Nucleophilic Addition Reactions to Allenylidene Complexes of Ruthenium Bearing Hemilabile P,N Ligands: Isolation of the Vinylcarbene Complex [Cp*Ru═CHCH═CPh₂(ⁱPr₂PNHPy)][PF₆]

Abstract

The complex [Cp*RudCdCdCPh 2 ( i Pr 2 PNHPy)][PF 6 ] (2), prepared by reaction of [Cp*Ru(MeCN)-( i Pr 2 PNHPy)][PF 6 ] (1) with HCtCC(OH)Ph 2 , reacts with primary amines, furnishing the corresponding vinylaminocarbenes, which are better formulated as the azoniabutadienyl derivatives [Cp*Ru{C(NHR)-CHdCPh 2 }( i Pr 2 PNHPy)][PF 6 ] (R = Cy (6a), Me (6b), CH 2 CtCH (6c)). These species result from the nucleophilic attack of the amine at the C R atom of the allenylidene ligand. At variance with this, the reaction of 2 with cyclic secondary amines such as piperidine, pyrrolidine, and morpholine yields the Schrock-type vinylcarbene complex [Cp*RudCHCHdCPh 2 ( i Pr 2 PNHPy)][PF 6 ] (7), which has been unequivocally characterized by X-ray structure analysis. This vinylcarbene complex is presumably formed by addition of the cyclic amine to the C γ atom of the allenylidene through the intermediacy of a vinylidene complex. This intermediate vinylidene undergoes a retro-metallo-ene rearrangement, generating 7 plus the product of dehydrogenation of the amine. The reaction of 2 with thiophenol or pentafluorothiophenol afforded the thiocarbenes [Cp*Ru{C(SC 6 R 5 )CHdCPh 2 }( i Pr 2 PNHPy)][PF 6 ] (R = H (8H), F (8F)), which have been structurally characterized. Alternatively, the reaction of 2 with pyridine-2-thiol or pyrimidine-2-thiol leads to the thiocarbenes [Cp*). In these compounds a new five-membered chelate ring has formed, and the i Pr 2 NHPy ligand exhibits hemilabile character, changing its coordination mode from κ 2 P,N to κ 1 P.

A Half Sandwich Ruthenium(II) Complex with N‐4,6‐Dimethyl‐2‐pyrimidinylimidazole: Synthesis, Crystal Structure and Application in N‐Alkylation of Amines with Alcohols

“…The complex has an essentially octahedral coordination geometry comprising the p ‐cymene ring carbons occupying one face of the octahedron leaving the other three sites to be coordinated by two chloride atoms and monodentate ( N ‐4,6‐dimethyl‐2‐pyrimidinylimidazole) ligand. The RuN bond length 2.113(3) Å of 1 is similar to those of the related arene Ru(II) complexes . The imidazole ring and the pyrimidine ring are approximately coplanar (dihedral angle of 9.0°).…”

Counteranion and Solvent Assistance in Ruthenium-Mediated Alkyne to Vinylidene Isomerizations

“…We carried out ionic conductivity (Λ) measurements for complexes 2a/b-Cl and 2a/b-BPh 4 in nitromethane solution (Table 1) We can explain these data by considering a strong hydrogen bonding interaction between the chloride and the NH group of the i Pr 2 PNHPy ligand, which leads to formation of a tight ion pair ( Figure 1A). However, taking into account the potential hemilabile character of the i Pr 2 PNHPy ligand, 29,32 we might also have a situation in which the chloride displaces the pyridyl group, furnishing a neutral chlorovinylidene complex bearing a monodentate κ 1 -P-i Pr 2 PNHPy ligand, with an intramolecular hydrogen bonding interaction between the NH and the chloride ( Figure 1B).…”

A New Class of Redox Isomerization of N-Alkylpropargylamines into N-Alkylideneallylamines Catalyzed by a ReBr(CO)5/Amine N-oxide System

“…Detailed experimental procedures; characterization data of all of the new compounds; 1 H and 13 C NMR spectra of the products; copies of HPLC chromatograms (PDF)…”