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Compared with late transition metal alkyls, the corresponding metal alkoxides are difficult to prepare, especially if C-H bonds at the carbon connected to the oxygen atom are present. 1b Attempts to obtain these compounds by the displacement of halides or other good leaving groups from transition metal centers with alkali metal alkoxides (in analogy to the general method used to prepare metal alkyls) often lead to the corresponding metal hydrides. In fact, this occurs so frequently that the treatment of metal halides with alcoholic base is a classical method for preparing hydrides. 2 It is normally assumed, and in some cases established, 3-7 that aldehydes are produced in these reactions. This provides evidence that metal alkoxides are intermediates, but undergo rapid β-H elimination (eq 1, X ) halide, OTf).As in the related β-H eliminations of metal alkyls, it is normally assumed that a site of coordinative unsaturation cis to the alkoxo ligand is required for this process to occur. 3,5,8 Kinetically inert late transition metal complexes with M-O bonds have been prepared which lack R-oxy hydrogens, do not have an open coordination site, or have a sterically disfavored transition state for β-H elimination, 9 but for many systems, coordinatively saturated alkoxides are difficult to prepare or, once generated, are relatively unstable kinetically. 1,10 In a recent study of apparent ethylene insertion into a metalhydroxide bond, we proposed the binuclear complex (η 5 -C 5 -Me 5 )(PMe 3 )(Ph)Ir-CH 2 CH 2 -O-Ir(Ph)(PMe 3 )(η 5 -C 5 Me 5 ) as a crucial intermediate, and obtained evidence that its decomposition occurred by β-H elimination catalyzed by a third cationic iridium center. 11 Because this intermediate has an Ir-O bond at a formally coordinatively saturated iridium center, we considered the possibility that simpler iridium alkoxides might decompose by analogous metal-catalyzed mechanisms. Testing this possibil-

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These are turbulent times for much of chemistry as well as underlying global economies, but organometallic chemistry is heading higher, say the participants in the 2011 Organometallics Roundtable. In the inaugural version of this feature, our panelists take the pulse of the field, threshing out the big picture as well as the minutiae.

Reaction of Cp(PMe(3))IrPh(OH) (1) with nitriles is undetectably slow in benzene solution at room temperature. However, in the presence of Cp(PMe(3))IrPh(OTf) (2) (OTf = O(3)SCF(3)), the reaction is strongly catalyzed, leading to iridium(III) carboxamides Cp(PMe(3))IrPh[NHC(O)R] (6a-d) [R = C(6)H(4)CH(3) (6a), C(6)H(5) (6b), C(6)H(4)CF(3) (6c), CH(3) (6d)]. We propose that these transformations occur by initial displacement of the trifluoromethanesulfonate ("triflate") anion of 2 by a molecule of nitrile, leading to a nitrile-substituted iridium cation, [Cp(PMe(3))IrPh(NCR)](+) (10). Following this, the nucleophilic hydroxide group of 1 attacks the (activated) nitrile molecule bound in 10, leading (after proton transfer) to the iridium carboxamide complex. In the case of nitriles possessing hydrogens alpha to the cyano group, competitive loss of one of these protons is observed, leading to iridium C-bound cyanoenolates such as Cp(PMe(3))(Ph)Ir(CH(2)CN) (7). Protonolysis of carboxamides 6a-d with HCl yields Cp(PMe(3))IrPh(Cl) (9) and the free amides. A pronounced solvent effect is observed when the reaction between 1 and nitriles catalyzed by 2 is carried out in THF solution. The basic hydroxide ligand of 1 induces an overall dehydration/cyclization reaction of the coordinated aromatic nitrile. For example, the reaction of 1 with p-trifluorotolunitrile and a catalytic amount of 2 leads to the formation of 6c, water, [Ph(PMe(3))Ir[C(5)Me(4)CH(2)C(C(6)H(4)CF(3))N]] (12), and [Ph(PMe(3))Ir(C(5)Me(4)CH(2)C(C(6)H(4)CF(3))NH)]OTf (13). A mechanism to explain the formation of both 12 and 13 and the role each compound plays in the formation of the iridium carboxamides is proposed.