Syntheses of Nonracemic Ortho-Mercurated and Ortho-Ruthenated Complexes of 2-[Tricarbonyl(η⁶-phenyl)chromium]pyridine

Abstract

The reaction of racemic orthomercurated (η6-arene)tricarbonylchromium complexes with bis[(?6-cymene)ruthenium(II)dichloride] affords the corresponding dinuclear (Cr,Ru) products with moderate yields, which have been satisfactorily characterized by X-ray diffraction analysis. The synthesis of nonracemic orthomercurated (η6-arene)tricarbonylchromium complexes has been attempted starting from enantio-enriched homo- and heteroleptic Pd(II) bischelated complexes. Both enantiomers of ortho-mercurated 2-[tricarbonyl(?6-phenyl)chromium]pyridine have been synthesized by reaction of a heteroleptic Pd(II) bischelated with HgCl2. The two mercury(II) complexes were also submitted to a transmetalation reaction with bis[(?6-cymene)ruthenium(II)dichloride] and yielded the corresponding nonracemic (Cr, Ru) products, with enantiomeric excesses ranging from 82 to 89% as suggested by 1H NMR analyses in the presence of BINPHAT anion

Enantiopure Ferrocene‐Based Planar‐Chiral Iridacycles: Stereospecific Control of Iridium‐Centred Chirality

“…It is of note that the relative stereochemistry of all known (racemic) chromium tricarbonyl η 6 ‐arene‐based metallacycles containing IrCp* (e.g., 23 ) or RhCp* (e.g., 24 ) are also exclusively R p *, S Ir * (Figure ), and that, in the iridium series, stereospecific substitution has been established through the dissociative formation of a chromium‐stabilised cationic intermediate . Complexes 23 and 24 were synthesised from [Cp*MCl 2 ] 2 by C−H activation with sodium acetate.…”

Halide Control of N,N-Coordination versus N,C-Cyclometalation and Stereospecific Phenyl Ring Deuteration of Osmium(II) p-Cymene Phenylazobenzothiazole Complexes

“…Older synthetic routes utilize a transmetalation pathway involving ortho-mercurated species, eliminating the need for C–H activation. 29 − 32 However, direct metalation of 2-phenylpyridine (2-PhPy) is also possible in the presence of bases such as acetate and is directed by the nitrogen-containing pyridine moiety, which initially binds to the metal center. In the reaction between [Os(η 6 - p -cym)X 2 ] 2 and L , the direction may be guided via initial coordination to the azo bond nitrogen, and C–H activation occurs spontaneously and remarkably in the absence of an additional base.…”

Driving the Morita–Baylis–Hillman Reaction to a Multicomponent Organic Transformation

“…The Ru–N pyridine bond length was shorter than the Ru–N triazine bond, thus indicating that the pyridine N donor atom is a stronger σ donor. The Ru–C σ‐bond length in complex 3.H2O was in the usual range37 and the Ru–N triazine bond was similar in length to that of complex 2.BF4 . The triazine rings were not completely planar in either complex 2.BF4 or complex 3.H2O and the amine groups adopted trigonal planar geometries with short C–NH 2 distances that were consistent with intermediate bonding between single and double bonds.…”