Expanding Bismuth Trihalide Coordination Chemistry with Trimethyltriazacyclohexane and Trimethyltriazacyclononane

Abstract

1,3,5-Trimethyltriazacyclohexane, Me3tach, readily adds to bismuth triiodide to form a variety of new coordination compounds depending on the stoichiometry, solvent, and crystallization conditions. X-ray crystallographic evidence has been obtained for both 2:1 and 1:1 Me3tach:Bi complexes with formulas of [(Me3tach)2BiI2]­[(Me3tach)­BiI4], [(Me3tach)2BiI2]3[Bi2I9]­[I]­[HMe3tach]·THF, and (Me3tach)­BiI3(py)2. The related chloride structure (Me3tach)­BiCl3(py)2 forms from BiCl3. The structure of (Me3tacn)­BiI3 with the larger chelate, 1,4,7-trimethyltriazacyclononane, Me3tacn, was obtained for comparison, and the polymeric structure of BiI3 in THF was defined as [BiI­(THF)­(μ–I)2] n .

Trimethyltriazacyclohexane coordination chemistry of simple rare-earth metal salts

“…Similar resonances were observed for 1-Ce and the previously reported uranium and bismuth Me 3 tach compounds. 43,44 We find that some diamagnetic rare-earth metal compounds containing R 3 tach ligands have well-resolved NMR spectra and others do not. [30][31][32][33][34][35][36][37][38][39][40] Each 1-Ln complex has the LnI 3 unit sandwiched between two Me 3 tach ligands.…”

“…The closer contact of the chelate with the metal center for Me 3 tacn versus Me 3 tach has been observed in previous studies with 1-An 43 and with Bi complexes. 44 This has been attributed to the fact that the Me 3 tacn ligand is more flexible than Me 3 tach due to the ethylene linkers and can approach the metal closer. A comprehensive list of Me 3 tacn rare-earth metal complexes is tabulated in Table S2 the ESI† and consistently show shorter M–Cnt distances than analogous Me 3 tach complexes.…”

“…Hence, 3-La has only one unique value for the La-Cnt, La-N, and La-Cl distances, where Cnt is defined as the calculated centroid of the three nitrogen donor atoms. 43,44 As a result of the symmetry, the Cnt-La-Cnt angle in 3-La is exactly 180°, the Cnt-La-Cl angle is 90°, and the Cl-La-Cl angle is 120°. The La-Cnt distance in 3-La is 2.428 Å.…”

“…We report here on our initial studies with rare-earth metals that has already been extended to U, Np, and Pu chemistry 43 and to a study of Me 3 tach with bismuth halides. 44 The present coordination chemistry survey of Me 3 tach with rare-earth metal starting materials focuses on La( iii ) salts to make comparisons between iodide, chloride, and triflate complexes, as well as Me 3 tach and Me 3 tacn comparisons. Results with some other Ln( iii ) ions are included as well as some SmI 2 reactions.…”

Synthesis of Trimethyltriazacyclohexane (Me3tach) Sandwich Complexes of Uranium, Neptunium, and Plutonium Triiodides: (Me3tach)2AnI3

“…The 2.109 Å U−Cnt distance of 3 is much shorter than the 2.431 and 2.338 Å distances of 1-U and 2 even though it is a larger ligand. This difference has been observed before 16 and attributed to the greater flexibility of Me 3 tacn ligand which allows it to get closer to the metal. Since the ligand fills the coordination sphere to a greater extent, complex 3 is only seven-coordinate.…”