction of 2 equiv of KOBut with the methyl iodide derivative Ir(CH3)I[N(SiMe2CH2PPh2) 2] in toluene; the extra equivalent of KOBut serves to coordinate the HOBut that is produced as the precipitate KOBut·-HOBut. The reaction of H2 with the methylene complex generates the trihydride amine IrH3[HN(SiMe2CH2PPh2)2] via a series of oxidative addition and migratory insertion steps; the trihydride derivative loses H2 upon workup to generate the iridium(III) dihydride IrH2[N(SiMe2CH2PPh2)2]. The reaction of the methylene complex with PMe3 produces the square planar PMe3 derivative Ir(PMe3)[N(SiMe2CH2PPh2) 2] and ethylene (0.5 equiv); monitoring this reaction at low temperatures shows the presence of a number of intermediates that suggest the mechanism involves the generation of free H2C=PMe3 which reacts with the methylene complex to ultimately give the observed products. The reaction of the methylene complex with CO results in the formation of Ir(CO)[(CH2PPh2CH2SiMe2NSiMe 2CH2PPh2)], in which the methylene unit has inserted into one of the iridium-phosphine bonds of the ancillary tridentate ligand. Also produced in this reaction is a small and variable amount (≤15%) of the iridium(I) carbonyl complex Ir(CO) [N(SiMe2CH2PPh2)2]; the fate of the coordinated methylene unit for this side reaction could not be determined. Oxidative addition reactions were also examined; addition of Al2Me6 to the methylene derivative resulted in the formation of the hydride-aluminum complex Ir(μ-AlMe2)H[N(SiMe2-CH2PPh 2)2]; this heterobimetallic species has the AlMe2 unit directly bound to iridium and bridged by the amide donor of the backbone. A mechanism is proposed that involves oxidative addition of AlMe3 to the iridium center followed by migratory insertion of the methylene unit and the methyl to generate an ethyl ligand which β-eliminates and releases ethylene to generate the hydride. The methylene complex also reacts with methyl iodide to generate the ethylene hydride iodide complex Ir(η2-C2H4)H(I)[N(SiMe2CH 2PPh2)2]; the proposed mechanism also involves oxidative addition as the first step followed by migratory insertion to generate an ethyl moiety; however, rather than simple β-elimination to the iridium center, the amide unit abstracts the β-hydrogen to form an amine-olefin complex that subsequently inverts at nitrogen and then oxidatively adds the N-H unit to generate the hydride complex. Deuterium-labeling experiments show that the abstraction of the β-hydrogen is reversible since there is scrambling of the label equally into both the α and β positions of the coordinated ethylene.

Thermal and photochemical transformations of organoiridium phosphide complexes. Mechanistic studies on carbon-phosphorus bond formation to generate cyclometalated hydride complexes by α-hydride abstraction

The thermal and photolytic transformations of a series of methyliridium(III) phosphide complexes are described. Complexes of the formula Ir(CH3)PR2[N(SiMe2CH2PPh 2)2] (R = Ph, Me) rearrange thermally to generate the corresponding cyclometalated derivatives fac-Ir(η2-CH2PR2)H[N(SiMe 2CH2PPh2)2]; continued thermolysis results in the formation of the iridium(I) phosphine complexes Ir(PMeR2)[N(SiMe2CH2PPh2) 2]. Under photolytic conditions the phosphide derivatives rearrange directly to the phosphine complexes with no observable intermediates. The phenylphosphide complex Ir(CH3)PHPh[N(SiMe2CH2PPh2) 2] rearranges directly to the phosphine derivative Ir(PHPhMe)[N(SiMe2CH2PPh2)2] both thermally and photolytically with no observable intermediates. Crystals of Ir(CH3)PPh2[N(SiMe2CH2PPh 2)2] are monoclinic with a = 13.506 (3) A?, b = 13.665 (3) A?, c = 22.816 (7) A?, β= 92.35 (2)°, Z = 4, Dc = 1.454 g cm-3, and space group P21/c. The structure was solved by the Patterson method and refined by full-matrix least-squares procedures to R = 0.034 and Rw = 0.037 for 3993 reflections with I ≥ 3σ(I). Crystals of fac-Ir(η2-CH2PPh2)H[N(SiMe 2CH2PPh2)2] are monoclinic with a = 9.253 (2) A, b = 21.950 (5) A?, c = 20.081 (4) A?, β= 90.74 (2)°, Z = 4, Dc = 1.50 g cm-3, and space group P21/c. The structure was solved by conventional heavy-atom techniques and was refined in blocks (with the Ir atom in every cycle) by using least-squares procedures down to R = 0.0356 and Rw = 0.0370 for 4448 reflections with I ≥ 3σ(I). Mechanistic studies showed that the formation of the cyclometalated hydride does not involve reductive transfer of the methyl and the phosphide ligands to form a phosphine complex followed by intramolecular C-H bond activation, rather C-H bond abstraction occurs first followed then by C-P bond formation. Transition-state arguments are used to rationalize the difference in the reactivity of the phenylphosphide complex for which no cyclometalated intermediate was detected.

Rhodium and iridium amides

A series of Rh(I) and Ir(I) amide complexes has been prepared and characterized; all of these M(L)-[N(SiMe2CH2PR2)2] (M = Rh, Ir; L = C8H14, C2H4, CO, PMe3, PPh3) species are square-planar with the tridentate amide ligand phosphine donors in a mutually trans disposition. Oxidative addition of CH3I or CH3Br to the M(I) cyclooctene amides results in five-coordinate M(III) derivatives M(CH3)X[N-(SiMe2CH2PR2)2] (M = Rh, Ir; X = I, Br; R = Ph, i-Pr). On the basis of nOe difference 1H NMR experiments and crystallographic data, these M(III) amides are thought to have a square-pyramidal stereochemistry both in the solid state and in solution. Monoclinic Ir(CH3;)I[N(SiMe2CH2P(i-Pr)2) 2] crystallizes in the P21/m space group with Z = 2, a = 9.6295 (7) ?, b = 15.2327 (5) ?, and c = 10.4068 (8) (?); Rw = 0.029. Spectroscopic information regarding the CO adducts M(CO)(CH3)X[N(SiMe2CH2PR2)2], formed by exposure to the M(III) amides to carbon monoxide under ambient conditions, indicates that the five-coordinate complexes maintain their square-pyramidal stereochemistry in solution.