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Reaction between the cationic iridacyclopentadiene complex [Ir(C4H4)(NCMe)(CO)(PPh3)2][CF3SO3] (1) and methylpropiolate produces the cationic iridabenzofuran [Ir(C7H5O{OMe-7})(CO)(PPh3)2][CF3SO3] (2) in high yield. On treatment of 2with chloride, the carbonyl ligand is displaced and the corresponding neutral iridabenzofuran Ir(C7H5O{OMe-7})Cl(PPh3)2(3) is formed. The fused metallacyclic rings of the iridabenzofurans 2and 3bear only one substituent (OMe), and therefore these compounds are well suited for studies of electrophilic aromatic substitution reactions. Bromination of cationic 2with pyridinium tribromide proceeds to give the monobrominated iridabenzofuran [Ir(C7H5O{OMe-7}{Br-6})(CO)(PPh3)2][CF3SO3] (4) exclusively. Bromination of neutral 3with the same reagent gives the dibrominated iridabenzofuran Ir(C7H5O{OMe-7}{Br-6}{Br-2})Br(PPh3)2(5) exclusively. Treatment of compound 3with mercury(II) trifluoroacetate followed by excess bromide (to displace coordinated trifluoroacetate) produces the trimercurated iridabenzofuran Ir(C7H5O{OMe-7}{HgBr-6}{HgBr-4}{HgBr-2})Br(PPh3)2(6). The three Hg−C bonds in 6are readily cleaved on addition of pyridinium tribromide, and the resulting product is the tribrominated iridabenzofuran Ir(C7H5O{OMe-7}{Br-6}{Br-4}{Br-2})Br(PPh3)2(7). These regioselective mono-, di-, and trifunctionalization reactions of iridabenzofurans have been studied by DFT calculations, and the derived condensed Fukui functions have been used to rationalize the preferred sites for electrophilic attack. The crystal structures of 2−7have been obtained. [ABSTRACT FROM AUTHOR]

Reversible protonation of the purple ruthenabenzofuran (or tethered ruthenacyclohexadiene) Ru[C5H2(CO2Me-2)(CO2Me-4)(CHCO2Me-5)](CO)(PPh3)2(1) with HBF4·OEt2gives the structurally characterized stable cationic tethered ruthenabenzene [Ru[C5H2(CO2Me-2)(CO2Me-4)(CH2CO2Me-5)](CO)(PPh3)2][(BF4)2H] (2), while the thermal reaction of 1with HCl forms the stable neutral tethered ruthenabenzene Ru[C5H2(CO2Me-2)(CO2Me-4)(CH2CO2Me-5)]Cl(PPh3)2(3) as the major product. The cyclopentadienyl complex Ru(η5-C5H2(CH2CO2Me-1)(CO2Me-2)(CO2Me-4)Cl(CO)(PPh3) (4), which is formed in this reaction as a minor product, can be separated from 3by chromatography. Treatment of the ruthenabenzene 3with CNR (R = p-tolyl) gives the purple ruthenabenzofuran (or tethered ruthenacyclohexadiene) complex Ru[C5H2(CO2Me-2)(CO2Me-4)(CHCO2Me-5)](CNR)(PPh3)2(5), which is the isocyanide analogue of 1. [ABSTRACT FROM AUTHOR]

The cationic thiocarbonyl complex [Ir(CS)(MeCN)(PPh 3) 2][CF 3SO 3] ( 1) reacts sequentially with ethyne and LiCl to give the iridacyclopentadiene Ir[C 4H 4]Cl(CS)(PPh 3) 2( 2), which in turn when heated with methyl triflate followed by addition of LiCl produces the stable, purple, iridabenzene Ir[C 5H 4(SMe-1)]Cl 2(PPh 3) 2( 3). This iridabenzene undergoes electrophilic aromatic bromination in the position parato the SMe substituent to form Ir[C 5H 3(SMe-1)(Br-4)]Br 2(PPh 3) 2( 4). [ABSTRACT FROM AUTHOR]

Treatment of IrCl(CS)(PPh3)2with an excess of KI gives orange IrI(CS)(PPh3)2(1). IrI(CS)(PPh3)2(1) reacts reversibly with dioxygen to form the brown dioxygen complex Ir(O2)I(CS)(PPh3)2(2). Reaction between IrI(CS)(PPh3)2(1) and 2 equiv of ethyne produces the green-brown tethered iridacyclobutadiene complex IrC3H2(CHCHS-1)I(PPh3)2(3), one ethyne combining in a cycloaddition reaction with the IrC multiple bond to the CS ligand to form the four-membered IrC3ring and the second ethyne alkylating the sulfur atom to give the vinylthio substituent at the 1-position of the metallacyclic ring, which is tethered to the iridium through an Ir−C bond. In reactions related to those with ethyne, phenylacetylene reacts with IrCl(CS)(PPh3)2to give as the major product the tethered iridacyclobutadiene IrC3H(CHCPhS-1)(Ph-3)Cl(PPh3)2(4), with the phenyl substituent adjacent to the iridium, and as the minor product the isomeric tethered iridacyclobutadiene IrC3H(CHCPhS-1)(Ph-2)Cl(PPh3)2(5). A thermal reaction of IrC3H(CHCPhS-1)(Ph-3)Cl(PPh3)2(4) with further phenylacetylene produces the tethered, substituted cyclopentadienyliridium complex Ir5-C5H2(SCPhCH-1)(Ph-3)(Ph-5)Cl(PPh3) (6), which retains the iridium−carbon bond to the vinylthio substituent. Methyl propiolate reacts with IrI(CS)(PPh3)2(1) to form exclusively the tethered iridacyclobutadiene IrC3H(CHCCO2MeS-1)(CO2Me-2)I(PPh3)2(7). Treatment of this iridacyclobutadiene, 7, with silver triflate allows introduction of a third methyl propiolate, which brings about ring expansion of the iridacyclobutadiene to form the stable tethered iridabenzene IrC5H2(CHCCO2MeS-1)(CO2Me-2)(CO2Me-4)Cl(PPh3)2(8). Complex 8retains the same vinylthio tethering group as found in 7. The structures of 2−8have been confirmed by X-ray crystal structure determinations. Both NMR spectroscopic and structural data for 8support the formulation of this compound as a tethered metallaaromatic molecule. [ABSTRACT FROM AUTHOR]