Heterometallic Complexes Containing Lanthanides

Abstract

The synthesis of tetranuclear gold complexes, as tructurally unprecedented octanuclear complex with ap lanar [Au I 8 ]c ore,a nd pentanuclear [Au I 4 M I ](M = Cu, Ag) complexes is presented. The linear [Au I 4 ]complex undergoes C À Hf unctionalization of carbonyl compounds under mild reaction conditions.I na ddition, [Au I 4 Ag I ]c atalyzes the carbonylation of primary amines to form ureas under homogeneous conditions with efficiencies higher than those achieved by gold nanoparticles. Following the pioneering work of the groups of Hutchings [1] and Haruta [2] on the oxidation of hydrocarbons and CO,many gold clusters and nanoparticles have been structurally characterized and studied in catalysis. [3,4] Recently,s mall gold clusters have been found to activate the CÀIb ond of iodobenzene in the gas phase [5] and to catalyze reactions usually performed by mononuclear gold complexes. [6] However ,t he actual structures of these clusters have not been determined. In this context, it is important to note that the group of Bertrand reported the synthesis of mixed-valence trinuclear [Au 0 2 Au I ]c lusters which are catalysts for the carbonylation of aliphatic amines under homogeneous conditions. [7] As part of our program on the study of the catalytic activity of well-defined gold(I) clusters, [8] we now report ar eady synthesis of linear [Au 4 ], pentagonal [Au I 4 M I ](M= Cu, Ag), and octagonal [Au 8 ]c omplexes.T he linear [Au 4 ] complex reacts with carbonyl compounds by CÀHf unction-alization to form square-planar complexes.F urthermore,t he pentanuclear complex [Au I 4 Ag I ]h as been found to be an excellent homogeneous catalyst for the carbonylation of amines. Our synthesis started from the dinuclear gold(I) complex 1,w hich is quantitatively prepared by mixing 2,6-bis(diphe-Scheme 1. Synthesis of the [Au 4 ]c omplexes 2 and 3 and the [Au 8 ] complex 4.A= SbF 6 ,B= BF 4 .

Distributive Nd-to-Yb Energy Transfer within Pure [YbNdYb] Heterometallic Molecules

“…In this respect, an optimal mode of implementing it is building up the antenna and the emissive center into discrete molecules. ,,− This is advantageous because chemical synthesis and design allow incorporating a large variety of organic sensitizers, tuning the distances between energy donors and acceptors, incorporating other functional properties, or tailoring the molecular properties for their processability. In this regard, probing Ln-to-Ln′ (Ln ≠ Ln′) ET within molecules is not an easy task because it requires the preparation of pure heterometallic species with the different Ln metal ions positioned selectively at specific locations of the molecular architecture. , Since the 4f valence electrons of lanthanides are strongly shielded by 5p and 5s electrons, they exhibit very similar reactivity; therefore, site-selective heterometallic Ln molecules are generally obtained via sequential methodologies that are very tedious. , These include (i) step-by-step deprotection/opening of coordination sites, (ii) covalent linkage of different preformed coordination complexes, − (iii) sequential activation and complexation of coordination sites, − or (iv) enantiomeric self-recognition and mutual binding of chiral components . Some of the valuable molecules obtained in these manners have afforded the opportunity to study for the first time interesting intramolecular Ln-to-Ln′ ET phenomena, such as Tb-to-Yb, , Tb-to-Er, or Dy-to-Tb .…”

“… 39 , 40 Since the 4f valence electrons of lanthanides are strongly shielded by 5p and 5s electrons, they exhibit very similar reactivity; therefore, site-selective heterometallic Ln molecules are generally obtained via sequential methodologies that are very tedious. 41 , 42 These include (i) step-by-step deprotection/opening of coordination sites, 43 (ii) covalent linkage of different preformed coordination complexes, 44 − 50 (iii) sequential activation and complexation of coordination sites, 51 − 58 or (iv) enantiomeric self-recognition and mutual binding of chiral components. 59 Some of the valuable molecules obtained in these manners have afforded the opportunity to study for the first time interesting intramolecular Ln-to-Ln′ ET phenomena, 41 such as Tb-to-Yb, 60 , 61 Tb-to-Er, 62 or Dy-to-Tb.…”

Distributive Nd-to-Yb Energy Transfer within Pure [YbNdYb] Heterometallic Molecules

“…[39][40] Since the 4f valence electrons of lanthanides are strongly shielded by 5p and 5s electrons, they exhibit very similar reactivity, therefore, site-selective heterometallic Ln molecules are generally obtained via sequential methodologies that are very tedious. [41][42] These include; i) step-by-step deprotection/opening of coordination sites, 43 ii) covalent linkage of different pre-formed coordination complexes, [44][45][46][47][48][49][50] iii) sequential activation and complexation of coordination sites, [51][52][53][54][55][56][57][58] or iv) enantiomeric self-recognition and mutual binding of chiral components. 59 Some of the valuable molecules obtained in these manners have afforded the opportunity to study for the first time interesting intramolecular Ln-to-Ln' ET phenomena, 41 such as Tb-to-Yb, [60][61] Tb-to-Er, 62 or Dy-to-Tb.…”