CpIr complex

Oxidative addition of RX to square-planar Ir(CO)L2X or to CpIr(CO)L (L = PR3 or ASR3) invariably affords RIr(CO)L2X2 (71, 85, 86) and CpIr(CO)LR X (106, 198), respectively. Unlike some of their rhodium analogs, these complexes do not rearrange to the acyls. 

The gas-phase reactions of the cationic Irm complexes follow a previously unreported mechanism for their observed a-bond metathesis reactions. Previous discussions had considered a two-step mechanism involving intermolecular oxidative addition of either [Cp Ir(PMe3)(CH3)]+ or [CpIr(PMe3)(CH3)]+ to the C-H bond of an alkane or arene producing an Irv intermediate, followed by reductive elimination of methane, or a concerted a-bond metathesis reaction sim-... 

The intramolecular C—H activation of ethylene in complexes of the type CpIr(L)(QH4) is induced by uv irradiation and is favored over reaction with the solvent the process evidently involves a cage complex intermediate.118... 

The addition of alkanes to Ir111 species such as [CpIr(Me)L]+ can proceed via two pathways, oxidative addition (A) or or-bond metathesis akin to that in lanthanide complexes (B). 

The data in Tables 1-3 probably constitute the most extensive overview available for solution M-H BDE data that have been obtained by a single method. The effect of ancillary ligands on the M-H BDEs in series of related complexes can be studied in some detail. It was pointed out in Section 3.3.1 that the BDEs are remarkably insensitive to certain changes in the ligands. For example, within each of the following groups from Table 1, BDE differences are smaller than 8 kJ moL CpCr(CO)2(L)H (entries 1-4) CpW(CO)2(L)H (entries 12 and 13) Mn(CO)4(L)H (entries 17 and 18) Co(CO)3(L)H (entries 24-26) CpM(CO)3H compared with Cp M(CO)3H (M = Cr, entries 1 and 5 Mo, entries 8 and 9). Similar effects are found in Table 2 less than 5 kJ mol differences within the series CpIr(CO)(L)H+ (entries 32-39) Cp Ir(COD)H+ (entries 41-45) Cp Ir(CO)(L)H+ (entries 46-51, where the dicarbonyl differs somewhat more from the substituted compounds). 

That the ethene complex was the thermodynamic product, precludes it being an intermediate en route to the carbon-hydrogen activation product (the vinyl, hydride product ). Matrix isolation studies of CpIr(C2H4)PMe3 under photolysis showed isomerization to the vinyl, hydride complex . 

Rest and Graham reported in 1984 that the metal carbonyl complexes CpRh(CO)2, CpIr(CO)2, and Cp Ir(CO)2 can be deposited in methane matrices at 12 K and irradiated to give the corresponding methane oxidative addition products [28]. In addition, the dihydride CpIr(CO)H2 could be irradiated in a methane/argon matrix to generate CpIr(CO)(CH3)H by an alternative route [29]. While the dicarbonyl compounds were not efficient producers of the coordinatively unsaturated intermediate, Perutz found that CpRh(CO)(C2H4) lost... 

The reactions of Ir-carbonyl complexes with alkynes require more drastic conditions e.g., -CpIr(CO)2 reacts slowly at high temperature (120-160°C) with CF3C=CCF3 to form cis and trans isomers of the cr-bridging alkyne complex, ( / -HCp)2lr2(CO)2(CF3C2CF3) Several mononuclear r/ -alkyneiridium complexes are known ... 

Experimental results of Heinekey et al. show that the exchange coupling of [CpIr(L)H3] trihydride complexes increases when the 7i-acceptor character of the ligand L is enhanced [28]. To study this effect we applied the combined... 

Figure 12. Temperature dependence of the quantum exchange coupling for the [CpIr(CO)H3] complexes (a) L = PH. (b) L = CO...

The theoretical calculations using density functional theory showed that the intermolecular C-H activation of alkanes by the complex CpIr(PMc3)(CH3) (described by Bergman, vide supra) is a lower-energy process and that both inter- and (nfronolecular C-H activation proceed only through an oxidative-addition mechanism (Scheme VI.8) [64] (compare Scheme VI.7). 

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