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New 1,2,3-triazole based bis- and trisphosphine ligands: synthesis, transition metal chemistry and catalytic studies

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Abstract

The syntheses and transition metal chemistry of triazole-based bis- and tris-phosphines, 5-(diphenylphosphanyl)-1-(2-(diphenylphosphanyl)phenyl)-4-phenyl-1H-1,2,3-triazole (2), 5-(diphenylphosphanyl)-4-(2-(diphenylphosphanyl)phenyl)-1-phenyl-1H-1,2,3-triazole (5), 1,4-bis(2-(diphenylphosphanyl)phenyl)-1H-1,2,3-triazole (6) and 5-(diphenylphosphanyl)-1,4-bis(2-(diphenylphosphanyl)phenyl)-1H-1,2,3-triazole (7), are described. Bisphosphines 5 and 6 show versatile coordination behavior due to the presence of at least four donor atoms. The reactions of 5 and 6 with group VI metal carbonyl derivatives were found to be highly sensitive to the reaction conditions. Bisphosphine 5 upon treatment with [M(CO)4(piperidine)2] (M = Mo and W) yielded both P,P and P,N coordinated complexes [M(CO)4(5)] [M = Mo-κ2-P,N (8); W-κ2-P,N (9); Mo-κ2-P,P (10); W-κ2-P,P (11)], whereas 6 afforded only P,N coordinated complexes [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))CH}-κ2-P,N}Mo(CO)4] (12) and [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))CH}-κ2-P,N}W(CO)4] (13). The reactions of 5 with [M(COD)Cl2] (M = Pd and Pt) yielded κ2-P,P chelate complexes 14 and 15, respectively, whereas the treatment of 6 with [Pd(COD)Cl2] at ambient temperature resulted in the formation of a rare fused six-membered PCP pincer complex [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))C}-κ3-P,C,P}PdCl] (16). Similar reactions of 6 with [NiCl2(DME)] and [Pt(COD)Cl2] in the presence of LiHMDS yielded [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))C}-κ3-P,C,P}NiCl] (17) and [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))C}-κ3-P,C,P}PtCl] (18), respectively. The reaction between 6 and [M(COD)Cl]2 (M = Rh and Ir) produced cationic complexes [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))CH}-κ2-P,N}Rh(C8H12)]Cl (19) and [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))CH}-κ2-P,N}Ir(C8H12)]Cl (20), respectively, whereas the reaction with [Rh(acac)(CO)2] resulted in a pincer complex [{o-Ph2P(C6H4){1,2,3-N3C(o-Ph2P(C6H4))C}-κ3-P,C,P}Rh(CO)] (21). The structures of most of the compounds have been determined by single crystal X-ray analyses. The fused six-membered PCP palladium pincer complex 16 is found to be an excellent catalyst for the Mizoroki–Heck coupling reaction.

Graphical abstract: New 1,2,3-triazole based bis- and trisphosphine ligands: synthesis, transition metal chemistry and catalytic studies

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Supplementary files

Article information


Submitted
06 Nov 2019
Accepted
01 Jan 2020
First published
02 Jan 2020

Dalton Trans., 2020, Advance Article
Article type
Paper

New 1,2,3-triazole based bis- and trisphosphine ligands: synthesis, transition metal chemistry and catalytic studies

L. Radhakrishna, H. S. Kunchur, P. K. Namdeo, R. J. Butcher and M. S. Balakrishna, Dalton Trans., 2020, Advance Article , DOI: 10.1039/C9DT04302K

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