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A series of dimeric thorium disulfides and diselenides have been prepared with sterically undemanding ancillary ligands. Five complexes, (py)6Th2I4(μ2-S2)2, (py)6Th2Br2(SC6F5)2(μ2-S2)2, (py)6Th2I4(μ2-Se2)2, (py)6Th2I2(SC6F5)2(μ2-Se2)2, and (py)6Th2Br2(SC6F5)2(μ2-Se2)2, were isolated in high yields by first reducing mixtures of I2, F5C6SSC6F5, PhSeSePh, or PhSSPh, and PhSeBr with elemental Th, followed by in situ ligand-based redox reactions with elemental sulfur or selenium. These are the first examples of thorium compounds with bridging dichalcogenide ligands. Attempts to prepare chloride derivatives gave mixtures of (py)4ThCl4 and either (py)6Th2Cl2(SC6F5)2(μ2-S2)2 or (py)8Th4Se4(SePh)4(SC6F5)4. All products were characterized by single-crystal and powder X-ray diffraction and IR, UV–visible, and NMR spectroscopy. A computational analysis of experimental 77Se NMR chemical shifts reveals that the solvated dimeric structures with two bridging dichalcogenides are maintained in solution. Thermolysis of (py)...

Thorium cubanes (py)8Th4(μ3-E′)4(μ2-EPh)4(η-EPh)4 (E, E′ = S, Se) were prepared from ligand-based redox reactions of elemental E′ with Th(EPh)4. Products with all four possible E/E′ combinations (E,E′ = S,S; Se,Se; S,Se; Se,S) were isolated and structurally characterized, ligand exchange reactions were explored, and the heterochalcogen compounds (py)8Th4(μ3-S)4(μ2-SePh)4(η-SePh)4 and (py)8Th4(μ3-Se)4(μ2-SPh)4(η-SPh)4 were heated to deliver solid solutions of ThSxSe2–x. NMR spectroscopy indicated that the structure of (py)8Th4(μ3-Se)4(μ2-SePh)4(η-SePh)4 is static in pyridine solution, with no exchange between bridging and terminal PhE– ligands on the NMR time scale. A computational analysis of 77Se NMR shifts provides insight into the solution structure of both clusters and monomeric chalcogenolates.

(DME)2Ln(SeC6F5)3 (Ln = Nd, Er, Tm) can be isolated in high yield by reductive cleavage of the Se-Se bond in (SeC6F5)2 with elemental Ln in DME. All three Ln compounds are isostructural, with 8 coordinate Ln bound to four O from DME, three terminally bound Se(C6F5), and a dative bond from an arene fluoride to a fluorine at the ortho position of one selenolate. Emission measurements indicate that these compounds are bright NIR sources.

Tetrametallic thorium compounds with a Th4E4 core (E = S, Se) having a distorted cubane structure can be prepared by ligand-based reductions of elemental E with thorium chalcogenolates, prepared by in situ oxidation of Th metal with a 3:1 mixture of PhEEPh and F5C6EEC6F5. Four compounds, (py)8Th4S4(μ2-SPh)4(SC6F5)4, (py)8Th4S4(μ2-SPh)4(SeC6F5)4, (py)8Th4Se4(μ2-SePh)4(SeC6F5)4, and (py)8Th4Se4(μ2-SePh)4(SC6F5)4, were isolated and characterized by NMR spectroscopy and X-ray diffraction. These compounds clearly demonstrate the chemical impact of ring fluorination, with the less-nucleophilic EC6F5 ligands occupying the terminal binding sites and the EPh ligands bridging two metal centers. For this series of compounds, crystal packing and intermolecular π···π and H-bonding interactions result in a consistent motif and crystallization in a body-centered tetragonal unit cell. Solution-state 77Se NMR spectroscopy reveals that the solid-state structures are maintained in pyridine.

Soluble molecular actinide(iv) fluorides can be prepared in high yield via redox or metathesis reactions of silver fluorides with actinide compounds containing ancillary iodide or fluorinated thiolate ligands. Two compounds, (py)4UF2I2·2py and (py)7Th2F5(SC6F5)3·2py were isolated and characterized by conventional methods, powder and low temperature single crystal X-ray diffraction.

