Thulium divalent complexes

Treatment of thulium diiodide with substituted phospholide and arsolide salts afforded stable bis(phospholyl)- and bis(arsolyl)thulium(ll) complexes (Scheme 201) as green solids, that were characterized by multinuclear NMR and X-ray crystal structures. The latter clearly revealed the beneficial effects of the steric and electronic properties of crowded phospholyl and arsolyl ligands for the stabilization of divalent thulium.727 Several other homoleptic samarium(ll) and thulium(n) phospholyl sandwich complexes containing the 2,5-di-/-butyl-3,4-dimethylphospholide (=dtp) or 2,5-bis(trimethylsilyl)-3,4-dimethylphospholide (=dsp) ligand have been synthesized and structurally characterized. X-ray studies revealed that [Sm(dtp)2]2 and [Sm(dsp)2]2 are both dimeric in the solid state due to... 

A new breakthrough in the non-classical divalent rare-earth chemistry occurred in 1997, when Bochkarev and Evans in a milestone paper reported that a light-sensitive molecular complex of Tml2, identified as a solvate of composition [Tml2(DME)3] (Figure 1) (DME = 1,2-dimethox-yethane), could be made in relatively mild conditions by the direct reaction of thulium metal with iodine in refluxing DME (Scheme 1). 

Nief F, de Borms BT, Ricard L, Carmichael D. New complexes of divalent thulium with substituted phospholyl and cyclopentadienyl ligands. Eur I Inorg Chem. 2005 2005 637-643. 

The reaction of Sc2-naph with excess pyridine (Scheme 3B) led to the isolation of a rare, reductively 4,4 -C-C-coupled diamide linker that bridges the two scandium ions in the complex [(NN )Sc(NC5H5)]2[p-(NC5H5-C5H5N)]. A similar reduction was reported in the reactions of divalent thulium complexes (Fedushkin et al., 2003 Jaroschik et al., 2007b) and, recently, samarium(ll) (LabouiUe et al., 2012) with pyridine however, the reaction of a rare earth arene complex with pyridine had not been reported previously. 

Charge transfer bands result whenever an easily oxidized ligand is bound to a trivalent lanthanide ion which can be reduced to the divalent state or when the ligand is bound to one of the tetravalent ions (J0rgensen, 1970). Such transitions are commonly observed in the spectra of complexes of samarium(III), euro-pium(III), thulium(III), ytterbium(III), and cerium(IV). The position of these bands in the spectrum is markedly dependent on the ligand and the metal ion. For example, in the ions RCU the charge transfer bands for europium(III),... 

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