Molecular Zirconium Nitride Super Base from a Mononuclear Parent Imide

In this work, we prepared, isolated, and structurally characterized a zirconium complex having a terminally bound imide motif, (PN)2Zr≡NH (PN– = (N-(2-iPr2P-4-methylphenyl)-2,4,6-trimethylanilide)), along with the zirconium nitride complex {(PN)2Zr≡N[μ2-Li(THF)]}2. (PN)2Zr≡NH was prepared by reduction of trans-(PN)2Zr(N3)2 with KC8. Isotopic labeling and spectroscopic studies were conducted using the respective 15N enriched isotopologues, whereas solid-state structural studies confirmed some of the shortest Zr≡N distances known to date (Zr≡NH, 1.830(3) A; Zr≡N–, 1.822(2) A). It was found that the nitride in {(PN)2Zr≡N[μ2-Li(THF)]}2 is super basic and in the range of −36 to −43 pKb units. Computational studies have been applied to probe the bonding and structure for this new class of zirconium–nitrogen multiple bonds.