Thorium chalcogenolates Th(ER)4 react with 2,2′-bipyridine (bipy) to form complexes with the stoichiometry (bipy)2Th(ER)4 (E = S, Se; R = Ph, C6F5). All four compounds have been isolated and characterized by spectroscopic methods and low-temperature single crystal X-ray diffraction. Two of the products, (bipy)2Th(SC6F5)4 and (bipy)2Th(SeC6F5)4, crystallize with lattice solvent, (bipy)2Th(SPh)4 crystallizes with no lattice solvent, and the selenolate (bipy)2Th(SePh)4 crystallizes in two phases, with and without lattice solvent. In all four compounds the available volume for coordination bounded by the two bipy ligands is large enough to allow significant conformational flexibility of thiolate or selenolate ligands. 77Se NMR confirms that the structures of the selenolate products are the same in pyridine solution and in the solid state. Attempts to prepare analogous derivatives with 2,2′,6′,2′′-terpyridine (terpy) were successful only in the isolation of (terpy)(py)Th(SPh)4, the first terpy compound of thorium. These materials are thermochromic, with color attributed to ligand-to-ligand charge transfer excitations.

This review surveys the chemistry and extraordinary NIR spectroscopy of molecules and clusters with bonds between Lanthanide ions and the group 16 elements Sulfur and Selenium.

Thorium chalcogenolates Th(ER)4 (E = S, Se; R = Ph, C6F5) form pyridine complexes with a variety of coordination numbers. Four compounds, (py)4Th(SPh)4, (py)3Th(SePh)4, (py)3Th(SC6F5)4, and (py)4Th(SeC6F5)4, have been isolated and characterized by spectroscopic methods and low-temperature single crystal X-ray diffraction. Two of the products, (py)4Th(SPh)4 and (py)4Th(SeC6F5)4, have classic eight coordinate A4B4 square-antiprism geometries. The SePh compound is the only seven coordinate (4Se, 3N) product, and the fluorinated thiolate is distinctive in that the structure contains two dative interactions between Th and fluoride, to give a nine coordinate (3N, 4S, 2F) structure. The EPh compounds decompose thermally to give ThE2 and EPh2, while the fluorinated compounds give primarily ThF4, E2(C6F5)2, and E(C6F5)2.

Reductive cleavage of C(6)F(5)SeSeC(6)F(5) with elemental M (M = Zn, Cd, and Hg) in pyridine results in the formation of (py)(2)Zn(SeC(6)F(5))(2), (py)(2)Cd(SeC(6)F(5))(2), and Hg(SeC(6)F(5))(2). Structural characterization of the Zn and Cd compounds reveals tetrahedral coordination environments, while the Hg compound shows a complicated series of linear structures with two short, nearly linear Hg-Se bonds, up to two longer and perpendicular Hg...Se interactions, and no coordinated pyridine ligands. All three compounds exhibit well-defined intermolecular pi-pi-stacking interactions in the solid state. They are volatile and decompose at elevated temperatures to give MSe and either (SeC(6)F(5))(2) or Se(C(6)F(5))(2).

"Ln(TePh)(3)" (Ln = Er, Tm, Lu), prepared in situ by the reduction of PhTeTePh with elemental Ln in the presence of Hg catalyst, reacts with elemental Te to give heterometallic clusters with the formula (py)(7)Ln(3)HgTe(4)(TePh)(3). Structural characterization of all three isostructural derivatives reveals a cubane arrangement of metal ions, with a distorted tetrahedral Hg(II) ion coordinated to three mu(3) coordinate Te(2-) and a terminal TePh ligand. There are two chemically inequivalent types of octahedral Ln(III) ions, one bound to three Te(2-) and three pyridine donors, and two that coordinate two pyridine, three Te(2-), and a terminal TePh ligand. The Lu compound decomposes at elevated temperatures to give LuTe.

