Catalysis of phenyl isocyanate condensation to N,N'-diphenylcarbodiimide via vanadium oxo and imido complexes

Birdwhistell, K. R.; Boucher, T.; Ensminger, Mike; Harris, S.; Johnson, Mike; Toporek, Stan S.

doi:10.1021/om00028a015

Cited by 69 publications

(37 citation statements)

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“…43 Transition metal imido complexes are well known as potential reagents for N-C bond formation reactions. [44][45][46] During the study of the reaction of [PcTiO] 1 with excess arylisocyanates we found that upon six days of heating, a steady evolution of CO 2 and formation of a white precipitate of diarylcarbodiimides (RN C NR) occurs. We therefore investigated the catalytic properties of 1 in the formation of carbodiimides.…”

Section: [Pctio] Catalyzed Synthesis Of Carbodiimidesmentioning

confidence: 99%

Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(iv) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

et al. 2011

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The imido titanium phthalocyanine complex [PcTi(NDip)] (Dip = 2,6-diisopropylphenyl) 2a was synthesized from [PcTiO] 1 and one eq. of DipNCO. Due to the steric demand of the Dip group, addition of another isocyanate molecule to the Ti = N functionality of 2a does not occur even at high molar ratios of DipNCO. However, 1 reacts with 2 eq. of arylisocyanates containing sterically less demanding aryl groups producing N,N'-diarylureatotitanium(iv)phthalocyanines [PcTi{κ(2)-(NR)C(O)(N'R)}] (R = p-tolyl (Tol) 3a or mesityl (Mes) 3b). The N,N' coordination (III) of the ureato ligand in 3a and 3b was proven by a single set of resonances for the aryl groups in their (1)H-NMR spectra. An N,O coordination (IV) can therefore be excluded. This is also confirmed by the X-ray crystal structure of 3a. Upon heating [PcTiO] and an excess of aryl isocyanates for 6 days, a steady evolution of CO(2) was observed and a white precipitate, identified as the corresponding diarylcarbodiimides (V), could be isolated. Therefore this reaction was applied in the metathetic conversion of two isocyanate molecules into diarylcarbodiimides (V) and CO(2). Additionally, imido titanium Pc's 2b (R = tBu) and 2c (R = Mes) were prepared by a more general synthetic strategy, reacting the potassium salt of the ligand PcK(2) with appropriate imido titanium precursors.

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Section: [Pctio] Catalyzed Synthesis Of Carbodiimidesmentioning

confidence: 99%

Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(iv) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

et al. 2011

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“…No reaction was observed when the starting complex 1a was added to a solution containing the tantalum(III) complex. Carbodiimides have also been synthesized by coupling isocyanates with elimination of CO 2 , using phosphine oxides [18] and imido vanadium [10] or tungsten [6a] compounds as catalysts.…”

Section: Synthesis Of Imido Complexesmentioning

confidence: 99%

“…Imido titanium [7] and zirconium [5c,8] complexes have been shown to activate the carbon-hydrogen bond of hydrocarbons. Fewer studies have been reported for [2+ 2] cycloaddition or carbon-hydrogen bond activation reactions of imido vanadium [9] [10] and tantalum [11] complexes. We reported [12] several reactions giving imido tantalum complexes and the conversion of an imido acyl complex into the oxo iminoacyl derivative.…”

Section: Introductionmentioning

confidence: 99%

Oxo and imido/imido exchange and C–H activation reactions based on pentamethylcylopentadienyl imido tantalum complexes

Royo

Sánchez‐Nieves

2000

Journal of Organometallic Chemistry

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“…Building on these reports, Birdwhistell and co-workers have developed a variety of vanadium oxo and imido complexes that catalyzed the metathesis of carbodiimides ( Table 3) [109]. These complexes also mediate the condensation of aryl isocyanates to N,N'-diarylcarbodiimides ( Table 2) [110]. Unfortunately, high temperatures and low yields are drawbacks of this synthetic methodology.…”

Section: B Metathesis Reactionsmentioning

confidence: 99%

Transition Metal Catalyzed Reactions of Carbon Dioxide and Other Heterocumulenes

Louie¹

2005

COC

179

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Catalysis of phenyl isocyanate condensation to N,N'-diphenylcarbodiimide via vanadium oxo and imido complexes

Cited by 69 publications

References 0 publications

Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(iv) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(iv) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

Oxo and imido/imido exchange and C–H activation reactions based on pentamethylcylopentadienyl imido tantalum complexes

Transition Metal Catalyzed Reactions of Carbon Dioxide and Other Heterocumulenes

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