Syntheses and Characterizations of Hetero-Bimetallic Chromium-Dinitrogen Transition-Metal Complexes

Abstract

In the domain of N2 activation, hetero-bimetallic dinitrogen complexes are garnering substantial interest due to their potential to induce polarization in nonpolar N2 gas. Herein, we present the syntheses and characterizations of three novel hetero-multimetallic dinitrogen complexes: Cp*Cr­(depe)­N2V­(depe) Me [O, P, O] 5, Cp*Cr­(depe)­N2V­(depe) Tipp [O, P, O] 6, and [Cp*Cr­(depe)­N2]2Ti Tipp [O, P, O] 7. These complexes were synthesized via a transmetalation process involving the treatment of [Cr0–N2]− complex 4 with vanadium and titanium chloride complexes bearing alkyl or aryl substituted bis­(o-hydroxyphenyl)-phenyl phosphine R [O, P, O] ligand (alkyl = methyl, aryl = 2,4,6-tri-isopropylbenzene). X-ray analysis shows that complexes 5 and 6 exhibit heterodinuclear structures, while complex 7 exhibits a heterotrinuclear core with two N2 ligands concurrently coordinated to two chromium and one titanium atoms. Raman spectroscopic data show that the N–N stretching vibration of the N2 moiety is clearly downshifted relative to free N2 and to mononuclear [Cr0–N2]− complex 4.

Coordination of Al(C6F5)3vs. B(C6F5)3 on group 6 end-on dinitrogen complexes: chemical and structural divergences

“…To the best of our knowledge, these compounds are the first examples of trinuclear heterometallic complexes formed by Lewis acid–base interaction exhibiting p and d elements. Among the handful of N 2 -bridged trinuclear heterobimetallic species 88–98 of general formula M 1 (μ-N 2 )M 2 (μ-N 2 )M 1 (M 1 = Cr, 89 Mo, 95–97 Re, 92 Fe, 93 Co; 90,91,93,94,98 M 2 = Na, 95 Mg, 90,91,93–95,97,98 Ti, 89 Zr, 92,96 V, 96 Fe 96 ), many are based on a low diversity of metal/metal couples, typically on magnesium/early transition metals pairs, as a result of a formally anionic dinitrogen complex formed by reduction with an alkaline or alkaline-earth metal. For the synthesis of d-block-only congeners, a general strategy consists in halide substitution by an electron-rich N 2 ligand, a transformation that accompanies with formal oxidation of the N 2 -ligated metal centre concomitant with reduction of N 2 .…”

Iron promoted end-on dinitrogen-bridging in heterobimetallic complexes of uranium and lanthanides

“…4,5 N 2 bridged heterometallic complexes were reported in seminal studies more than 50 years ago [6][7][8][9][10][11][12][13][14][15] but the use of mid-tolate d-elements such as iron 16,17 remains rare. Recently, N 2 bridged heterobimetallic complexes [18][19][20][21][22] have attracted increasing interest in transition metal chemistry for their potential to produce more polarized, and therefore more reactive, dinitrogen via a "push-pull" activation. 16,17,[23][24][25] However, Lewis acid-base interaction remains a difficult and underdeveloped route to the synthesis of heterobimetallic N 2 complexes.…”