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Extended Hydrogen-Bonded Molybdenum Arrays Derived from Carboxylic Acids and Dianilines: ROP Capability of the Complexes and Parent Acids and Dianilines

Lookup NU author(s): Professor William Clegg, Dr Mark Elsegood

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Abstract

From reactions involving sodium molybdate and dianilines [2,2′ -(NH2 )C6H4 ]2 (CH2 )n (n = 0, 1, 2) and amino-functionalized carboxylic acids 1,2-(NH2 )(CO2H)C6H4 or 2-H2NC6H3 -1,4-(CO2H)2 , in the presence of Et3N and Me3SiCl, products adopting H-bonded networks have been characterized. In particular, the reaction of 2,2′ -diaminobiphenyl, [2,2′ -NH2 (C6H4 )]2 , and 2-aminoterephthalic acid, H2NC6H3 -1,4-(CO2H)2 , led to the isolation of [(MoCl3 [2,2′ -N(C6H4 )]2 }{HNC6H3 -1-(CO2 ),4- (CO2H)]·2[2,2′ -NH2 (C6H4 )]2 ·3.5MeCN (1·3.5MeCN), which contains intra-molecular N–H···Cl Hbonds and slipped π···π interactions. Similar use of 2,2′ -methylenedianiline, [2,2′ -(NH2 )C6H4 ]2CH2 , in combination with 2-aminoterephthalic acid led to the isolation of [MoCl2 (O2CC6H3NHCO2SiMe3 ) (NC6H4CH2C6H4NH2 )]·3MeCN(2·3MeCN). Complex 2 contains extensive H-bonds between pairs of centrosymmetrically-related molecules. In the case of 2,2′ ethylenedianiline, [2,2′ -(NH2 )C6H4 ]2CH2CH2 , and anthranilic acid, 1,2-(NH2 )(CO2H)C6H4 , reaction with Na2MoO4 in the presence of Et3N and Me3SiCl in refluxing 1,2-dimethoxyethane afforded the complex [MoCl3 {1,2-(NH)(CO2 )C6H4 }{NC6H4 CH2CH2C6H4NH3 }]·MeCN (3·MeCN). In 3, there are intra-molecular bifurcated H-bonds between NH3 H atoms and chlorides, whilst pairs of molecules H-bond further via the NH3 groups to the non-coordinated carboxylate oxygen, resulting in H-bonded chains. Complexes 1 to 3 have been screened for the ring opening polymerization (ROP) of both ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) using solvent-free conditions under N2 and air. The products were of moderate to high molecular weight, with wide Ð values, and comprised several types of polymer families, including OH-terminated, OBn-terminated (for PCL only), and cyclic polymers. The results of metal-free ROP using the dianilines [2,2′ -(NH2 )C6H4 ]2 (CH2 )n (n = 0, 1, 2) and the amino-functionalized carboxylic acids 1,2-(NH2 )(CO2H)C6H4 or 2-H2NC6H3 -1,4-(CO2H)2 under similar conditions (no BnOH) are also reported. The dianilines were found to be capable of the ROP of δ-VL (but not ε-CL), whilst anthranilic acid outperformed 2-aminoterephthalic acid for both ε-Cl and δ-VL.

Publication metadata

Author(s): Clegg W, Elsegood MRJ, Redshaw C

Publication type: Article

Publication status: Published

Journal: Catalysts

Year: 2024

Volume: 14

Issue: 3

Online publication date: 21/03/2024

Acceptance date: 15/03/2024

Date deposited: 21/03/2024

ISSN (electronic): 2073-4344

Publisher: MDPI AG

URL: https://doi.org/10.3390/catal14030214

DOI: 10.3390/catal14030214

Data Access Statement: Data is available upon requested.

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