Thomas Jarrod R, Mifsud Jonathan T, Sulway Scott A
School of Chemistry, The University of New South Wales (UNSW) Kensington Sydney 2052 Australia
RSC Adv. 2024 Sep 26;14(42):30713-30718. doi: 10.1039/d4ra05723f. eCollection 2024 Sep 24.
Though poly(pyrazolyl)borate ligands, namely dihydrobis(pyrazolyl)borate (Bp) and hydrotris(pyrazolyl)borate (Tp), have been used in coordination chemistry for decades, their synthesis and purification are of great importance, when targeting high purity and yield of metal complexes. As borohydride substitutions is temperature and pyrazolyl dependent, determining the reaction conditions for each ligand is non-trivial and does not always result in a temperature where only the desired products form. Herein we report the purification of two known Tp (R = phenyl, 2'-thienyl), as their -substituted temperatures coincide with their -temperatures fraction crystallisation from MeCN, and an optimised safe procedure for 3-aryl/heterocyclic Bp ligands (R = 2'-pyridyl, 2'-furyl, 2'-thineyl). These novel techniques allow for the safe isolation of alkali salts of poly(pyrazolyl)borate ligands in high yields and purities without the use of highly toxic thallium(i) salts.
尽管聚（吡唑基）硼酸酯配体，即二氢双（吡唑基）硼酸酯（Bp）和氢三（吡唑基）硼酸酯（Tp），已在配位化学中使用了数十年，但在以高纯度和高产率制备金属配合物时，它们的合成和纯化至关重要。由于硼氢化物取代取决于温度和吡唑基，确定每种配体的反应条件并非易事，而且并不总是能得到仅生成所需产物的温度。在此，我们报道了两种已知的Tp（R = 苯基，2'-噻吩基）的纯化方法，因为它们的α-取代温度与其β-温度一致——从乙腈中分级结晶，以及一种针对3-芳基/杂环Bp配体（R = 2'-吡啶基，2'-呋喃基，2'-噻吩基）的优化安全程序。这些新技术能够以高收率和高纯度安全分离聚（吡唑基）硼酸酯配体的碱金属盐，而无需使用剧毒的铊（I）盐。