Molecular (DME)2Tm(SC6F5)3 and tetrametallic (DME)4(µ2-SPh)8Tm4(SPh)4 have been isolated in high yield and characterized by conventional methods. The fluorinated thiolate has an eight-coordinate Tm(III) ion bound to three sulfur atoms from the thiolates, four oxygen donors from the THF ligands, and a relatively weak dative Tm-F interaction with a 2.842(3)A Tm-F separation. The benzenethiolate compound crystallizes as a tetramer with an alternating number (3, 2, 3) of thiolates connecting the nearly linear array of Tm(III) ions. Emission properties of both thiolates and the chalcogen-rich cluster (THF)6Tm4Se9(SC6F5)2 have been established. The Ph compound is significantly more emissive than either of the fluorinated species.

Reductive cleavage of C6F5SeSeC6F5 with elemental M (M = Cu, In, Sn, Pb) in pyridine results in the formation of (py)4Cu2(SeC6F5)2, (py)2In(SeC6F5)3, (py)2Sn(SeC6F5)2, and (py)2Pb(SeC6F5)2. Each group adopts a unique structure: the Cu(I) compound crystallizes as a dimer with a pair of bridging selenolates, two pyridine ligands coordinating to each Cu(I) ion, and a short Cu(I)-Cu(I) distance (2.595 A). The indium compound crystallizes as monometallic five-coordinate (py)2In(SeC6F5)3 in a geometry that approximates a trigonal bipyramidal structure with two axial pyridine ligands and three selenolates. The tin and lead derivatives (py)2M(SeC6F5)2 are also monomeric, but they adopt nearly octahedral geometries with trans pyridine ligands, a pair of cis-selenolates, and two "empty" cis-positions on the octahedron that are oriented toward extremely remote selenolates (M-Se = 3.79 A (Sn), 3.70 A (Pb)) from adjacent molecules. Two of the four compounds (Cu, In) exhibit intermolecular π-π stacking arrangements in the solid state, whereas the stacking of molecules for the other two compounds (Sn, Pb) appears to be based upon molecular shape and crystal packing forces. All compounds are volatile and decompose at elevated temperatures to give MSex and Se(C6F5)2.The electronic structures of the dimeric Cu compound and monomeric (py)2M(SeC6F5)2 (M = Sn, Pb) were examined with density functional theory calculations.

The photoluminescent properties of the nanoscale rare earth ceramic clusters (THF) 14 Er 10 S 6 Se 12 I 6 (THF = tetrahydrofuran), (THF) 8 Nd 8 O 2 Se 2 (SePh) 16 , and the molecular thiolates (DME) 2 X(SC 6 F 5 ) 3 (DME = 1,2-dimethoxyethane, X = Er or Nd) are studied by optical absorption and photoluminescence. From the Judd–Ofelt (JO) analysis of the absorption spectra and the measured decay time of the photoemission it is found that the Er complexes show high quantum efficiencies whereas the Nd complexes not. The differences are explained in terms of energy transfer processes among the corresponding active ions. It is found that the Nd thiolate present the most drastic quenching in spite that the energy transfer processes are driven only by multipolar interactions whereas for the other complexes, there is evidence of migration for the Nd one and upconversion for the Er complex.

Reactions of "LnI(x)(SePh)(3-x)" (Ln = Dy, Ho) with elemental S/Se give (THF)14Ln10S6(Se2)6I6. The compounds are composed of a Ln6S6 double cubane core, with two twisted "Ln2(SeSe)3" units condensed onto opposing rectangular sides of the Ln6S6 fragment. This deposition of Ln2Se6 totally encapsulates the two central Ln's with chalcogen atoms (four S and four Se atoms), excluding neutral THF donors or iodides from the two primary coordination spheres. Reactions of Ln(10) clusters with a stronger Lewis base result in fragmentation and, in the case of Ln = Er, the isolation of (py)6Er2(Se2)(S0.8Se0.2)I2, with two Ln(III) ions spanned by E2- and (EE)2- ligands. The related homochalcogen dimers (py)6Ln2(Se2)(Se)Br2 (Ln = Ho, Yb) were prepared to establish that such molecules could be prepared rationally, and to confirm the isolability of E2- ligands coordinated to only two sterically unconstrained Ln ions.

