skip to main content


Title: Phosphorus‐Atom Transfer from Phosphaethynolate to an Alkylidyne
Abstract

A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡CtBu) (2) (Menacnac=[ArNC(CH3)]2CH, Ar=2,6‐iPr2C6H3), was prepared upon treatment of the vanadium neopentylidyne complex (Menacnac)V≡CtBu(OTf) (1) with Na(OCP)(diox)2.5(diox=1,4‐dioxane), while the isoelectronic ate‐complex [Na(15‐crown‐5)]{([ArNC(CH2)]CH[C(CH3)NAr])V(CO)(η2‐P≡CtBu)} (4), was obtained via the reaction of Na(OCP)(diox)2.5and ([ArNC(CH2)]CH[C(CH3)NAr])V≡CtBu(OEt2) (3) in the presence of crown‐ether. Computational studies suggest that the P‐atom transfer proceeds by [2+2]‐cycloaddition of the P≡C bond across the V≡CtBu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes,2and4, was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X‐ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X‐ray single‐crystal structural characterization. In combination, these data are consistent with a low‐valent vanadium ion in complexes2and4. This study represents the first example of a metathesis reaction between the P‐atom of [PCO]and an alkylidyne ligand.

 
more » « less
NSF-PAR ID:
10303976
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie
Volume:
133
Issue:
46
ISSN:
0044-8249
Page Range / eLocation ID:
p. 24616-24622
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡CtBu) (2) (Menacnac=[ArNC(CH3)]2CH, Ar=2,6‐iPr2C6H3), was prepared upon treatment of the vanadium neopentylidyne complex (Menacnac)V≡CtBu(OTf) (1) with Na(OCP)(diox)2.5(diox=1,4‐dioxane), while the isoelectronic ate‐complex [Na(15‐crown‐5)]{([ArNC(CH2)]CH[C(CH3)NAr])V(CO)(η2‐P≡CtBu)} (4), was obtained via the reaction of Na(OCP)(diox)2.5and ([ArNC(CH2)]CH[C(CH3)NAr])V≡CtBu(OEt2) (3) in the presence of crown‐ether. Computational studies suggest that the P‐atom transfer proceeds by [2+2]‐cycloaddition of the P≡C bond across the V≡CtBu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes,2and4, was further investigated both theoretically and experimentally, using a combination of density functional theory (DFT) calculations, UV/Vis and NMR spectroscopies, cyclic voltammetry, X‐ray absorption spectroscopy (XAS) measurements, and comparison of salient bond metrics derived from X‐ray single‐crystal structural characterization. In combination, these data are consistent with a low‐valent vanadium ion in complexes2and4. This study represents the first example of a metathesis reaction between the P‐atom of [PCO]and an alkylidyne ligand.

     
    more » « less
  2. Abstract

    Decarbonylation along with E atom transfer from Na(OCE) (E=P, As) to an isocyanide coordinated to the tetrahedral TiIIcomplex [(TptBu,Me)TiCl], yielded the [(TptBu,Me)Ti(η3‐ECNAd)] species (Ad=1‐adamantyl, TptBu,Me−=hydrotris(3‐tert‐butyl‐5‐methylpyrazol‐1‐yl)borate). In the case of E=P, the cyanophosphide ligand displays nucleophilic reactivity toward Al(CH3)3; moreover, its bent geometry hints to a reduced Ad−NCP3−resonance contributor. The analogous and rarer mono‐substituted cyanoarsenide ligand, Ad−NCAs3−, shows the same unprecedented coordination mode but with shortening of the N=C bond. As opposed to TiII, VIIfails to promote P atom transfer to AdNC, yielding instead [(TptBu,Me)V(OCP)(CNAd)]. Theoretical studies revealed the rare ECNAd moieties to be stabilized by π‐backbonding interactions with the former TiIIion, and their assembly to most likely involve a concerted E atom transfer between Ti‐bound OCEto AdNC ligands when studying the reaction coordinate for E=P.

