A Planar Three-Coordinate Vanadium(II) Complex and the Study of Terminal Vanadium Nitrides from N₂: A Kinetic or Thermodynamic Impediment to N–N Bond Cleavage?

Abstract

We report the first mononuclear three-coordinate vanadium(II) complex [(nacnac)V(ODiiP)] and its activation of N2 to form an end-on bridging dinitrogen complex with a topologically linear V(III)N2V(III) core and where each vanadium center antiferromagnetically couples to give a ground state singlet with an accessible triplet state as inferred by HFEPR spectroscopy. In addition to investigating the conversion of N2 to the terminal nitride (as well as the microscopic reverse process), we discuss its similarities and contrasts to the isovalent d(3) system, [Mo(N[(t)Bu]Ar)3], and the S = 1 system [(Ar[(t)Bu]N)3Mo]2(μ2-η(1):η(1)-N2).

Molecular titanium nitrides: nucleophiles unleashed

“…Akin to vanadium( ii ) dinitrogen complexes prepared in our group, we propose the rigid PN ligands in a putative species such as 2 2– ( 2 2– represents 2 being reduced by two electrons) to disfavor the mixing of triplet and singlet subspaces that is critical for the dinitrogen cleavage process. 62 In addition, the reactive nature of 1 suggests the formation of a nitride from N 2 to be thermodynamically less stable than 2 2– , a common trait also observed in vanadium nitrides versus dinitrogen complexes. Compound 2 is remarkably stable, failing to react with electrophiles as well as reductants, and further attempts to functionalize the N 2 have been unsuccessful.…”

Formation and Reactivity of the Terminal Vanadium Nitride Functionality

“…Infrared spectroscopy was performed with a Thermo Nicolet 6700 FTIR instrument equipped with software under PC control. NaN 3 was purified by stirring in anhydrous THF overnight, and the resulting white solids were collected by filtration (washed with several portions of THF, then Et 2 O) and dried under vacuum for 24 h. The synthesis of [(nacnac)VϵN(Ntol 2 )] (3), [18] [(nacnac)VCl(OAr)], [55] [(nacnac)VϵN(OAr)] (4), [55] [(nacnac)V(Ntol 2 )], [82] and [(nacnac)-VCl(Ntol 2 )] [82] are reported elsewhere. NaOAr was obtained from the deprotonation of commercially available HOAr and NaN-(SiMe 3 ) 2 in Et 2 O, followed by filtration of the solid.…”

“…As reported earlier, complex 4 has been fully characterized by multinuclear NMR ( 1 H, 13 C, and 51 V) and IR vibrational spectroscopy. [54,55] …”

Crystal structure of (N,N′-bis(2-(((2,6-diisopropylphenyl)imino)methyl)phenyl)benzene-1,2-diamido-κ4 O,O′,O′′,O′′′)oxidovanadium(IV), C44H48N4OV

“…The bond length between V1 and O1 (1.580(2) Å) is typical for ve-coordinate vanadyl species, which is found in other V = O containing complexe [8]. The o-phenylenediamine groups with the two amine nitrogen atoms (N3, N4) are bonded to the V atom with a distance of 2.015(3) Å and 2.016(3) Å, respectively, which are shorter than that of V1-N1 (2.122(2) Å) and V1-N2 (2.182(3) Å), and each of them is in the common range [9,10]. The angles between N2-V1-N3 (85.75(10)°), and for N1-V1-N4 (82.09(10)°) are in accordance with the bite angles found for a similar vanadium complex with the tetradentate ligand [11].…”