Mixtures of Ln(SC(6)F(5))(3) and Ln(EPh)(3) (E = S, Se) react with elemental E to give chalcogen-rich clusters with fluorinated thiolate ancillary ligands. The structures of both (THF)(6)Yb(4)S(SS)(4)(SC(6)F(5))(2) and (THF)(6)Yb(4)Se(SeSe)(4)(SC(6)F(5))(2) have been established by low-temperature single-crystal X-ray diffraction. Both compounds contain a square array of Yb(III) ions connected by a central mu(4)-E(2-) ligand. The edges of the square Yb(4) array are bridged by four mu(2)(EE) ligands, and two terminal SC(6)F(5) are on the same side of the Ln(4) plane that is capped by the mu(4)-E(2-) ion. Redox inactive (THF)(6)Tm(4)Se(SeSe)(4)(SC(6)F(5))(2) was also prepared to establish the extension of this chemistry to the redox inactive Ln. These clusters are soluble in toluene.

Lanthanide metals react with PhTeTePh and elemental Te in pyridine to give (py)yLn4(Te)(TeTe)2(TeTeTe(Ph)TeTe)(TexTePh) (Ln = Sm (y = 9; x = 0); Tb, Ho (y = 8, x = 0.1)), and (py)7Tm4(Te)[(TeTe)4TePh](Te0.6TePh) clusters. The Sm, Tb, and Ho compounds contain a square array of Ln(III) ions all connected to a central Te2- ligand. Two adjacent edges of the square are bridged by ditelluride ligands, with the Ln ion that is η2 bound to both of these TeTe ligands also coordinating to a terminal TePh ligand. The other two edges of the square are spanned by ditellurides that both coordinate a TePh ligand that has been displaced from the Ln ion by pyridine, to give the pentaanion (μ-η2-η2-Te2Te(Ph)Te2).5- In the Tm compound, the displaced TePh interacts with all four TeTe units. The compounds are air-, light-, and temperature-sensitive. Upon thermolysis, they decompose to give solid-state TbTe2-x, HoTe, or TmTe, with elimination of Te and TePh2.

Lanthanides reduce mixtures of I(2) and PhSeSePh in THF, and the resultant heteroligand mixture reacts further with elemental Se in pyridine to give (THF)(6)Ln(4)I(2)(SeSe)(4)(mu(4)-Se).THF (Ln = Tm, Ho, Er, Yb). These selenium rich clusters contain a square array of Ln(III) ions connected through a single (mu(4)-Se) ligand. There are two I(-) ligands coordinating nonadjacent Ln(III) ions on the side of the cluster opposite the (mu(4)-Se), and the edges of the square are bridged by mu(2)-SeSe groups. The electronic spectrum of the Yb compound contains two absorption maxima that can tentatively be assigned as Se(2-) to Yb and SeSe to Yb charge-transfer absorptions, by comparison with the featureless absorption spectra of the Tm, Ho, and Er derivatives. With a 1/1/1/1 Yb/I/Ph(2)S(2)/Se stoichiometry, chalcogen rich compounds are not obtained, but instead, in Yb chemistry, the selenido cluster (THF)(10)Yb(6)Se(6)I(6) can be isolated in 51% yield. The molecular structure of this compound contains a Yb(4)Se(4) cubane fragment, with an additional Yb(2)Se(2) layer capping one face of the cube. Each Yb coordinates a terminal I(-). This intensely colored compound also has an absorption maximum in the visible spectrum. Upon thermolysis, the selenium rich compounds give Ln(2)Se(3) that is free of iodide contamination.

Fluorinated thiolates form particularly stable chalcogenolate complexes with the lanthanides. Both Sm(SC6F5)3 and Eu(SC6F5)2 were prepared by transmetalation. The Sm compound is a dimer in the solid state, with a pair of bridging thiolate ligands connecting the two Sm(III) ions, while the Eu(II) compound is polymeric. In both compounds there are clearly defined Ln−F interactions. Thermolysis of the Sm compound gives SmF3 and (C6F4S)n (n = 2, 3, 4).

