Issue 1, 2012
From the journal:

RSC Advances

Titanium and zirconium amido complexes supported by imidazole-containing ligands: syntheses, characterization and catalytic activities†

Yang Zhao,a   Miaoshui Lin,a   Zhou Chen,b   Hao Pei,a   Yahong Li,*ac   Yanmei Chen,b   Xiufang Wang,b   Lei Li,a   Yanyuan Cao,a   Yong Zhanga  and  Wu Lib  

* Corresponding authors

a Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, China
E-mail: liyahong@suda.edu.cn

b CAS Key Laboratory of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China

c State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, China

Abstract

A series of new titanium and zirconium amido complexes, incorporating 4,5-diphenyl-2-(2-pyridinyl)-1H-imidazole (HL1), 4,5-bis(4-chlorophenyl)-2-(2-pyridinyl)-1H-imidazole (HL2), 4,5-bis(4-methoxyphenyl)-2-(2-pyridinyl)-1H-imidazole (HL3) and 4,5-bis(2-methoxyphenyl)-2-(2-pyridinyl)-1H-imidazole) (HL4) as the ancillary ligands, have been prepared and are shown to be pre-catalysts for the hydroamination of alkynes. Treatment of Ti(NMe2)4 with 1 equivalent of HL1, HL2, HL3 and HL4, respectively, results in transamination with one dimethylamide group providing Ti(L1)(NMe2)3 (1), Ti(L2)(NMe2)3 (2), Ti(L3)(NMe2)3 (3), and Ti(L4)(NMe2)3·THF (4·THF). Reaction of Ti(NMe2)4 with 2 equivalents of HL1, HL2, HL3 and HL4, respectively, leads to production of titanium bisamido complexes Ti(L1)2(NMe2)2·THF (5·THF), Ti(L2)2(NMe2)2·THF (6·THF), Ti(L3)2(NMe2)2·THF (7·THF), and Ti(L4)2(NMe2)2 (8). Similarly, complexes Zr(L1)(NMe2)3 (9), Zr(L1)2(NMe2)2·1.5THF (10·1.5THF), Zr(L2)2(NMe2)2·0.5THF (11·0.5THF), and Zr(L3)2(NMe2)2·0.5THF (12·0.5THF) are generated by addition of 1 or 2 equivalents of the corresponding ligands to Zr(NMe2)4. All compounds have been characterized by elemental and spectroscopic analyses. The solid-state structures of compounds 2 and 6·THF have been further established by single X-ray diffraction analyses. The catalytic activities of 2 and 6·THF towards the hydroamination of alkynes were explored. Complexes 2 and 6·THF were found to be active pre-catalysts for the hydroamination reactions. Complex 2 showed higher catalytic activity and gave highly Markovnikov selective hydroamination of terminal alkynes.

Graphical abstract: Titanium and zirconium amido complexes supported by imidazole-containing ligands: syntheses, characterization and catalytic activities

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Supplementary files

Article information

DOI
https://doi.org/10.1039/C1RA00408E
Article type
Paper
Submitted
05 Jul 2011
Accepted
22 Aug 2011
First published
26 Oct 2011

RSC Adv., 2012,2, 144-150

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Titanium and zirconium amido complexes supported by imidazole-containing ligands: syntheses, characterization and catalytic activities

Y. Zhao, M. Lin, Z. Chen, H. Pei, Y. Li, Y. Chen, X. Wang, L. Li, Y. Cao, Y. Zhang and W. Li, RSC Adv., 2012, 2, 144 DOI: 10.1039/C1RA00408E

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