“…Molecular views are shown in Figures −3, and selected bond parameters are listed in Tables −3. To our knowledge, no other organoruthenium imidic ester structure is known, and structurally characterized acylruthenium species are rare 1 Perspective view and atom-labeling scheme for 4 (Me). 2 Perspective view and atom-labeling scheme for 5 (H). 3 Perspective view and atom-labeling scheme for [ 6 (Me)] + .
Organometallics of type [Ru(C 6 H 2 O-2-CHNHC 6 H 4 R-3-Me-5)(PPh 3 ) 2 (CO)(Cl)], 3 (R ) H, Me, OMe, Cl), incorporating a four-membered C,O chelate ring smoothly react with CNBu t in benzene solution affording the yellow-colored organoruthenium imidic ester hydrochloride system [Ru(C 6 H 2 OCN(Bu t )HCl-2-CHNC 6 H 4 R-3-Me-5)(PPh 3 ) 2 (CO)(CNBu t )], 4, in which a fivemembered C,C chelate ring is present. While stable in the solid state, 4 is spontaneously reactive in solution, furnishing the red-colored chelate [Ru(C 6 H 2 (CO-1)O-2-CHNHC 6 H 4 R-3-Me-5)(PPh 3 ) 2 (CNBu t )(Cl)], 5, incorporating five-membered acyl-phenolato C,O chelation. Chloride elimination from 5 by excess CNBu t furnishes [Ru(C 6 H 2Characteristic spectral features of the families are reported. A notable electrochemical feature is that the Ru(III)/Ru(II) reduction potential increases with increasing number of carbon atoms in the coordination sphere: 5 < 6 + < 4. The X-ray structures of 4(Me), 5(H), and [6(Me)]Cl‚2CH 2 Cl 2 are reported. The equatorial coordination planes are RuC 4 , RuC 2 OCl, and RuC 3 O, respectively, the axis being uniformly defined by the trans RuP 2 fragment. Both 5(H) and 6(Me) + display iminium-phenolato N-H‚‚‚O hydrogen bonding, while in 4(Me), N-H‚‚‚Cl and C-H‚‚‚O hydrogen bondings are present. In the transformation 3 f 4, one CNBu t molecule displaces the chloride ligand and another inserts into the Ru-O bond, generating a chelated imidic ester function. In 4(Me) the Ru-CO bond (1.891(8) Å) lying trans to the imidic ester carbon is ∼0.1 Å longer than that in the precursor complex 3(Me). The Ru-C(aryl) distance is also longer in 4(Me) by 0.04 Å. Thus both the bonds are activated by isonitrile insertion and the transformation 4 f 5 occurs spontaneously with C-C bond formation via aryl migration attended with isonitrile elimination, the reaction following first-order kinetics. The activation parameters determined for the 4(Cl) f 5(Cl) reaction are ∆H q , 18.72(1.00) kcal mol -1 , and ∆S q , -17.89(3.20) eu, implying that the transition state is ordered but with an excess of net bond breaking over net bond formation. Logarithmic rate constants are found to vary linearly with the Hammett constant of the R substituent, consistent with nucleophilic aryl migration.
“…Molecular views are shown in Figures −3, and selected bond parameters are listed in Tables −3. To our knowledge, no other organoruthenium imidic ester structure is known, and structurally characterized acylruthenium species are rare 1 Perspective view and atom-labeling scheme for 4 (Me). 2 Perspective view and atom-labeling scheme for 5 (H). 3 Perspective view and atom-labeling scheme for [ 6 (Me)] + .
Organometallics of type [Ru(C 6 H 2 O-2-CHNHC 6 H 4 R-3-Me-5)(PPh 3 ) 2 (CO)(Cl)], 3 (R ) H, Me, OMe, Cl), incorporating a four-membered C,O chelate ring smoothly react with CNBu t in benzene solution affording the yellow-colored organoruthenium imidic ester hydrochloride system [Ru(C 6 H 2 OCN(Bu t )HCl-2-CHNC 6 H 4 R-3-Me-5)(PPh 3 ) 2 (CO)(CNBu t )], 4, in which a fivemembered C,C chelate ring is present. While stable in the solid state, 4 is spontaneously reactive in solution, furnishing the red-colored chelate [Ru(C 6 H 2 (CO-1)O-2-CHNHC 6 H 4 R-3-Me-5)(PPh 3 ) 2 (CNBu t )(Cl)], 5, incorporating five-membered acyl-phenolato C,O chelation. Chloride elimination from 5 by excess CNBu t furnishes [Ru(C 6 H 2Characteristic spectral features of the families are reported. A notable electrochemical feature is that the Ru(III)/Ru(II) reduction potential increases with increasing number of carbon atoms in the coordination sphere: 5 < 6 + < 4. The X-ray structures of 4(Me), 5(H), and [6(Me)]Cl‚2CH 2 Cl 2 are reported. The equatorial coordination planes are RuC 4 , RuC 2 OCl, and RuC 3 O, respectively, the axis being uniformly defined by the trans RuP 2 fragment. Both 5(H) and 6(Me) + display iminium-phenolato N-H‚‚‚O hydrogen bonding, while in 4(Me), N-H‚‚‚Cl and C-H‚‚‚O hydrogen bondings are present. In the transformation 3 f 4, one CNBu t molecule displaces the chloride ligand and another inserts into the Ru-O bond, generating a chelated imidic ester function. In 4(Me) the Ru-CO bond (1.891(8) Å) lying trans to the imidic ester carbon is ∼0.1 Å longer than that in the precursor complex 3(Me). The Ru-C(aryl) distance is also longer in 4(Me) by 0.04 Å. Thus both the bonds are activated by isonitrile insertion and the transformation 4 f 5 occurs spontaneously with C-C bond formation via aryl migration attended with isonitrile elimination, the reaction following first-order kinetics. The activation parameters determined for the 4(Cl) f 5(Cl) reaction are ∆H q , 18.72(1.00) kcal mol -1 , and ∆S q , -17.89(3.20) eu, implying that the transition state is ordered but with an excess of net bond breaking over net bond formation. Logarithmic rate constants are found to vary linearly with the Hammett constant of the R substituent, consistent with nucleophilic aryl migration.
