ScI3 Research Articles

Nonchelated Phosphoniomethylidene Complexes of Scandium and Lutetium.

The first phosphoniomethylidene complexes of scandium and lutetium, [LLn(CHPPh3)X] (L = [MeC(NDIPP)CHC(NDIPP)Me]-; Ln = Sc, X = Me, I, TfO; Ln = Lu, X = CH2SiMe3), have been synthesized and fully characterized. DFT calculations clearly demonstrate the presence of an allylic Ln, C, P π-type interaction in these complexes. X-ray diffraction indicates that the scandium iodide complex has the shortest Sc-C bond length to date (2.044(5) Å). These phosphoniomethylidene complexes readily convert into the ylide complexes, and the reactivity is affected by both X- anion and Ln3+ ion. The reaction of lutetium complex with imine shows a rapid insertion of imine into the Lu-C(alkylidene) bond. DFT calculations indicate that, although the bonding situation seems similar to that of the scandium analog, the strong negative charge at the alkylidene carbon is not sufficiently screened by one hydrogen in the lutetium complex because of a more ionic bonding, and therefore, the reactivity of the lutetium complex is much higher.

Synthesis, structure and reactivity of scandium bis(trimethylsilyl)amido derivatives

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R=Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac=(2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.

The structure of the scandium iodide complex with antipyrine (AP) and its comparison with the structure of nonisostructural analogues (Compounds [Ln(AP)6]I3 (Ln = La, Y, or Eu))

An X-ray diffraction study of the scandium iodide complex with antipyrine [Sc(AP)6]I3 (AP is antipyrine, i.e., 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) (I), which is not isostructural to the analogous compounds of Y, La, and Eu (II), is performed. Crystals I are trigonal; a = 24.911 A and c = 10.140 A; Z = 3, space group P $$ \bar 3 $$ . Crystal I is built of [Sc(AP)6]3+ complex cations of two types and I− anions. In both cations, the Sc atom is octahedrally coordinated by six O atoms of six AP ligands (Sc-O, 2.054–2.078 A). Complexes I differ from II by the absence of π-π stacking interactions between AP molecules, resulting in a supramolecular cation. Complex cations I of both types form combined layers. All I− anions are located in the interlayer space, being statistically disordered within a flat area limited by eight complex cations of Sc1 and Sc2.

Synthesis and structure of complex compounds of lanthanum, europium, and scandium iodides with antipyrine

Synthesis and X-ray single-crystal diffraction study of antipyrine complexes of lanthanum, europium, and scandium iodides were performed. In all compounds, the inner coordination sphere of the complex cation is an octahedron formed by antipyrine molecules coordinated through the oxygen atoms of the C=O groups.

Instruction to Authors

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R = Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.

Instructions to Authors

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R = Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.

Instructions to Authors

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R = Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.

Instructions for Authors

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R = Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.

Scandium iodides without and with carbon

There are two binary iodides of scandium, the rather trivial insulating ScI 3 and the scandium deficient Sc 0.9I 2, metallic above and insulating below about 100 K. At low temperatures, six out of eight excess electrons corresponding to Sc 0.89I 2 × 9 = Sc 8□ 1I 18 = (Sc 3+) 2(Sc 2+) 6(□ 1)(I −) 18 are localized in 3d states, and one regular metal site of a hypothetical CdI 2-like superstructure of ScI 2 is empty. At high temperatures, the electrons delocalize into a conduction band, in accord with the formulation (Sc 3+) 8(□ 1)(e −) 6(I −) 18. Excess electrons may also be added or consumed by a third partner. The first case is realized in the, again, scandium deficient ternary halides ASc x X 3 (A = Rb, Cs; X = Cl, Br, I). These have all, in principle, the CsNiCl 3-type of structure in which halide octahedra share common faces. Their centres are, in accord with, e.g., CsSc 0.75I 3 × 4 = Cs 4Sc 3□ 1I 12 = (Cs +) 4(Sc 3+) 3(□ 1)(e −) 1(I −) 12, occupied in three out of four cases. At sufficiently low temperatures, the one excess electron is localized at the middle scandium atom of a triad of scandium atoms. The scandium carbide iodides Sc 4C 2I 6 and Sc 6C 2I 11 are examples of reduced scandium iodides in which electrons are consumed by carbon dimers which occupy, as interstitials, the centres of scandium metal octahedra. In attempts to reproduce these in pure form, we have obtained Sc 24C 10I 30. It is built of nano-sized Sc 24C 10I 30 molecules which consist of a shell of 30 I − ions, a truncated and hollow T4 supertetrahedron. It envelopes a T3 supertetrahedron of 20 scandium atoms in which the tetrahedral interstices are occupied by carbon atoms. The T2 supertetrahedron C 10 itself incorporates a tetrahedron of scandium atoms. This inner scandium tetrahedron traps two electrons in a four-centre-two-electron molecular orbital. In total, Sc 24C 10I 30 may be viewed as (e −) 2(Sc 3+) 4(C 4−) 10(Sc 3+) 20(I −) 30.