Crystalline coordination complexes of Sm(EPh)2 (E = Se, Te) are described. The selenolate compound Sm(SePh)2 is unstable in solution, but a divalent selenolate can be prepared and isolated when precisely 1 equiv of Zn(SePh)2 is present to form heterometallic [(THF)3Sm(mu 2-SePh)3Zn(mu 2-SePh)]n (1). This compound is a 1D coordination polymer with alternating Sm(II) and Zn(II) ions connected by an alternating (1,3) number of bridging selenolate ligands and three THF ligands bound to each Sm(II) ion. The tellurolate Sm(TePh)2 forms a stable pyridine coordination compound (py)5Sm(TePh)2 (2) that is isostructural with known Eu and Yb benzenetellurolates. Both compounds were characterized by conventional spectroscopic methods. Polymer 1 was characterized by low-temperature single-crystal X-ray diffraction, and the unit cell of the tellurolate was determined. Crystal data (Mo K alpha, 153(5) (K) are as follows. 1: monoclinic space group P21, a = 10.666(2) A, b = 16.270(3) A, c = 12.002(3) A, beta = 114.81(2) degrees, Z = 2.2: orthorhombic space group Pbca, with a = 13.865(3) A, b = 16.453(5) A, c = 31.952(7) A, Z = 8.

Octametallic (L)(8)Ln(8)E(6)(EPh)(12) clusters (L = Lewis base; Ln = lanthanide ion; E = S, Se; EPh = SPh, SePh) can be prepared either by the reduction of Se-C bonds with low-valent Ln or by the reaction of Ln(SePh)(3) with elemental E. Because all possible ligand sites (i.e., L, E, EPh) are reactive, the ligands can be varied systematically to further the understanding of structure/property relationships. Chalcogenolate ligands can be selectively varied, as in the reaction of (THF)(8)Sm(8)Se(6)(SePh)(12) with PhSSPh to form (THF)(8)Sm(8)Se(6)(SPh)(12). Neutral L can be altered without disrupting structure, as in the replacement of THF with pyridine to give (py)(8)Sm(8)Se(6)(SePh)(12). Even chalcogenido ligands can be chemically replaced: the reaction of (THF)(8)Sm(8)Se(6)(SPh)(12) with elemental S gives the all-sulfur cluster (THF)(8)Sm(8)S(6)(SPh)(12). All compounds were isolated and characterized by IR and UV-visible spectroscopy and by low-temperature single-crystal X-ray diffraction to confirm that the structures contain cubes of Ln(III) ions with E(2)(-) capping the faces and EPh bridging the edges of the cube. The Sm(8)Se(6)(EPh)(12) clusters are intensely colored because of a Se(2)(-) to Sm(III) charge transfer absorption, while the sulfido clusters exhibit the light yellow color characteristic of Sm(III) complexes. The light green Nd complex (py)(8)Nd(8)Se(6)(SePh)(12) was isolated from the reaction of Nd(SePh)(3) with Se to confirm that chalcogenolate displacement is general to the redox-inactive lanthanides and that the intense colors of the Sm selenido clusters are related to the redox activity of the Ln. The two pyridine complexes (py)(8)LnSe(6)(SePh)(12) (Ln = Nd, Sm) are isostructural. Crystal data (Mo Kalpha, 153(2) K) are as follows. (THF)(8)Sm(8)Se(6)(SPh)(12): triclinic space group Ponemacr;, a = 17.637(7) Å, b = 18.337(5) Å, c = 20.466(12) Å, alpha = 103.04(4) degrees, beta = 94.71(4) degrees, gamma = 94.28(3) degrees, Z = 2. (py)(8)Sm(8)Se(6)(SePh)(12): monoclinic space group C2/m, a = 18.770(2) Å, b = 28.113(4) Å, c = 16.461(3) Å, beta = 120.65(1) degrees, Z = 2. (THF)(8)Sm(8)S(6)(SePh)(12): orthorhombic space group Pcab, a = 19.803(3) Å, b = 22.446(3) Å, c = 26.072(4) Å, Z = 8.

