Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Abstract

The allenylidene complex [Ru(η5-C5H5)(CCCPh2)(CO)(PPri 3)]BF4 (1) reacts with dicyclohexylcarbodiimide to give the iminiumazetidinylidenemethyl complex (2), as a 4:1 mixture of isomers Z (2a) and E (2b). The structure of 2a was determined by an X-ray investigation, revealing a Ru−C distance of 2.070(4) Å. Treatment of the isomeric mixture of 2 with sodium methoxide in tetrahydrofuran at room temperature affords the iminoazetidinylidenemethyl complex (6), which reacts with HBF4·OEt2 to give (7), as a result of the protonation of the exocyclic nitrogen atom of the unsaturated η1-carbon ligand of 6. In the solid state and in solution at low temperature, complex 7 is stable. However, in solution at room temperature, complex 7 evolves into (8), which reacts with sodium methoxide in tetrahydrofuran at room temperature to give the hexahydroquinolinylidenemethyl complex (9), as a result of the deprotonation of the endocyclic nitrogen atom of 8. The structure of 9 was also determined by an X-ray investigation, revealing, in this case, a Ru−C distance of 2.113(4) Å. The formation of the azetidine and hexahydroquinoline skeletons of the ligands of these compounds is discussed.

C–H Activation via Carbodiimide Insertion into Yttrium–Carbon Alkynide Bonds: An Organometallic Alder-ene Reaction

“…Instead, absorptions at 1677 and 1509 cm –1 for 4 and at 1670 and 1514 cm –1 for 5 are observed and assigned to ν(CN) and ν(CC), respectively. These values are close to those observed in the cyclic iminiumazetidinylidenemethyl complex [(C 5 H 5 )Ru{CHCCPh 2 N(Cy)CNC(CH 2 ) 4 CH 2 }(CO)(P i Pr 3 )][BF 4 ], which has similar functionality [ν(CN) 1679 cm –1 and ν(CC) 1528 cm –1 ] (Figure ).…”

Recent Developments in the Reactivity of Allenylidene and Cumulenylidene Complexes

“…Cationic transition metal allenylidene complexes are useful starting materials to generate unsaturated cyclic structures by the reaction of their highly polarized unsaturated chain with organic substrates 4a−4b. In this context, Esteruelas and co‐workers have recently reported63 that [Ru(=C=C=CPh 2 )(η 5 ‐C 5 H 5 )(CO)(P i Pr 3 )][BF 4 ] reacted with dicyclohexylcarbodiimide to afford the unprecedented iminium azetidinylidenemethyl complex 48 which was isolated as a mixture of the corresponding ( Z ) ( 48a ) and ( E ) ( 48b ) stereoisomers (Scheme ). Formation of 48 can be rationalized as the result of a [2+2] cycloaddition between the C β −C γ double bond of the allenylidene ligand and one of the two carbon−nitrogen double bonds of the carbodiimide group.…”

Pyrrolyl substituted allenylidene complexes of ruthenium

“…Assignment of the I.1C NMR peaks of compound 2c was perform ed according to the litera ture data lo r 1 ,3-dimethylindole. 7S tl'alls-( CI( dpplll) ,R u = C = C = C {I-Illcthyla lllinop yrro l-2-yl)(CH3W B{C 6 H 3 (CF 3 ),-3,S}.-(2a·BArF) and thc SbF.-salt 2a·SbF 6 • The crude product ob tained fro 111 235 111g of ci.\·-[RuCI 2 (dppm)2) (0.25 11111101), 222 I11g of Na-tetrakis(3,5-trifluoromethyl)tetraphenylborate (NaBAr", 0.25 11111101) a nd 44 ~t1 of N-l11e thylpyrro le (0.500 111111 01) in THF as solve nt was dissolved in 3 1111 of CH 2 Cl 2 and layered with I 1111 of n-hexa ne. The SbF 6 -salt was obtain ed in 76% yield from a like reaction in v-dichlorobenzene as the solvent.…”

“…Spectroscopic data: 1 H NMR (250.13 MHz, CD 2 Cl 2 ): d 1.33 (s, 3H, C-CH 3 ), 2.55 (s, 3H, NCH 3 ), 5.05 (dqnt, J HH = 15.4 Hz, 2 J PH = 4 J PH = 4.0 Hz, 2H, CH 2 (dppm)), 5.36 (dqnt, J HH = 15.4 Hz, 2 J PH = 4 J PH = 5.1 Hz, 2 H, CH 2 (dppm)), 6.10 (dd, 3 J HH = 4.0, 2.85 Hz, 1H, H 4 (pyrrole)), 6.92 (m. 2H, H 3,5 (pyrrole)), 7.21 (t, 3 J HH = 7.8 Hz, 8 H, CH (dppm)), 7.32 (m, 16 H, CH (dppm)), 7.41 (t, 3 J HH = 7.1 Hz, 4 H, CH (dppm)), 7.42 (t, 3 J HH = 7.2 Hz, 4 H, CH (dppm)), 7.52 (m, 8 H, CH (dppm)), 7.62 (s, 4 H, CH 4 (BAr F − ), 7.81 (m, 8H, CH 2,5 (BAr F − ). 13 C NMR (62.896 MHz, CD 2 Cl 2 ) d 30.7 (s, C-CH 3 ), 35.6 (s, NCH 3 ), 46.9 (vqnt, J PC = 11.3 Hz, CH 2 (dppm)), 111.9, (s, CH (pyrrole)), 117.6 (hept, 3 J CF = 1.54 Hz, C 4 (BAr F − )), 124.8 (q, J CF = 272 Hz, CF 3 (BAr F − )), 125.3 (s, CH (pyrrole)), 128.3 (vqnt, J PC = 2.6 Hz, CH meta (dppm)), 128.8 (vqnt, J PC = 2.6 Hz, CH meta (dppm)), 129.1 (q of non-binomial q, 2 J CF = 31.7 Hz, 2 J BC = 3.05 Hz, C(CF 3 ) (BAr F − )), 130.6 and 131.1 (s, CH para (dppm)), 131.89 (vqnt, J PC = 12.5 Hz, CH ipso (dppm)), 132.9 and 133.2 (vqnt, J PC = 3.05 Hz, CH ortho (dppm)), 133.0 (vqnt, J PC = 11.3 Hz, CH ipso (dppm)), 135.0 (m, C 2,6 (BAr F − )), 138.0 (s, CH (pyrrole)), 139.8 (s, C 2 (pyrrole)), 149.2 (qnt, 4 J PC = 1.22 Hz, C c ), 162.9 (non-binomial q, J BC = 50.1 Hz, C 1 (BAr F − )), 169.7 (qnt, 3 J PC = 2.14 Hz, C b ), 270.8 (qnt, 2 J PC = 13.1 Hz, C a ). 31 The SbF 6 − salt was obtained in 76% yield from a like reaction in o-dichlorobenzene as the solvent.…”

“…Allenylidene (or propadienylidene) complexes are characterized by a cumulated C 3 R 2 ligand which is attached to a metal atom via a formal metal-carbon double bond. These systems have meanwhile evolved from mere laboratory curiosities into valuable building blocks for advanced syntheses [1][2][3][4][5][6][7][8][9][10][11][12][13] and powerful catalysts for olefin metathesis. [14][15][16][17][18][19][20][21] This is especially true for monocationic ruthenium derivatives.…”