154. The tautomerism of arene and ditertiary phosphine complexes of ruthenium(0), and the preparation of new types of hydrido-complexes of ruthenium(II)

Abstract

Chatt and Davidson 843 154. The Tautornerism of Arene and Ditertiary Phosphine Complexes of Ruthenium(O), and the Preparation of New Types of Hydrido- complexes of Ruthenium(rr) .* By J. CHATT and J. M. DAVIDSON.The reduction of truns-[RuCl,(PP) ,] (PP = Me,PCH,CH,-PMe,) by " arene " negative ions (arene = benzene, naphthalene, anthracene, and phenanthrene) has given a new series of hydrido (aryl) -complexes typified by cis-[RuH(2-Cl0H,) (PP),] (Ia). Members have been characterised from their physical properties, particularly infrared and n.m.r. spectra, and their chemical reactions. Although (Ia) is a hydridic reducing agent and reduces bromoethane to ethane, it is in tautomeric equilibrium with a finite concentration of [Ru(C,,H,) (PP),] (Ib) which probably contains ruthenium(0) and is so reactive that its reactions predominate in those of the complex.Pyrolysis of (I) gives naphthalene and [Ru(PP),] (11) which has similarly dual properties. Its physical properties are consistent with the formulation

Living polymerization of α-amino acid-N-carboxyanhydrides

“…When these rhodium and iridium precursors were complexed with chelating bisphosphines (e.g., dmpe or depe), they reacted readily with NCAs and gave living polymerizations. 15 Successful controlled polymerizations were also found with the isoelectronic zerovalent iron and ruthenium complexes, (PMe 3 ) 4 Fe 22 and (dmpe) 2 Ru, 23 which also readily undergo two-electron oxidative-addition reactions. Preliminary studies on these complexes indicated that all metals react initially at the anhydride bond of the NCAs and not at the NOH position.…”

Organometallic C—H Bond Activation: An Introduction

“…Concomitant with Shilov's original work on electrophilic systems, observations from other laboratories seemed to point in an entirely opposite direction as the most promising route to C-H activation (8,42,43). Led by Chart's 1965 discovery of the reactions of the extremely electron-rich species Ru(dmpe) 2 (eq 5), several other examples were discovered in which apparently electron-rich metal centers were found capable of oxidatively adding C-H bonds.…”

“…However in 1983, Eisenberg discovered that Rh(PPh 3 ) 2 (CO)Cl photochemically catalyzed the carbonylation of benzene (94)(95)(96). As this reaction was assumed to proceed via photoextrusion of a ligand (either CO or PPh 3 ) the importance of three-coordinate d 8 fragments with respect to carbonylation was highlighted early. Accordingly, in fast timescale studies by Ford, C-H activation by Rh(PR 3 ) 2 Cl was observed directly (97).…”

“…Perhaps most significant, this report made explicit the importance of carboxylate dechelation, to yield a three-coordinate d 8 unit after transfer of the H atoms. Notably, virtually all other systems in this section are also based upon threecoordinate d 8 fragments, and in particular the ML 2 X unit where M = Rh or Ir and X is a halide or anionic group.…”

“…Jones has, however, developed several systems capable of catalyzing insertion to give aldimines (eq 24) (109,110) as well as intramolecular insertion to give indoles (111,112). These systems are based upon d 8 metal centers (Fe(0), Ru(0) and Rh(I)) bearing mono-and bidentate phosphines.…”