Novel rare earth quinolinolate complexes

Syntheses at Elevated Temperature and Structures of Lanthanoid/Alkaline Earth Heterobimetallic Derivatives of 2‐Methyl‐8‐hydroxyquinoline

“…The hexacoordinate alkaline earth metal is surrounded by the oxygen atoms in a distorted octahedral arrangement ( Figure S1). This motif (Scheme 1) has previously been observed in [Ln 2 Ca(OQ) 8 ] (Ln = Nd, Eu) complexes, [12,14] and the connectivity is the same in molecule Mg(2) (Figure 1). Bond length data (Table 1) show a somewhat variable response to the decrease in ionic radii (0.062 Å) [16] (Figure 2, vide infra), which is possibly attributable to greater crowding in the heterobimetallics.…”

“…Barium is coordinated by seven oxygen atoms, from five chelatingbridging ligands and two chelating-bridging tridentate ligands, and it is also ligated by a nitrogen atom from an MQ ligand that oxo-bridges between Ba(1) and Eu (2). Nitrogen bonding to the AE metal has not previously been observed in Ln/AE/MQ (above) (or OQ) [12,14] homoleptic complexes. Each of the two µ 3 -η 2 (N, O): (2).…”

“…[12,14] However, HMQ has succeeded where HOQ has so far failed in giving a lanthanum complex [18] (Figure 3). [12] Eu [14] ).…”

“…We have presented preliminary accounts of three pseudo-solid-state synthetic approaches to crystalline Ln/M heterobimetallic 8-quinolinolates, namely by: (i) reaction of a mixture of calcium and neodymium metals with 8-hydroxyquinoline at elevated temperatures to afford [Nd 2 Ca(OQ) 8 ] as single crystals in low yield together with bulk red amorphous glass, [12] (ii) reaction of HOQ with a LaNi 5 alloy at elevated temperatures giving [LaNi 2 (OQ) 7 ] [13] and (iii) rearrangement of a mixture of Ln(OQ) 3 and either Ca(OQ) 2 7 ], respectively. [14] 8-Hydroxyquinaldine (HMQ) is also a gravimetric reagent with a similar solubility profile for metal complexes, thereby posing similar problems for the synthesis of f-element/d-or alkaline earth element heterobimetallics. The close proximity of the methyl group to the N-donor centre may impose steric constraints on heterobimetallic complex formation.…”

Alkali Metal/Lanthanoid Heterobimetallic Complexes of 8‐Hydroxyquinolines Accessed by Pseudo‐Solid‐State Reactions

“…[11] More elaborate functionalisation has both enhanced solubility and synthesis and also gives rise to luminescent and light-emitting materials, including heterobimetallic compounds, [12] for example, alkali metal/lanthanoid complexes of highly functionalised (partly to achieve solubility) OQ ligands have recently been reported and show bright near-infrared luminescence. [13] The rare earth/alkaline earth [14][15][16] and rare earth/transition metal heterobimetallic complexes [Ln 2 AE(MQ or OQ) 8 ] and [LnTM 2 (OQ) 7 ] [15,17] are also highly insoluble, posing similar synthesis and crystallisation problems to homometallic lanthanoid OQ and MQ complexes. We have, however, developed pseudo-solid-state syntheses, for example, reactions of the mixed metals [14] or alloys, [17] with HOQ and rearrangement reactions of Ln(OQ or MQ) 3 and AE(OQ or MQ) 2 [15,16] or TM(OQ) 2 [15] species at elevated temperatures (150-300°C), alone or in a 1,2,4,5-tetrameth- 11 ] complexes.…”