Effects and mechanism of sodium loss in quartz metal halide lamps

Several analytical techniques have been used to obtain a detailed mass balance of a test series of metal halide lamps, containing sodium and scandium iodide. The lamps were made to burn for 5000 h and showed appreciable sodium loss, up to 45% at the end of 5000 h.In burners dosed with an excess of scandium metal the loss of sodium caused an increase in the amount of scandium iodide. Thermodynamic modelling showed that scandium, present as a silicate, is converted into scandium iodide. This implies that the loss of sodium will cause a significant shift in the composition of the salt pool in the burner and this will affect the light technical properties and lifetime determining phenomena. Sodium that has escaped from the arc tube has a certain propensity for being deposited on the metal frame in the outer bulb. Since it is a very effective electron emitter, the emission of electrons by photo- and thermionic emission will be strongly enhanced. It is argued that this must have a significant effect on the sodium loss process and on the interpretation of experiments done in the past to reveal the mechanism of sodium loss. A two-phase model for sodium loss is proposed.

Instructions to Authors

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R = Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.

Synthesis and properties of two novel line phases that contain linear scandium chains, lithium scandium iodide (LiScI3) and sodium scandium iodide (Na0.5ScI3)

The title compounds are produced through reactions of Sc, ScI[sub 3], and LiI or NaI at 750-850C in sealed niobium tubing. The slightly paramagnetic lithium phase has a fixed composition near LiScI[sub 3] judging from Guinier powder data and direct analyses. The structure refined from single-crystal X-ray data (P[bar 6]c2, Z = 2, a = 7.2861 (9) [angstrom], c = 6.768 (2) [angstrom], R/R[sub w] = 0.96/3.2%) contains equally spaced scandium atoms (d(Sc-Sc) = 3.384 (1) [angstrom]) in chains of confacial ScI[sub 6/3] octahedra that lie normal to hcp iodine layers. Lithium in iodine octahedra is ordered so as to define confacial trigonal prisms about each chain. The sodium phase has a fixed composition close to Na[sub 0.5]ScI[sub 3] according to the same criteria as well as the structural refinement (Na[sub 0.53(2)]ScI[sub 3]: P31c, Z = 4, a = 7.492 (2), c = 13.699 (3) [angstrom], R/R[sub W] = 2.2/3.2% for data to 2[theta] = 60[degree]). The scandium atoms are paired within slightly distorted chains of confacial octahedra normal to hcp iodine layers (d(Sc-Sc) = 3.278 (5), 3.572 (5) [angstrom]). Sodium at [approximately]50% occupancy within iodine octahedra presents a novel arrangement, trigonal prisms centered around each dimer that are alternatelymore » rotated by [approximately]60[degree] along the chain. The phase exhibits a small, temperature-independent paramagnetism. The results are compared with those for other nominal d[sup 1] trihalides.« less

The layered, metallic scandium iodide Sc0.93I2: synthesis, structure, and properties

The stoichiometry of the layered metallic scandium iodide Sc{sub 0.93}I{sub 2}, reported earlier is confirmed. The compound was prepared by the reaction of ScI{sub 3} with excess metal over a sizeable temperature range; however, the composition was not detectably temperature dependent. Several properties of the material were measured, and the results are reported. The results of studies of the synthesis to clarify the structure through vapor-phase transport as well as Guinier powder and single crystal x-ray diffraction are reported. 21 refs., 2 tabs.

Two scandium iodide carbides containing dicarbon units within scandium clusters: Sc6I11C2 and Sc4I6C2. Synthesis, structure, and the bonding of dicarbon

Sc 6 I 11 C 2 et Sc 4 I 6 C 2 cristallisent dans le systeme triclinique, groupe d'espace P1 et leur structure est affinee respectivement jusqu'a R=0,040 et R=0,085

A radiation and convection model of the vertical mercury arc containing sodium and scandium iodides

A model has been developed for a multicomponent gas discharge containing several radiative species, Hg, I, Na, Sc, Sc+, and ScI, subject to radial and axial segregation. Net emission coefficients for self-absorbed radiation from these species are deduced individually and collectively from experiment and imprisonment theory. The vertical arc convection model has been modified to take into account the axial variation of material parameters with segregation and to calculate quartz wall temperatures. Calculated lamp parameters are found to be in reasonable agreement with experimental data.