Synthesis, structures, and reactions of titanium, scandium, and yttrium complexes of diamino-bis(phenolate) ligands: Monomeric, dimeric, neutral, cationic, and multiply bonded derivatives

Boyd, C. L., Toupance, T., Tyrrell, B. R., Ward, Benjamin David ORCID: https://orcid.org/0000-0003-1406-5940, Wilson, C. R., Cowley, A. R. and Mountford, P. 2005. Synthesis, structures, and reactions of titanium, scandium, and yttrium complexes of diamino-bis(phenolate) ligands: Monomeric, dimeric, neutral, cationic, and multiply bonded derivatives. Organometallics 24 (2) , pp. 309-330. 10.1021/om0493661

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Abstract

New groups 3 and 4 organometallic and coordination compounds supported by the tetradentate diamino-bis(phenolate) ligands O2tBuNN‘ and O2MeNN‘ are reported [H2O2RNN‘ = (2-C5H4N)CH2N(2-HO-3,5-C6H2R2)2 where R = tBu or Me] along with some comparative studies with the tridentate amino-bis(phenolate) ligand O2tBuN (H2O2tBuN = nPrN(2-HO-3,5-C6H2tBu2)2). Reaction of Na2O2tBuNN‘ with ScCl3 and pyridine in THF gave monomeric Sc(O2tBuNN‘)Cl(py) (2), whereas Na2O2MeNN‘ gave the dimeric phenoxy-bridged Sc2(O2MeNN‘)2Cl2 (3). Reaction of Na2O2tBuNN‘ and YCl3 in neat pyridine gave the chloride-bridged, seven-coordinate dimer Y2(O2tBuNN‘)2(μ-Cl)2(py)2 (4). Reaction of M(CH2SiMe3)3(THF)2 (M = Sc or Y) with H2O2tBuNN‘ afforded M(O2tBuNN‘)(CH2SiMe3)(THF). The one-pot reaction of ScCl3 with Na2O2RNN‘ (R = tBu or Me) and Li[PhC(NSiMe3)2] gave the fluxional benzamidinate derivatives Sc(O2RNN‘){PhC(NSiMe3)2}. Treatment of Ti(NMe2)4 with H2O2RNN‘ gave the corresponding Ti(O2RNN‘)(NMe2)2 (R = tBu (11) or Me); 11 in turn reacts with HS-4-C6H4Me to give Ti(O2tBuNN‘)(NMe2)(S-4-C6H4Me). One-pot reactions of TiCl4(THF)2 with MeLi (2 equiv) followed by H2O2RNN‘ affords Ti(O2RNN‘)Cl2 (R = tBu (9) or Me (10)), which are cleanly methylated with MeMgBr to yield the corresponding Ti(O2RNN‘)Me2 (R = tBu (14) or Me (15)). The terminal imidotitanium compounds Ti(O2tBuNN‘)(NR)(py) (R = tBu or 2,6-C6H3Me2) were formed from the respective Ti(NR)Cl2(py)3 reagents and Na2O2tBuNN‘, and these react with CO2 by imido group transfer to yield the μ-oxo dimer Ti2(O2tBuNN‘)2(μ-O)2 (18) and RNCO. The related five-coordinate compounds Ti(O2tBuN)(NR)(py) (R = tBu, 2,6-C6H3Me2 (20) or 2,6-C6H3iPr2 (21)) were prepared in an analogous manner. These do not give identifiable metal products with CO2. Treatment of the dimethyl compounds 14 or 15 with B(ArF)3 or [CPh3][B(ArF)4] (ArF = C6F5) gave the fluxional, dimeric phenoxy-bridged cations [Ti2(O2RNN‘)2Me2]2+, which show very sluggish 1-hexene polymerization behavior. The compounds 2, 3, 4, 11, 9, 10, 16, 18, 20, and 21 have been crystallographically characterized.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Publisher:	American Chemical Society
ISSN:	0276-7333
Last Modified:	18 Oct 2022 12:24
URI:	https://orca.cardiff.ac.uk/id/eprint/9716

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