Thulium complexes

Figure 11.29 Square symbols-the EL spectrum of the device ITO/PVK/Tmcomplex/Al at drive voltage 10 V solid line - the PL spectrum of the Tm(ACAC)3(phen) powder (excitation wavelength 350 nm) [65]. (Reproduced from Synthetic Metals, 104, Z.R. Hong et al., Spectrally-narrow blue light-emitting organic electroluminescent devices utihzing thulium complexes, 165-168, 1999, with permission from Elsevier.)...

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. 

Di-rerr-butylsodium pyrrolate serves as a source of the complexes of lanthanides [93CB2657 95JOM(495)C12]. Thus, with cyclooctadienyl chlorides of samarium, thulium, and lutetium, it affords species 89 [96JOM(507)287]. The N-coordinated samarium(II) calix-pyrrole complex is known [99AG(E)1432]. 

In 2000, most European countries switched from their traditional currencies to the euro. Lanthanide luminescence is used as a means of preventing counterfeit euro banknotes from passing into the money chain. Excitation of euro banknotes with ultraviolet light results in fluorescence in the red, green and blue regions due to complexes of europium (Eu3+), terbium (Tb3+) and thulium (Tm3+), respectively, that are present in the banknotes. 

The influence of steric factors was thoroughly studied in the reaction of Ln(btsa)3 with the alcohol tritox-H. While the reaction takes place with larger lanthanides like neodymium to yield the homoleptic alkoxide complexes (Eq. 18) [264], the analogous reaction does not work with smaller metals like yttrium and thulium (Eq. 19). However, variation of the reaction conditions to a stoichiometric solid reaction yielded a fully exchanged product along with an unexpected and unusual silylamine degradation [265] (Eq. 20). This degradation reaction seems to be sterically forced and points out N-Si bond disruptions and C-Si bond formations under mild conditions [114]. 

The mixed alkoxide/aryloxide complex (tritox)3Ce(OC6H40)Ce(tritox)3 was obtained by reaction of Ce(tritox)3 with benzoquinone [54], Its molecular arrangement resembles that in the pseudomononuclear thulium tritox complex discussed earlier. 

Thulium(II) complexes are stabilized by phospholyl or arsolyl ligands that can be regarded as derived from the cyclopentadienyl group by replacing one CH group by a P or As atom. Their decreased n-donor capacity relative to the parent cyclopentadienyl system enhances the stability of the Tm(II) center, and stable complexes of the bent-sandwiched type have been isolated. 

The position of yttrium in rare earth chemistry has always been interesting and this is also the case with respect to complex formation. The electrostatic model suggests placement of yttrium between holmium and thulium. It has been shown that it is not the case [14]. When one considers the stability constant data of group 1 ligands, yttrium is similar to the heavy rare earths. When the second group of ligands is considered, yttrium exhibits a behaviour similar to the lighter rare earth elements. 

The behaviour of lanthanum in dimethyl formamide (DMF) is quite different from that in methanol and acetonitrile. While perchlorate forms inner sphere complexes with lanthanides in acetonitrile [31], no such complexes are formed in DMF [32]. The coordination properties in DMF solutions were studied by NMR and UV-Vis spectroscopy techniques [33,34], The rate of DMF exchange in the system ytterbium perchlorate-DMF-CD2CI2 was slow enough that 1H NMR resonances permitted the determination of the mean coordination number to be 7.8 0.2. Similar determination in the case of thulium(III) gave a mean coordination number of 7.7 0.2. Thus it was concluded that the predominant species in heavy lanthanides is Ln(DMF)g+ in DMF solutions. In the case of lighter lanthanides, the following equilibrium exists... 

The only complexes of lanthanum or cerium to be described are [La(terpy)3][C104]3 175) and Ce(terpy)Cl3 H20 411). The lanthanum compound is a 1 3 electrolyte in MeCN or MeN02, and is almost certainly a nine-coordinate mononuclear species the structure of the cerium compound is not known with any certainty. A number of workers have reported hydrated 1 1 complexes of terpy with praseodymium chloride 376,411,438), and the complex PrCl3(terpy)-8H20 has been structurally characterized 376). The metal is in nine-coordinate monocapped square-antiprismatic [Pr(terpy)Cl(H20)5] cations (Fig. 24). Complexes with a 1 1 stoichiometry have also been described for neodymium 33, 409, 411, 413, 417), samarium 33, 411, 412), europium 33, 316, 411, 414, 417), gadolinium 33, 411), terbium 316, 410, 414), dysprosium 33, 410, 412), holmium 33, 410), erbium 33, 410, 417), thulium 410, 412), and ytterbium 410). The 1 2 stoichiometry has only been observed with the later lanthanides, europium 33, 411, 414), gadolinium, dysprosium, and erbium 33). 

Patel V. M. and Joshi J. D., Equilibrium study on the complex formation of europium-, terbium-, dysprosium- and thulium (III) with some oxyacids, thioacids and phenols. J. Indian Chem. Soc. 75 (1998) pp. 100-101. 

Notice that Moseley had made a minor mistake in the atomic number determinations of both holmium and dysprosium. The atomic number of holmium is namely 67, and dysprosium has an atomic number of 66. It also appears that Moseley attached some credence to the investigation of Auer von Welsbach who had demonstrated the complexity of thulium in 1911 by splitting it into three components. Moseley had incorporated two of these components (Tml and Tmll) in his atomic number sequence. Moseley therefore ascribed Urbain s neo-ytterbium and lutetium too high an atomic number (in reality the atomic numbers of ytterbium and... 

Lanthanide elements (referred to as Ln) have atomic numbers that range from 57 to 71. They are lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). With the inclusion of scandium (Sc) and yttrium (Y), which are in the same subgroup, this total of 17 elements are referred to as the rare earth elements (RE). They are similar in some aspects but very different in many others. Based on the electronic configuration of the rare earth elements, in this chapter we will discuss the lanthanide contraction phenomenon and the consequential effects on the chemical and physical properties of these elements. The coordination chemistry of lanthanide complexes containing small inorganic ligands is also briefly introduced here [1-5]. 

Bochkarev, M.N., Fedushkin, I.L., Fagin, A.A. et al. (1997) Synthesis and structure of the first molecular thulium(II) complex [Tml2(MeOCH2CH2CH20Me)3]. Angewattiite Chemie International Edition, 36, 133. 

The thulium (III) ion exhibits spectrally narrow light emission at about 480 nm. Li and coworkers were the first to use the Tm + ion in OLEDs [65]. They prepared a Tm complex Tm(acac)3(phen) and constructed double-layer cells with structure ITO/PVK/Tm complex/Al. The electroluminescence spectrum of the OLED with drive voltage 10 V and the photoluminescence spectrum with excitation wavelength at 350 nm are shown in Figure 11.29. The emitting intensity of 6.0cdm was achieved when a 16 V forward bias voltage was applied. 

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