“…Thus (2c) still contained a methyl and a carbonyl ligand, raising the possibility that it might react with more Me3CNC to form a diacetyl complex. If, however, complex (2c) also possessed structure (2), with R = Me in this instance, the remaining methyl and carbonyl ligands would be trans to one another, thus ruling out intramolecular combination to form a second acetyl ligand. When compound (2c) was treated with a further equimolar quantity of Me3CNC in CHC13 solution, a slow reaction did occur to respectively.…”
Section: Mecnc To Form [Ru(co)(cncm~)(cop~)p~(pm~~p~)~]~mentioning
confidence: 96%
“…It was also evident that the two PMe2Ph ligands were mutually trans.? In the reaction of [Ru(CO),Ph,(PMe,Ph),] with Me3CNC, the isonitrile enters trans to the newly formed acyl ligand; assuming that the stereochemistry of the reaction of complex (la) with Me3CNC was similar to this, we assigned structure (2) n.m.r. data are listed in Table 2.…”
Section: Mecnc To Form [Ru(co)(cncm~)(cop~)p~(pm~~p~)~]~mentioning
Methyl complexes (Ru(CO),MeR(PMe,Ph),] ((la), R = Ph; ( l b ) , R = COMe; ( l c ) , R = Me] react with Me,CNC to form acetyl complexes [ Ru (CO) (CN CMe,) (CO Me) R ( PMe, Ph) J, (2a)-( 2c).
“…Acylruthenium organometallics bearing a pendant aldehyde group is unprecedented. Another point of interest is that very few structurally characterized acylruthenium organometallics are documented in the literature [9].…”
By reacting [Ru(RL 1 )(PPh 3 ) 2 (CO)Cl], (1) (R = C 6 H 4 Me, Et ) with an excess of CNBu t in the presence of NH 4 PF 6 , organometallics of the type [Ru(RL 2 )(PPh 3 ) 2 (CNBu t ) 2 ]PF 6 , (2) have been isolated in excellent yield [RL 1 = C 6 H 2 O-2-CHNHR(p)-3-Me-5, RL 2 = C 6 H 2 (CO)-O-2-CHNHR(p)-3-Me-5]. These organometallics, on controlled hydrolysis, produce [Ru(L 3 )(PPh 3 ) 2 (CNBu t ) 2 ], (3) in very good yield (L 3 = C 6 H 2 (CO)-O-CHO-3-Me-5). In both ([2(C 6 H 4 Me)] AE 2H 2 O) and ([3] AE 2CH 2 Cl 2 ) the two phosphine ligands lie in trans positions. In ([2(C 6 H 4 Me)] AE 2-H 2 O) the Ru(C 6 H 4 MeL 2 ) fragment, excluding the pendant tolyl ring, is a near perfect plane (mean dev$ 0.02Å ) which makes a dihedral angle of 5.2°with the tolyl plane. The acyl chelate ring in ([2(C 6 H 4 Me)] AE 2H 2 O) is excellently planar with a mean deviation of 0.006°. In ([3] AE 2CH 2 Cl 2 ) the Ru(L 3 ) fragment defines a crystallographic plane of symmetry, the coordinates of the atom being of the type x, 1/4z. The complex ([2(C 6 H 4 Me)] AE 2H 2 O) displays NAHÁ Á ÁO (iminium-phenolato) hydrogen bonding while in ([3] AE 2CH 2 Cl 2 ) CAHÁ Á ÁO hydrogen bonding is present. Characteristic spectral data (u.v.-vis, i.r. and 1 H n.m.r.) of the complexes are reported. A notable feature is that an allowed band near 500 nm due to the t 2g fi p * (azomethine) charge transfer transition, which is diagnostic of the coordinated iminium-phenolato function, is present in (3) but this band is absent in the aldehydic acyl complex (2). In the 1 H n.m.r. spectrum the N + -H signal in (2) (near 13.5 ppm) is split into a doublet due to trans coupling with the azomethine proton. The aldehydic proton of (3) resonates as a sharp singlet near 10 ppm. In CH 2 Cl 2 solution (2) and (3) display quasireversible a Ru III /Ru II cyclic voltammetric response with E 1/2 near 0.9 and 0.5 V versus s.c.e. The conversion (2) fi (3) is accompanied by the nucleophilic attack of water. The complex (3) is also obtained directly from (1) by reaction with CNBu t in the presence of H 2 O. The aldehyde function in (3) is deactivated by the existing acyl moiety; as a result further decarbonylation does not take place.
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