Homo- and Heterometallic Complexes of Tetra-(Di-Substituted Hydroxybenzyl)-N,N′-Ethylenediamine Derivatives

• Published in: Inorganic chemistry Vol. 48; no. 19; pp. 9191 - 9204
• Main Authors: Boyle, Timothy J., Pratt, Harry D., Ottley, Leigh Anna M., Alam, Todd M., McIntyre, Sarah K., Rodriguez, Mark A., Farrell, Joshua, Campana, Charles F.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.10.2009
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic900691a

The coordination behavior of a series of group 4 metal alkoxides [M(OR)4] modified by a set of novel substituted hydroxybenzyl ethylene diamine (H4-ED-L4) ligands {[tetra(3,5-di-t-butyl-2-hydroxybenzyl)-N,N′-ethylenediamine] termed H4-ED-DBP4 (1), [tetra(3,5-di-t-amyl-2-hydroxybenzyl)-N,N′-ethylenediamine] termed H4-ED-DAP4 (1a), and [tetra(3,5-dichloro-2-hydroxybenzyl)-N,N′-ethylenediamine] termed H4-ED-DCP4 (2)} was elucidated. The reaction of 1 or 1a with the M(OR)4 precursor led to the isolation of the structural similar species M(ED-L4) where L = DBP, M = Ti (3), Zr (4), Hf (5); L = DAP, M = Zr (4a), Hf (5a). In contrast, the reaction of 2 with the M(OR)4 precursors yielded Ti(ED-DCP4) (6), (py)2Zr(ED-DCP4) (7), and (HOBut)Hf(ED-DCP4) (8) where py = pyridine and HOBut = HOC(CH3)3. For 3−6, the cations of the monomeric species were completely encapsulated by all available heteroatoms (four O and two N) of the ED-L4 ligands, yielding an octahedral geometry for each metal center. For 7 and 8, an identical binding by the ED-DCP4 ligand was observed with the additional coordination of Lewis basic adducts, forming 8- and 7-coordinated metal centers, respectively. Switching to +2 cations led to the isolation of [(THF)Ca]2(ED-DBP4) (9a) where THF = tetrahydrofuran, {[(py)Ca]4(ED-(μ-DBP-η6)4)2} n (9b), and [(py)Zn](ED-DBP4)[Zn(py)2] (10) •5py and [(py)Sn]2(ED-DBP4) (11). The structures of these species were significantly different in arrangement compared to the Group 4 derivatives. Further attempts to produce a mixed +4/+2 cationic species yielded [(py)(ONep)2Ti(ED-DBP4)Zn(py)] (12). Reacting the single-source precursor Co[μ-OC6H4(CHMe2)2-2)2Li(py)2]2 with 1, led to the isolation of (py)Li[ED-DBP3(H-DBP)]Co (13), with one of the phenol protons remaining unreacted. The synthesis and characterization of these compounds are presented in detail.