N-aryloxide-amidinate group 4 metal complexes

Abstract

A N-aryloxide-amidine ligand (H3L), integrating phenoxide (PhO-) and amidine ligands through methylene linkers, has been synthesized from 2-(aminomethyl)-6-(tert-butyl)phenol in two steps. Upon reacting the deprotonated H3L ligand with group 4...

N-Aryloxide-Amidinate Thorium Complexes

“…The N-aryloxide-amidine ligand, 1, was prepared according to our previous work. 37 When trianion of 1, generated in situ, was reacted with ThCl 4 (DME) 2 in Et 2 O after 3 days, thorium dimer complex {[ONNO]Th IV Cl(LiCl)-(THF) 2 } 2 (2) was obtained (Scheme 1, eq 1). Our initial efforts to prepare oxygen-substituted variants by reacting 2 with Na 2 O led, unexpectedly, to the formation of dimer complex {{[ONNO]Th IV Cl} 4 (NaCl) 2 (THF) 8 } (3), where Na 2 O facilitated removing of inner salt, LiCl (Scheme 1, eq 2).…”

“…This trend may be attributed to the increase in the ionic radius of Th IV (effective ionic radius: Ti IV = 0.605 Å, Zr IV = 0.72 Å, Hf IV = 0.71 Å, Th IV = 1.05 Å; crystal radius: Ti IV 0.745 = Å, Zr IV = 0.86 Å, Hf IV = 0.85 Å, Th IV = 1.19 Å). 64 Similar to complex {[ONNO]-Ti IV Cl} 2 , 37 the aryloxide arms adopt an intersecting coordination mode, linking the two Th IV centers through the ArO − arms of the same ligand. The amidine moiety [N � C�N] − exhibits delocalization, akin to {[ONNO]Zr IV Cl} 2 , 37 as evidenced by the comparable C1−N1 and C1−N2 distances (1.348(4) Å and 1.327(5) Å).…”

“…Chemicals were purchased from commercial vendors if there was no special description. Ligand 1 was synthesized according to our previous work …”

“…two molecules of LiCl, in contrast to our previously reported six-coordinate group 4 metal complexes. 37 The comparative analysis reveals an increase in the average M−O(aryloxide) and M−N(amidine) distances from Ti IV , Hf IV , and Zr IV to Th IV (Ti IV −O = 1.817 Å, Hf IV −O = 1.952 Å, Zr IV −O = 1.971 Å, Th IV −O = 2.210 Å; Ti IV −N = 2.139 Å, Hf IV −N = 2.282 Å, Zr IV −N = 2.355 Å, Th IV −N = 2.653 Å). This trend may be attributed to the increase in the ionic radius of Th IV (effective ionic radius: Ti IV = 0.605 Å, Zr IV = 0.72 Å, Hf IV = 0.71 Å, Th IV = 1.05 Å; crystal radius: Ti IV 0.745 = Å, Zr IV = 0.86 Å, Hf IV = 0.85 Å, Th IV = 1.19 Å).…”

“…Ligand 1 was synthesized according to our previous work. 37 1 H NMR and 13 C NMR spectra were collected on a Bruker ARX 400 MHz spectrometer or a Bruker AVANCE III 500 MHz spectrometer using Toluene-d 8 , Pyridine-d 5 , C 6 D 6 , or THF-d 8 as solvents. FTIR spectra were recorded on a Bruker Alpha II FTIR spectrometer in the 400−4000 cm −1 region (KBr pellet).…”