Unexpected Dimeric Spiro‐Borate Complexes from Lewis‐Acid Induced Transformation of Oxalatoborates

Abstract

Oxalatoborates were transformed into dimeric spiro‐borate complexes by abstraction of oxalate ligands by Lewis acidic lanthanide trichlorides. Oxalatoborates with different anions and cations were investigated containing either bis‐oxalatoborate or catecholato‐oxalatoborate anions and lithium as well as EMIM (1‐ethyl‐3‐methyl‐imidazolium) and BMIM cations (1‐n‐butyl‐3‐methyl‐imidazolium) from the respective ionic liquids (ILs). Depending on the amount of oxalate groups and the different cations, the oxalate groups are partly or fully abstracted and transferred to the lanthanides. The reaction of anhydrous PrCl3 with Li[B(C6H4O2)(C2O4)] (lithium catecholato‐oxalatoborate = Li[Catbox]) in pyridine (py) led to a conversion of the borate anion to the complex [B2O(C6H4O2)(py)4][PrCl5(py)] (1). The use of the ILs [EMIM][Catbox] and [BMIM][Catbox] indicates complete transfer of the oxalate groups to the lanthanide ions in reactions with lanthanide chlorides and nitrates yielding the well‐known lanthanide oxalates Ln2(C2O4)3·10H2O (Ln = La, Eu). In contrast, the reaction of anhydrous YCl3 with Li[B(C2O4)2] (lithium bis‐oxalatoborate = Li[BOB]) in N,N‐dimethylformamide (dmf) results in the formation of [B2O(C2O4)2(dmf)2] (2). Transfer of one oxalate group per boron onto the yttrium ion is revealed by the formation of the one‐dimensional coordination polymer ∞1[LiYCl2(C2O4)(dmf)3] (3) as additional product. The products were characterized by single‐crystal X‐ray diffraction as well as powder X‐ray diffraction, IR spectroscopy and elemental analysis.

Transformation of [EMIm][BPB] into a Cationic Luminescent Ln‐Coordination Polymer with the Bis(phthalato)borate Anion

“…Previous investigations concerning the reactivity of different spiroborates in the presence of lanthanide chlorides or nitrates revealed diverse findings. Whereas, reactions of lanthanide chlorides with Na[BSB] in pyridine lead to a variety of accessible products with intriguing luminescence features, syntheses with oxalatoborates rather showed a decomposition of the borate anions than coordination to the lanthanide cations . This is accompanied by the abstraction of an oxalato group by the lanthanide ions and the formation of thermodynamically stable products such as 1 ∞ [LiYCl 2 (C 2 O 4 )(dmf) 3 ] or Ln 2 (C 2 O 4 ) 3 · 10H 2 O ( Ln = La, Eu), if spiroborates such as Li[BOB] or [EMIm][Catbox] are used as reagents.…”

“…First investigations on the reactivity of various oxalatoborates such as Li[BOB] or [EMIm + ][Catbox] (EMIm + = 1‐ethyl‐3‐methyl‐imidazolium) in the presence of lanthanide chlorides or nitrates showed decomposition of the respective borate anion rather than a coordination to the lanthanide ions . However, recently, it was shown that [BSB] – anion could be utilized as functional ligand in the coordination polymers 1 ∞ [ Ln (BSB) 3 (py) 2 ] ( Ln = Y, La – Nd, Sm) and 2 ∞ [ Ln (BSB) 3 (py)] ( Ln = Sm, Eu, Tb, Dy, Er).…”

Statistic Replacement of Lanthanide Ions in Bis‐salicylatoborate Coordination Polymers for the Deliberate Control of the Luminescence Chromaticity

“…Still, mainly salts with alkaline metal or organic cations are known, [9] while the knowledge on the coordination of such spiroborate anions, e. g. for lanthanide coordination compounds, is limited. Investigations on the reactivity of different oxalatoborates, such as [EMIm][Catbox] or Li[BOB] (EMIm=1‐ethyl‐3‐methyl‐imidazolium) in the presence of lanthanide chlorides or nitrates even showed decomposition of the respective borate anion rather than a coordination to the lanthanide ions [10] . A few examples of Ln‐compounds are known of the anions tetra(methoxy)borate or catecholatoborate, namely [Ln{B(OCH 3 ) 4 }(NO 3 ) 2 (CH 3 OH) 2 ] (Ln=La, Pr, Nd) [11] and [{Na}{(sal) 3 Ln(B(OCH 3 ) 4 )Ln(sal) 3 }] n (sal=salicylato and Ln=Y, Nd, Eu−Lu) [12] and [(η 2 ‐catecholato‐μ‐catecholatoborate) 3 Ln(thf) 3 ]⋅thf (Ln=Nd, Sm) [13] .…”

“…Investigations on the reactivity of different oxalatoborates, such as [EMIm][Catbox] or Li [BOB] (EMIm = 1-ethyl-3-methyl-imidazolium) in the presence of lanthanide chlorides or nitrates even showed decomposition of the respective borate anion rather than a coordination to the lanthanide ions. [10] A few examples of Ln-compounds are known of the anions tetra(methoxy)borate or catecholatoborate, namely [Ln{B(OCH 3 ) 4 }(NO 3 ) 2 (CH 3 OH) 2 ] (Ln=La, Pr, Nd) [11] and [{Na} {(sal) 3 Ln(B(OCH 3 ) 4 )Ln(sal) 3 }] n (sal = salicylato and Ln=Y, Nd, EuÀ Lu) [12] and [(η 2 -catecholato-μ-catecholatoborate) 3 Ln(thf) 3 ]•thf (Ln=Nd, Sm). [13] In this context, we could also show that the low-melting salt [EMIm][BPB] ([BPB] À = bis(phthalato)borate anion; [B{(C 6 H 4 )(CO 2 CO 2 )} 2 ] À ) could be transformed into a coordination polymer together with Tb 3 + , 1…”

Bis(salicylato)borate as Versatile Sensitizer for Highly Luminescent Lanthanide Oxoborates from the Ultraviolet to Near Infrared with 4f and 5d Participation of the Lanthanides

“…Although Li[BOB] and its derivatives, such as lithium (catecholato)oxalatoborate (Li[Catbox]), are of interest for electrochemical applications, there is limited knowledge about the behaviour of these salts in coordination chemistry, except for the crystal structure of Li[BOB] and some solvates, for example, Li[BOB] · H 2 O . Some insights have been gained recently, and an unexpected transformation of the aforementioned oxalatoborates to dimeric spiroborate complexes through oxalate splitting was observed . Closely related to Li[BOB] is lithium bis(salicylato)borate (Li[BSB]), the electrochemical features of which have also been discussed .…”