A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡C
A low‐spin and mononuclear vanadium complex, (Menacnac)V(CO)(η2‐P≡C
- PAR ID:
- 10303963
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 60
- Issue:
- 46
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 24411-24417
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract 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. -
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Abstract We introduce the heterocumulene ligand [(Ad)NCC(
t Bu)]−(Ad=1‐adamantyl (C10H15),t Bu=tert ‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡Ct Bu(OTf)] (A ) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐i Pr2C6H3) and [(dBDI)V≡Ct Bu(OEt2)] (B ) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). ComplexA reacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N ‐ynamide ligand, [(BDI)V{κ1‐N ‐(Ad)NCC(t Bu)}(OTf)] (1 ). Conversely,B reacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C ,N ‐azaalleneyl ligand, [(dBDI)V{κ2‐N ,C ‐(Ad)NCC(t Bu)}] (2 ). Theoretical studies have been applied to better understand the mechanism of formation of2 and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between1 and2 . -
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Abstract Decarbonylation along with E atom transfer from Na(OCE) (E=P, As) to an isocyanide coordinated to the tetrahedral TiIIcomplex [(Tp
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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. -
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