Preparation and Structural Characterization of [CpRu(1,10‐phenanthroline)(CH₃CN)][X] and Precursor Complexes (X=PF₆, BAr_F, TRISPHAT‐N)

Abstract

Dedicated to Prof. Antonio Togni on the occasion of his 65th birthday Cationic [Ru(η 5-C 5 H 5)(CH 3 CN) 3 ] + complex, tris(acetonitrile)(cyclopentadienyl)ruthenium(II), gives rise to a very rich organometallic chemistry. Combined with diimine ligands, and 1,10-phenanthroline in particular, this system efficiently catalyzes diazo decomposition processes to generate metal-carbenes which undergo a series of original transformations in the presence of Lewis basic substrates. Herein, syntheses and characterizations of [CpRu(Phen)(L)] complexes with (large) lipophilic non-coordinating (PF 6 À and BAr F À) and coordinating TRISPHAT-N À anions are reported. Complex [CpRu(η 6-naphthalene)][BAr F ] ([1][BAr F ]) is readily accessible, in high yield, by direct counterion exchange between [1][PF 6 ] and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr F) salts. Ligand exchange of [1][BAr F ] in acetonitrile generated stable [Ru(η 5-C 5 H 5)(CH 3 CN) 3 ][BAr F ] ([2][BAr F ]) complex in high yield. Then, the desired [CpRu(Phen)(CH 3 CN)] ([3]) complexes were obtained from either the [1] or [2] complex in the presence of the 1,10-phenanthroline as ligand. For characterization and comparison purposes, the anionic hemilabile ligand TRISPHATÀ N (TTN) was introduced on the ruthenium center, from the complex [3][PF 6 ], to quantitatively generate the desired complex [CpRu(Phen)(TTN)] ([4]) by displacement of the remaining acetonitrile ligand and of the PF 6 À anion. Solid state structures of complexes [1][BAr F ], [2][BAr F ], [3][BAr F ], [3][PF 6 ] and [4] were determined by X-ray diffraction studies and are discussed herein.

Spirocyclic Amide Acetal Synthesis by [CpRu]‐Catalyzed Condensations of α‐Diazo‐β‐Ketoesters with γ‐Lactams

“…Using Rh 2 (OAc) 4 (1 mol‐%), [45] a yield of 37 % was obtained, while decomposition with [CpRu(MeCN)] 3 PF 6 (2.5 mol‐%) [46,47] led to a drastic improvement and a corresponding yield of 80 %. Selecting the [CpRu] complex for further experiments, the influence of the negative counterion was investigated, switching from PF 6 − to the large, lipophilic and less coordinating BAr F − anion [42] . To our satisfaction, the NMR yield improved to 90 % ( entry 5 ) validating the use of the bench‐stable [BAr F ] complex over its [PF 6 ] analogue.…”

“…Herein, in a new development, reactions of N ‐protected γ‐lactams 1 with α‐diazo‐β‐ketoesters 2 are reported ( Scheme 1, C ). Thanks to the combined use of [CpRu(CH 3 CN) 3 ][BAr F ] (Cp=C 5 H 5 , BAr F =tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate) and 1,10‐phenanthroline phen as diazo decomposition catalyst, [42] spiro amide acetals 3 are afforded (33–93 %). The reaction is compatible with traditional carbamate protecting groups and a variety of α‐diazo‐β‐ketoester reagents were used successfully.…”

Chemo‐ and Regioselective Multiple C(sp2)−H Insertions of Malonate Metal Carbenes for Late‐Stage Functionalizations of Azahelicenes

“…Using a reaction time of 3 h instead of 16 h, full conversion of 2 and a higher isolated yield of 3 a (69 %) were achieved (entry 10) [21] . Finally, salt [CpRu(CH 3 CN) 3 ][BAr F ] was tested (entry 11) [22] and a lower yield was observed (18 %) [23] . Of note, in term of reactivity, the formation of pyridinium ylide products was never observed despite the presence of the Lewis basic nitrogen atom [24] .…”

General Ir-Catalyzed N–H Insertions of Diazomalonates into Aliphatic and Aromatic Amines

“…Then, several solvents were tested with general success (see Supporting Information); dichloromethane (DCM) was selected for its practicality (entry 10). In our group, cationic [CpRu­(NCCH 3 ) 3 ] + (Cp = cyclopentadienyl) complexes are known to be also effective catalysts for the decomposition of acceptor–acceptor diazo reagents under mild conditions. , While an excellent result was obtained at 60 °C (99% NMR yield, entry 11), a slightly lower yield was observed at room temperature in DCM (91% NMR yield, entry 12). Considering the effectiveness of the reaction and the commercial availability of [Ir­(cod)­Cl] 2 , this complex was thus retained…”

“… 13 The method caught our attention for its mildness, 14 and we wondered how general the reaction could be in more classical solvent conditions and, importantly, with unhindered primary/secondary (heterocyclic) amines as substrates. Herein, we show that [Ir(cod)Cl] 2 (cod = 1,5-cyclooctadiene), but also [CpRu(NCCH 3 ) 3 ][BAr F ], 15 are effective catalysts in nonpolar solvents ( Scheme 1 ). The reactivities of both complexes are compared, and the commercial iridium dimer was overall preferred for its reactivity at room temperature and in the presence of a range of amines, including polyfunctional drugs such as Amoxapine, 16 Vortioxetine, 17 Pomalidomide, 18 or sensitive unsaturated diaza macrocycles.…”