Metathesis and diaziridination reactions of (CO)5W=C(OMe)-p-XC6H4 with cis-azobenzene. Electronic and solvent effects

Maxey, Claudia Tata; Sleiman, Hanadi F.; Massey, Scott T.; McElwee‐White, Lisa

doi:10.1021/ja00039a029

Cited by 28 publications

(8 citation statements)

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“…In a similar way, chemical reduction of the (1-pyridinio)imido complexes cis , trans -[WCl 2 (NNC 5 H 5 - n R n )(PMe 2 Ph) 2 (L)] (R = alkyl; L = CO, C 2 H 2 ) in the presence of proton source is known to yield smoothly the imido complexes cis , trans -[WCl 2 (NH)(PMe 2 Ph) 2 (L)] and pyridines NC 5 H 5 - n R n . With respect to the formation of the organoimido ligand via cleavage of the N−N bond on the single metal center, it has been reported that decomposition or halogenation of [(CO) 5 W{NPhNPhC(OMe)Me}] gives [(CO) 5 W(NPh)] or [(CO) 2 W(NPh)X 2 ] 2 , respectively, together with PhNC(OMe)Me. Disproportionation of two RCONHNHR‘ into a NR‘ and a R‘NNCOR ligand on Mo(IV) complexes has also been precedented …”

Section: Resultsmentioning

confidence: 92%

N−N Bond Cleavage of Organohydrazines by Molybdenum(II) and Tungsten(II) Complexes Containing a Linear Tetraphosphine Ligand. Formation of Nitrido or Imido Complexes and Their Reactivities

et al. 2007

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The Mo(II) tetraphosphine−dihalide complexes [MoX2(κ4-P 4)] (X = Cl (2a), Br (2b); P 4 = meso-o-C6H4(PPhCH2CH2PPh2)2) having uncommon trigonal-prismatic geometry cleaved the N−N bond in Me2NNH2 and PhNHNH2 at room temperature to form the nitrido complexes trans-[MoX(N)(κ4-P 4)] (X = Cl (3a), Br (3b)). In contrast, similar reactions of the W(II) congener [WBr2(κ4-P 4)] afforded the imido complex trans-[WBr(NH)(κ4-P 4)]+ (4c + ), which was isolated as a PF6 or BPh4 salt. Addition of HBF4 converted 3 into the imido complexes trans-[MoX(NH)(κ4-P 4)][BF4] (X = Cl (4a[BF4]), Br (4b[BF4])), while deprotonation of 4a + and 4b + by NEt3 readily regenerated 3a and 3b. At elevated temperatures, 2a also reacted with RNHNHR (R = Me, Ph), giving the corresponding organoimido complexes trans-[MoCl(NR)(κ4-P 4)][PF6] (6[PF6]) after anion metathesis with K[PF6]. The mechanism has been proposed for the N−N bond cleavage, which involves the proton shift in the end-on coordinated organohydrazine followed by the two-electron reduction by the M(II) center to give the M(IV) imido complex and the amine. The nitrido ligand in 3a is susceptible to electrophilic attack by methyl trifluoromethanesulfonate to form 6[CF3SO3] (R = Me), while reactions of 3a with acid chlorides RCOCl (R = Me, Ph, p-tolyl (Tol)) afforded the neutral acylimido complexes cis,mer-[MoCl2(NCOR)(κ3-P 4)] (7). Treatment of 7 with K[PF6] yielded the cationic complexes trans-[MoCl(NCOR)(κ4-P 4)][PF6] (8[PF6]). On the other hand, imido complex 4a[BF4] smoothly reacted with isocyanates RNCO (R = Ph, Tol) in the presence of a catalytic amount of Et3N to give the carbamoylimido complexes trans-[MoCl(NCONHR)(κ4-P 4)][BF4] (9[BF4]), and the thiocarbamoyl analogue trans-[MoCl(NCSNHPh)(κ4-P 4)][PF6] (10[PF6]) was also obtained from 4a[PF6] and PhNCS. Although hydrolysis of 7 (R = Tol) in a THF/aqueous KOH mixture resulted in the formation of p-toluamide only in low yield, reduction of the same complex with NaBH4 and LiAlH4 generated p-toluamide and 4-methylbenzylamine, respectively, in moderate yields. Molecular structures of 3a, 4a[BF4], 4c[BPh4], 6[PF6] (R = Me), 6[BF4] (R = Ph), 7 (R = Me), 8[PF6] (R = Me), and 9[BF4] (R = Tol) were determined crystallographically.