Octanuclear (THF)(8)Ln(8)S(6)(SPh)(12).xTHF clusters (Ln = lanthanide ion) can be isolated from the reactions of Ln(SPh)(3) with elemental S. Complexes have been isolated successfully for Ln = Ce (1), Pr (2), Nd (3), Sm (5), Gd (6), Tb (7), Dy (8), Ho (9), and Er (10). Only the Ce and Sm compounds are intensely colored, due to a relatively low energy f( )(1)-to-d(1) promotion for 1 and a S(2)(-) to Sm charge transfer absorption for 5. The complexes are all thermally unstable with respect to loss of THF at room temperature. The reaction of Sm(SPh)(3) with S in a THF/DME mixture gives thermally unstable (THF)(8)Ln(8)S(6)(SPh)(12).6DME (4). The analogous pyridine (py) complexes (py)(8)Ln(8)S(6)(SPh)(12).xpy (Ln = Nd (11), Sm (12), Er (13)) were also found to desolvate at room temperature. All compounds have been characterized by conventional methods and by low-temperature single-crystal X-ray diffraction. Complete structural analyses have been obtained for compounds 4, 7, 12, and 13, and the structures of the rest were confirmed by unit cell determinations. In each case, the same basic octanuclear framework, with a cube of metal atoms connected by S(2)(-) ligands capping the faces of the cube, and SPh ligands spanning the edges of the cube, is observed. Differences in the structures originate either in the relative orientation of the Ph moieties or in the number and orientations of the lattice solvent molecules. The Ce cluster is isostructural with (THF)(8)Sm(8)Se(6)(SePh)(12), compounds 2 and 3 are isostructural with the previously reported structure of 6, clusters 5 and 8-10 are isostructural with 7, and cluster 11 is isostructural with 12.

A series of trivalent lanthanide (Ln) benzenechalcogenolate (EPh, E = S, Se) complexes have been prepared and structurally characterized in an attempt to evaluate how metal size, chalcogen, and solvent influence structure and physical properties. The compounds [(py)3Ln(SPh)3]2 (Ln = Ho (1) and Tm (2)), [(py)2Sm(SPh)3]4 (3), [(THF)Sm(SPh)3]4n (4), (THF)3Ln(SePh)3 (Ln = Tm (5), Ho (6), Er (7)), [(py)3Sm(SePh)3]2 (8), and [(THF)4Ln3(SePh)9]n (Ln = Pr (9), Nd (10), and Sm (11)) were isolated and characterized by IR, NMR, and UV−visible spectroscopy. Compounds 2−4, 7, 8, and 10 have also been characterized by low-temperature single-crystal X-ray diffraction. Three trends in structure are clear. First, the tendency to form oligomeric structures is found to increase with the size of the lanthanide ion. Second, thiolates bridge metal ions to form polynuclear structures more effectively than selenolates. Finally, pyridine displaces bridging chalcogenolates to form less extended structures more effectively than THF...

Heterometallic chalcogenolate compounds containing both lanthanide (Ln) and group 14 metals (M; M = Sn, Pb) form a variety of structures that can be understood in the context of relative metal−chalcogen bond strengths. The compounds (THF)2Eu(μ2-SePh)6Pb2 (1), [Yb(THF)6][Sn(SePh)3]2 (2), and [(py)2Eu(2-S-NC5H4)2Sn(2-S-NC5H4)2]n (3) have been prepared, and their structures have been established by low-temperature single-crystal X-ray diffraction. Ln−S bonds are found to be relatively insensitive to the presence of a group 14 metal thiolate, whereas Ln−Se bonds are readily distorted upon coordination to Pb(SePh)2, and cleaved by the addition of the stronger Lewis acid Sn(SePh)2. The stereochemically active lone pair of electrons on the group 14 metal influences structure, as does the identity of the chalcogenolate. All three compounds show no interaction between the Ln ion and the group 14 metal lone pair. Crystal data (1−3 Mo Kα; −80 to −100 °C): 1, triclinic space group P1, a = 10.582(3) A, b = 12.114(2)...

