| Abstract
| - A series of (allenylidene)iridium(I) complexes trans-[IrX{CCC(Ph)R}(PiPr3)2] (X = F, Br, I, NCO, NCS, OPh, N3) were prepared either from the corresponding chloro derivatives by salt metathesis or from the hydroxo compounds by acid−base reactions. The azido as well as the phenolato complexes react with CO by migratory insertion of the C3 unit into the Ir−N or Ir−O bond. An unprecedented type of insertion occurs by treatment of the hydroxo compounds with excess of 1-alkynes HC⋮CR‘, which leads to the formation of the novel five-coordinate iridium(III) complexes [Ir(C⋮CR‘)2{η1-(E)-CHCR‘−CHCC(Ph)R}(PiPr3)2]; the molecular structure of one of these is shown.
- A series of (allenylidene)iridium(I) complexes of general composition trans-[IrX{CCC(Ph)R}(PiPr3)2] [X = Br (5), I (6), NCO (7, 8), NCS (9, 10), OH (11, 12), N3 (13, 14)] wasprepared from the corresponding chloro derivatives trans-[IrCl{CCC(Ph)R}(PiPr3)2] (3,4) by salt metathesis. An X-ray crystal structure analysis of 4 (R = Ph) confirmed the almostlinear arrangement of the Ir−C−C−C chain. The azido compounds 13 (R = Ph) and 14 (R= tBu) react with CO by migratory insertion of the allenylidene ligand into the Ir−N3 bond.While the product trans-[Ir{C≡C−CR(Ph)N3}(CO)(PiPr3)2] with R = tBu (16) is thermallystable, the related complex with R = Ph (15) rearranges slowly in benzene to the metalatedacrylonitrile derivative trans-[Ir{C(CN)CPh2}(CO)(PiPr3)2] (17) by elimination of N2.Treatment of the phenolato compound trans-[Ir(OPh){CCC(Ph)tBu}(PiPr3)2] (19),obtained from the analogous hydroxo derivative 12 and phenol, with CO also proceeds bymigratory insertion and affords the functionalized (alkynyl)iridium(I) complex trans-[Ir{C⋮C−CtBu(Ph)OPh}(CO)(PiPr3)2] (20) in excellent yield. The Lewis basicity of the hydroxocompounds 11 and 12 was also illustrated by the reactions with CF3CO2H, NEt3·3HF, and[pyH]BF4, which gave the substitution products trans-[Ir(κ1-O2CCF3){CCC(Ph)tBu}(PiPr3)2] (21), trans-[IrF(CCCPh2)(PiPr3)2] (22), and trans-[Ir{CCC(Ph)tBu}(py)(PiPr3)2]BF4 (23), respectively. In methanol solution, both 11 and 12 react by completefragmentation of 1 equiv of CH3OH to afford the octahedral (allenyl)dihydridoiridium(III)complexes [IrH2{CHCC(Ph)R}(CO)(PiPr3)2] (24, 25). An unprecedented type of insertionreaction occurs by treating the hydroxo derivatives 11 and 12 with an excess of 1-alkynesR‘C⋮CH (R‘ = Ph, CO2Me), which leads to the formation of the novel five-coordinate iridium(III) compounds [Ir(C⋮CR‘)2{η1-(E)-CHCR‘−CHCC(Ph)R}(PiPr3)2] (26−29). From 26,27 (R‘ = Ph), and CO, the octahedral 1:1 adducts 30 and 31 are formed. The molecularstructures of 22 and 26 have been determined by X-ray crystallography.
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