Title: Anhydrous vs Hydrated f-Element Acetate Polymers Dictated by the Stoichiometry of Protic Acidic/Basic Azole Mixtures

Abstract

Continuing our investigations of ionic liquid (IL) based routes to a library of f-element/soft donor complexes which could be studied crystallographically, we have explored the dissolution of f-element salts in protic imidazole-based ILs containing only soft donors at high temperatures to drive off volatiles, including water and carboxylic or mineral acids. Here we present our results, reacting acidic and basic azoles in 1:3 or 1:1 stoichiometric compositions at elevated temperature, followed by saturation with Nd(OAc)₃·xH₂O or Ce(OAc)₃·xH₂O, which led to 13 new metal–acetate polymeric complexes identified by single-crystal X-ray diffraction. We found that the diversity in coordination modes of the simple acetate ligand that interfere with substitution of the softer N donors led to several readily crystallizable complexes forming two distinct groups with respect to f-element interaction with the ionic liquid precursors. When the acidic/basic azole ratio was 1:3, acetate and a neutral basic azole were found to be coordinated to the metal centers but no water, although in one case (2) water was observed in the secondary coordination sphere: [Ce(μ₂-OAc)₃(C₁im)]_n (1, C₁im = 1-methylimidazole), [Nd(μ₂-(OAc)₃(C₁im)]_n·nH₂O (2), [Ce(μ₂-OAc)₃(C₂im)]_n (3, C₂im = 1-ethylimidazole), [Ln(μ₂-OAc)₃DMF]_n (Ln = Nd (4), Ce (5); dimethylformamide (DMF) was substituted for the azole mixture), and [Nd(μ₂-OAc)₃(C₄im)]_n (6,more » C₄im = 1-butylimidazole). However, when the stoichiometric ratio was 1:1, water was always observed coordinated to the metal ions with the acidic azole included in the structure as a solvate or cocrystal, despite a higher reaction temperature: [Nd(μ₂-OAc)₃(OH₂)]_n·n(1,2,3-Taz) (7, 1,2,3-Taz = 1,2,3-triazole), [Ln(μ₂-OAc)₃(OH₂)]_n·n(4,5-DCim) (Ln = Nd (8), Ce (9), 4,5-DCim = 4,5-dicyanoimidazole), [Ln(μ₂-OAc)₃(OH₂)]_n·n(3,5-diNH₂-1,2,4-Taz) (Ln = Nd (10), Ce (11), 3,5-diNH₂-1,2,4-Taz = 3,5-diamino-1,2,4-triazole), [Ce(μ₂-OAc)₃(OH₂)]_n·n(3-NH₂-1,2,4-Taz) (12, 3-NH₂-1,2,4-Taz = 3-amino-1,2,4-triazole), and [Nd(μ₂-OAc)₃(OH₂)]_n·n(5-NH₂-Tz) (13, 5-NH2-Tz = 5-aminotetrazole). All of the compounds retain the Ln:OAc– ratio of 1:3 and form 1D polymeric chains; however, they exhibit a variety of coordination modes affecting the degree of chain condensation. The isolation of both hydrated and anhydrous products revealed different abilities of the investigated soft N-donors to compete with O-donors finding their place in the coordination sphere of the lanthanide or in the crystal lattice.« less

Authors:

Nayak, Amrita ^[1]; Smetana, Volodymyr  ^[2];

• Search DOE PAGES for author "Smetana, Volodymyr"
• Search DOE PAGES for ORCID "0000-0003-0763-1457"

Mudring, Anja-Verena  ^[2];

• Search DOE PAGES for author "Mudring, Anja-Verena"
• Search DOE PAGES for ORCID "0000-0002-2800-1684"

Rogers, Robin D.  ^[3]

• Search DOE PAGES for author "Rogers, Robin D."
• Search DOE PAGES for ORCID "0000-0001-9843-7494"

---

+ Show Author Affiliations

1. Univ. of Alabama, Tuscaloosa, AL (United States)
2. Stockholm Univ. (Sweden)
3. Univ. of Alabama, Tuscaloosa, AL (United States); Stockholm Univ. (Sweden)

Publication Date:

Tue Mar 16 00:00:00 EDT 2021

Research Org.:

Univ. of Alabama, Tuscaloosa, AL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); Swedish Research Council (SRC); National Science Foundation (NSF)

OSTI Identifier:

1831277

Grant/Contract Number:  

SC0019220

Resource Type:

Accepted Manuscript

Journal Name:

Crystal Growth and Design

Additional Journal Information:

Journal Volume: 21; Journal Issue: 4; Journal ID: ISSN 1528-7483

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Salts; Metals; Ligands; Solvents; Organic compounds