Reactions of the IrVhydride [MeBDIDipp]IrH4{BDI=(Dipp)NC(Me)CH(Me)CN(Dipp); Dipp=2,6‐
- Award ID(s):
- 1954612
- NSF-PAR ID:
- 10228595
- Date Published:
- Journal Name:
- Dalton Transactions
- Volume:
- 50
- Issue:
- 6
- ISSN:
- 1477-9226
- Page Range / eLocation ID:
- 2083 to 2092
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract i Pr2C6H3} with E[N(SiMe3)2]2(E=Sn, Pb) afforded the unusual dimeric dimetallotetrylenes ([MeBDIDipp]IrH)2(μ 2‐E)2in good yields. Moreover, ([MeBDIDipp]IrH)2(μ 2‐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(μ 2‐E)2reacted with excess H2to regenerate [MeBDIDipp]IrH4. Varying the concentrations of reactants led to formation of the trimeric ([MeBDIDipp]IrH2)3(μ 2‐E)3. The further scope of this synthetic route was investigated with group 15 amides, and ([MeBDIDipp]IrH)2(μ 2‐Bi)2was prepared by the reaction of [MeBDIDipp]IrH4with Bi(NMe2)3or Bi(Ot Bu)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. -
null (Ed.)The bis(imido) complexes (BDI)Nb(N t Bu) 2 and (BDI)Nb(N t Bu)(NAr) (BDI = N , N ′-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate; Ar = 2,6-diisopropylphenyl) were shown to engage in 1,2-addition and [2 + 2] cycloaddition reactions with a wide variety of substrates. Reaction of the bis(imido) complexes with dihydrogen, silanes, and boranes yielded hydrido-amido-imido complexes via 1,2-addition across Nb-imido π-bonds; some of these complexes were shown to further react via insertion of carbon dioxide to give formate-amido-imido products. Similarly, reaction of (BDI)Nb(N t Bu) 2 with tert -butylacetylene yielded an acetylide-amido-imido complex. In contrast to these results, many related mono(imido) Nb BDI complexes do not exhibit 1,2-addition reactivity, suggesting that π-loading plays an important role in activating the Nb–N π-bonds toward addition. The same bis(imido) complexes were also shown to engage in [2 + 2] cycloaddition reactions with oxygen- and sulfur-containing heteroallenes to give carbamate- and thiocarbamate-imido complexes: some of these complexes readily dimerized to give bis-μ-sulfido, bis-μ-iminodicarboxylate, and bis-μ-carbonate complexes. The mononuclear carbamate imido complex (BDI)Nb(NAr)(N( t Bu)CO 2 ) ( 12 ) could be induced to eject tert -butylisocyanate to generate a four-coordinate terminal oxo imido intermediate, which could be trapped as the five-coordinate pyridine or DMAP adduct. The DMAP adducted oxo imido complex (BDI)NbO(NAr)(DMAP) ( 16 ) was shown to engage in 1,2-addition of silanes across the Nb-oxo π-bond; this represents a new reaction pathway in group 5 chemistry.more » « less
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Abstract A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡C
t Bu) (2 ) (Menacnac−=[ArNC(CH3)]2CH, Ar=2,6‐i Pr2C6H3), was prepared upon treatment of the vanadium neopentylidyne complex (Menacnac)V≡Ct Bu(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≡Ct Bu)} (4 ), was obtained via the reaction of Na(OCP)(diox)2.5and ([ArNC(CH2)]CH[C(CH3)NAr])V≡Ct Bu(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≡Ct Bu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes,2 and4 , 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 complexes2 and4 . This study represents the first example of a metathesis reaction between the P‐atom of [PCO]−and an alkylidyne ligand. -
Abstract A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡C
t Bu) (2 ) (Menacnac−=[ArNC(CH3)]2CH, Ar=2,6‐i Pr2C6H3), was prepared upon treatment of the vanadium neopentylidyne complex (Menacnac)V≡Ct Bu(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≡Ct Bu)} (4 ), was obtained via the reaction of Na(OCP)(diox)2.5and ([ArNC(CH2)]CH[C(CH3)NAr])V≡Ct Bu(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≡Ct Bu moiety, followed by a reductive decarbonylation to form the V−C≡O linkage. The nature of the electronic ground state in diamagnetic complexes,2 and4 , 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 complexes2 and4 . This study represents the first example of a metathesis reaction between the P‐atom of [PCO]−and an alkylidyne ligand. -
Abstract Decarbonylation along with E atom transfer from Na(OCE) (E=P, As) to an isocyanide coordinated to the tetrahedral TiIIcomplex [(Tp
t Bu,Me)TiCl], yielded the [(Tpt Bu,Me)Ti(η3‐ECNAd)] species (Ad=1‐adamantyl, Tpt Bu,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 [(Tpt Bu,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 OCE−to AdNC ligands when studying the reaction coordinate for E=P.