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Section: Resultsmentioning

confidence: 92%

N−N Bond Cleavage of Organohydrazines by Molybdenum(II) and Tungsten(II) Complexes Containing a Linear Tetraphosphine Ligand. Formation of Nitrido or Imido Complexes and Their Reactivities

et al. 2007

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“…In contrast, the primary reaction step in the photochemical reactions of tungsten carbene complexes [(CO) 5 WC(XR)R‘] seems to be the photoinduced loss of a CO ligand. , Subsequent addition of nucleophiles to the resulting coordinatively unsaturated species affords substitution products c i s -[(CO) 4 (L)WC(XR)R‘] (L = PR 3 , MeCN, THF, or alkynes 8 ). The quantum yield of CO loss from [(CO) 5 WC(XR)R‘] is fairly low (approximately 1% at 366 and 313 nm) and drops to less than 10 -4 at 436 nm. , This has been explained by the inactivity in photodissociation of the long-wavelength metal-to-ligand charge transfer (MLCT) transition and by the only small activity of the ligand-field (LF) excitation due to its rapid radiationless decay to the lower MLCT state.…”

Section: Introductionmentioning

confidence: 99%

Formation and Reactions of Tetracarbonyl Intermediates of the Fischer Carbene Complex (CO)₅WC(OMe)Ph. A Laser Flash Photolysis Study Using Time-Resolved Infrared and UV/Vis Spectroscopy

et al. 2000

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The results of nanosecond laser flash photolysis (XeCl excimer irradiation at 308 nm) of the Fischer carbene complex [(CO) 5 WdC(OMe)Ph] (C Z ) in di-n-butyl ether and n-hexane are reported. Spectrokinetical detection of the intermediates was based on transient absorptions simulaneously recorded in the UV/vis and the IR spectral regions. The primary photoproducts are the unstable isomer C E produced with a quantum yield of about 30% and a tetracarbonyl complex I-S, probably of structure [(CO) 4 (S)WdC(OMe)Ph], where S is a solvent molecule. The quantum yield of CO photoelimination was estimated as 1.7%. The C E isomer was found to return to the stable C Z isomer within a few microseconds, confirming previous results of McGarvey and co-workers. The tetracarbonyl species reacts with cosolutes present in the solution such as N 2 , H 2 O, acetonitrile, and methyl trans-crotonate to form secondary complexes of cis-tetracarbonyl complex structure [(CO) 4 (L)WdC(OMe)Ph] (I-L). The tetracarbonyl complexes react readily with CO. For I-N 2 in n-hexane the rate constant is 3.5 × 10 8 M -1 s -1 . The rate constants of the corresponding reactions with acetonitrile (MeCN) and the olefin are larger by a factor of 2. In the presence of CO the complexes I-MeCN and I-olefin revert to C Z in a dissociative reaction mechanism. The rate constants for the elimination of MeCN or olefin are 5 and 10 5 s -1 , respectively. The I-olefin complex irreversibly decomposes with a rate constant of 8 × 10 3 s -1 .

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“…21) [85,86]. Elegant mechanistic studies [87][88][89] indicated the primary photoprocess was trans-to-cis isomerization of the azoarene followed by subsequent thermal reaction with the carbene complex. Because of the low yields and mixtures obtained the process is of little synthetic use.…”

Section: With Azoarenes To Give Diazetidinonesmentioning

confidence: 99%

Photoinduced Reactions of Metal Carbenes in Organic Synthesis

Hegedus

2005

ChemInform

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Metathesis and diaziridination reactions of (CO)5W=C(OMe)-p-XC6H4 with cis-azobenzene. Electronic and solvent effects

Cited by 28 publications

References 1 publication

N−N Bond Cleavage of Organohydrazines by Molybdenum(II) and Tungsten(II) Complexes Containing a Linear Tetraphosphine Ligand. Formation of Nitrido or Imido Complexes and Their Reactivities

N−N Bond Cleavage of Organohydrazines by Molybdenum(II) and Tungsten(II) Complexes Containing a Linear Tetraphosphine Ligand. Formation of Nitrido or Imido Complexes and Their Reactivities

Formation and Reactions of Tetracarbonyl Intermediates of the Fischer Carbene Complex (CO)₅WC(OMe)Ph. A Laser Flash Photolysis Study Using Time-Resolved Infrared and UV/Vis Spectroscopy

Photoinduced Reactions of Metal Carbenes in Organic Synthesis

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Metathesis and diaziridination reactions of (CO)5W=C(OMe)-p-XC6H4 with cis-azobenzene. Electronic and solvent effects

Cited by 28 publications

References 1 publication

N−N Bond Cleavage of Organohydrazines by Molybdenum(II) and Tungsten(II) Complexes Containing a Linear Tetraphosphine Ligand. Formation of Nitrido or Imido Complexes and Their Reactivities

N−N Bond Cleavage of Organohydrazines by Molybdenum(II) and Tungsten(II) Complexes Containing a Linear Tetraphosphine Ligand. Formation of Nitrido or Imido Complexes and Their Reactivities

Formation and Reactions of Tetracarbonyl Intermediates of the Fischer Carbene Complex (CO)5WC(OMe)Ph. A Laser Flash Photolysis Study Using Time-Resolved Infrared and UV/Vis Spectroscopy

Photoinduced Reactions of Metal Carbenes in Organic Synthesis

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Formation and Reactions of Tetracarbonyl Intermediates of the Fischer Carbene Complex (CO)₅WC(OMe)Ph. A Laser Flash Photolysis Study Using Time-Resolved Infrared and UV/Vis Spectroscopy