Reactions of Ruthenium Acetylide and Vinylidene Complexes Containing a 2-Pyridyl Group

Abstract

Two ruthenium acetylide complexes [Ru]CC(C5H3RN) (1a, R = H; 1b, R = Me; [Ru] = Cp(PPh3)2Ru) containing 2-pyridyl groups are prepared and their chemical reactivities are explored. Protonation of the ruthenium acetylide complex 1a with HBF4 takes place at both the nitrogen atom and Cβ, giving the dicationic pyridiniumvinylidene complex {[Ru]CC(H)(C5H4NH)}(BF4)2 (3a). Addition of BF3 to 1a yields the Lewis acid/base adduct [Ru]CC(C5H4N→BF3) (4a). In the presence of moisture both complexes 3a and 4a in solution transform into the cationic heterocyclic carbene complex {[Ru]C(O)CH2(C5H4N→BF2)}BF4 (6a), for which the structure is confirmed by X-ray structure determination. The formation of 6a involves the intermediate {[Ru]CC(H)(C5H4N→BF2OH)}BF4 (5a), characterized by spectroscopic methods. DFT calculations show that the Gibbs free energy change of the exothermic transformation of 5a to 6a is −20.59 kcal/mol. N-Alkylation reactions of 1b with two alkyl bromides BrCH2R′ (R′ = CHCHCO2Me and CO2Me) yield two pyridiniumacetylide complexes {[Ru]CC(C5H3MeNCH2R′)}Br (7b, R′ = CHCHCO2Me; 7c, R′ = CO2Me, respectively). Complex 7c, characterized by X-ray structure determination, undergoes further protonation to give the pyridiniumvinylidene complex {[Ru]CC(H)(C5H4NCH2R′)2+ (8c). Interestingly, the acetylide complex 7b undergoes a C−C coupling reaction of the acetylic Cβ with the CC double bond to give the vinylidene complex 9b, characterized also by X-ray structure determination.

Cyclization Reactions of Aryl Propargyl Acetates with Tethered Epoxide Induced by Ruthenium Complex

“…The vinylidene ligand is bound to the ruthenium in a nearly linear fashion with a Ru‐C(1)‐C(2) angle of 170.6(3)°. The Ru−C(1) (1.857(3) Å) and C(1)−C(2) (1.311(5) Å) bond lengths compare well with those found in other ruthenium‐vinylidene complexes and support the vinylidene formulation ,. Opening of the epoxide ring followed by a C−C bond formation with addition of an OMe group at C(3) leads to the seven‐membered ring.…”

“…In the 2D‐HMBC NMR spectrum of the major isomer of 5 a , the triplet peak at δ 349.08 with 2 J cp =15.1 Hz, assigned to Cα, shows correlations with the 1 H resonances at δ 4.72, 2.85 and 2.52 assigned to the CγH and the nearby methylene group, respectively. The multiplet peak at δ 3.76, assigned to C H (OH), shows correlation with the 13 C resonance at δ 124.22 assigned to Cβ ,. The 2D‐HMBC NMR spectrum of 5 b also displays similar correlations.…”

Crystal structure of μ-carbonyl-1:2κ2C:C-carbonyl-1κC-(1η5-cyclopentadienyl)iodido-2κI-[μ-2-(pyridin-2-yl)ethene-1,1-diyl-1κC1:2κ2N,C1]ironpalladium(Fe—Pd) benzene monosolvate

“…Transition metal -pyridylethynyl complexes attract considerable research interest since they can act as precursors for pyridylvinylidene complexes (Chou et al, 2008) and as buildings blocks for supramolecular assemblies in molecular electronics (Le Stang et al, 1999), as well as materials for nonlinear optics (Wu et al, 1997).…”

Catalyzed M–C coupling reactions in the synthesis of σ-(pyridylethynyl)dicarbonylcyclopentadienyliron complexes

“…Metal s-alkynyl complexes displaying such peculiar characteristics as linear geometry, high stability, and p-unsaturated character have been demonstrated to constitute promising building blocks for the design of materials, which can possess such properties as optical nonlinearity, [1][2][3][4][5] light-emission, [6][7][8][9][10][11][12] and electrical conductivity. [13][14][15][16][17][18] Moreover, they are an important class of coordination compounds because of their relevance in synthetic chemistry [19][20][21][22][23][24] and proton reduction catalysis. [25][26][27] A variety of methods for the synthesis of transition metal acetylides have been developed.…”