     
    more » « less
  3. Abstract

    Decarbonylation along with E atom transfer from Na(OCE) (E=P, As) to an isocyanide coordinated to the tetrahedral TiIIcomplex [(TptBu,Me)TiCl], yielded the [(TptBu,Me)Ti(η3‐ECNAd)] species (Ad=1‐adamantyl, TptBu,Me−=hydrotris(3‐tert‐butyl‐5‐methylpyrazol‐1‐yl)borate). In the case of E=P, the cyanophosphide ligand displays nucleophilic reactivity toward Al(CH3)3; moreover, its bent geometry hints to a reduced Ad−NCP3−resonance contributor. The analogous and rarer mono‐substituted cyanoarsenide ligand, Ad−NCAs3−, shows the same unprecedented coordination mode but with shortening of the N=C bond. As opposed to TiII, VIIfails to promote P atom transfer to AdNC, yielding instead [(TptBu,Me)V(OCP)(CNAd)]. Theoretical studies revealed the rare ECNAd moieties to be stabilized by π‐backbonding interactions with the former TiIIion, and their assembly to most likely involve a concerted E atom transfer between Ti‐bound OCEto AdNC ligands when studying the reaction coordinate for E=P.

     
    more » « less
  4. Abstract

    3,3′,5,5′‐Tetra‐tert‐butyl‐2′‐sulfanyl[1,1′‐biphenyl]‐2‐ol (H2[tBu4OS]) was prepared in 24 % yield overall from the analogous biphenol using standard techniques. Addition of H2[tBu4OS] to Mo(NAr)(CHCMe2Ph)(2,5‐dimethylpyrrolide)2led to formation of Mo(NAr)(CHCMe2Ph)[tBu4OS], which was trapped with PMe3to give Mo(NAr)(CHCMe2Ph)[tBu4OS](PMe3) (1(PMe3)). An X‐ray crystallographic study of1(PMe3) revealed that two structurally distinct square pyramidal molecules are present in which the alkylidene ligand occupies the apical position in each. Both1(PMe3)Aand1(PMe3)Bare disordered. Mo(NAd)(CHCMe2Ph)(tBu4OS)(PMe3) (2(PMe3); Ad=1‐adamantyl) and W(NAr)(CHCMe2Ph)(tBu4OS)(PMe3) (3(PMe3)) were prepared using analogous approaches.1(PMe3) reacts with ethylene (1 atm) in benzene within 45 minutes to give an ethylene complex Mo(NAr)(tBu4OS)(C2H4) (4) that is isolable and relatively stable toward loss of ethylene below 60 °C. An X‐ray study shows that the bond distances and angles for the ethylene ligand in4are like those found for bisalkoxide ethylene complexes of the same general type. Complex1(PMe3) in the presence of one equivalent of B(C6F5)3catalyzes the homocoupling of 1‐decene, allyltrimethylsilane, and allylboronic acid pinacol ester at ambient temperature.1(PMe3),2(PMe3), and3(PMe3) all catalyze the ROMP ofracendo,exo‐5,6‐dicarbomethoxynorbornene (rac‐DCMNBE) in the presence of B(C6F5)3, but the polyDCMNBE that is formed has a random structure.

     
    more » « less
  5. Abstract

    Reactions of the IrVhydride [MeBDIDipp]IrH4{BDI=(Dipp)NC(Me)CH(Me)CN(Dipp); Dipp=2,6‐iPr2C6H3} with E[N(SiMe3)2]2(E=Sn, Pb) afforded the unusual dimeric dimetallotetrylenes ([MeBDIDipp]IrH)2(μ2‐E)2in good yields. Moreover, ([MeBDIDipp]IrH)2(μ2‐Ge)2was formed in situ from thermal decomposition of [MeBDIDipp]Ir(H)2Ge[N(SiMe3)2]2. These reactions are accompanied by liberation of HN(SiMe3)2and H2through the apparent cleavage of an E−N(SiMe3)2bond by Ir−H. In a reversal of this process, ([MeBDIDipp]IrH)2(μ2‐E)2reacted with excess H2to regenerate [MeBDIDipp]IrH4. Varying the concentrations of reactants led to formation of the trimeric ([MeBDIDipp]IrH2)3(μ2‐E)3. The further scope of this synthetic route was investigated with group 15 amides, and ([MeBDIDipp]IrH)2(μ2‐Bi)2was prepared by the reaction of [MeBDIDipp]IrH4with Bi(NMe2)3or Bi(OtBu)3to afford the first example of a “naked” two‐coordinate Bi atom bound exclusively to transition metals. A viable mechanism that accounts for the formation of these products is proposed. Computational investigations of the Ir2E2(E=Sn, Pb) compounds characterized them as open‐shell singlets with confined nonbonding lone pairs at the E centers. In contrast, Ir2Bi2is characterized as having a closed‐shell singlet ground state.

     
    more » « less