Weakly binding azide ligands have been used as surface caps in the synthesis of lanthanide oxo and selenido clusters. Addition of NaN3 and Na2O to in situ prepared solutions of Ln(SePh)3 in pyridine results in the formation of (py)18Sm6Na2O2(N3)16 or (py)10Ln6O2(N3)12(SePh)2 (Ln = Ho, Er), with the Sm and Er compounds characterized by low temperature single crystal X-ray diffraction. Attempts to prepare chalcogenido derivatives by ligand-based redox reactions using elemental Se were successful in the preparation of (py)10Er6O2(SeSe)2(N3)10, a diselenido cluster having crystallographic disorder due to some site sharing of both SeSe and N3 ligands. These compounds all detonate when heated.

Pyridineselenolate forms stable homoleptic coordination compounds of Sn(II), Sn(IV), and Pb(II). The complexes can be prepared either by metathesis or by insertion of the metal into the Se−Se bond of dipyridyl diselenide, and they are soluble in coordinating solvents such as pyridine. Isolation of the Pb(II) complex from both Pb(0) and Pb(IV) starting materials indicates that the pyridineselenolate ligand cannot stabilize Pb(IV). The compounds all sublime intact and decompose at elevated temperatures: the divalent complexes give MSe (M = Sn, Pb), while the Sn(IV) compound delivers SnSe2. In order to isolate a crystalline Pb compound, the 3-trimethylsilyl-2-pyridineselenolate ligand was prepared. Attachment of the Me3Si functional group increases compound solubility, and leads to the isolation of crystalline Pb(3-Me3Si-2-SeNC5H4)2. The structure of [Sn(2-SeNC5H4)2]2 (1) was determined by single-crystal X-ray diffraction and shown to be a dimer, with one chelating pyridineselenolate per Sn(II) and a pair o...

The compounds [(py){sub 3}Eu({mu}{sub 2}-SePh){sub 2}({mu}{sub 3}-SePh)Hg(SePh)]{sub 2} (1), (THF){sub 4}Eu({mu}{sub 2}-SePh){sub 3}ZnSePh (2), [Sm(THF){sub 7}][Zn{sub 4}({mu}{sub 2}-SePh){sub 6}(SePh){sub 4}] (3), and [Yb(THF){sub 6}][Hg{sub 5}({mu}{sub 2}-SePh){sub 8}(SePh){sub 4}]{center_dot}2THF (4) were prepared and their structures analyzed by X-ray crystallography. Interpretation of the molecular structure for these compounds based on these studies and on UV-visible spectroscopy data is presented. The compounds were found to be quite fluctional in solution.

Reaction of (MeC{sub 5}H{sub 4}){sub 3}UX (X = Cl, MeC{sub 5}H{sub 4}) with t-BuLi affords the tertiary alkyl complex (MeC{sub 5}H{sub 4}){sub 3}U(t-Bu). Despite uranium(IV) generally being the preferred oxidation state in organometallic systems, (MeC{sub 5}H{sub 4}){sub 3}U(t-Bu) reacts with Lewis bases (L = PMe{sub 3}, THF, RCN, RNC) to yield the reduced uranium(III) base adducts (MeC{sub 5}H{sub 4}){sub 3}U(L). Carbon monoxide undergoes migratory insertion into the metal tertiary alkyl bond. The resulting acyl derivative decomposes at 90{degree}C to yield insoluble uranium-containing products and a mixture of tert-butyltoluenes by ring expansion of a methylcyclopentadienyl ligand. Ethylene also undergoes migratory insertion into the metal tertiary alkyl bond. No subsequent insertion of ethylene into the metal carbon bond takes place after the first equivalent has inserted. In marked contrast, reaction of various (MeC{sub 5}H{sub 4}){sub 3}ThX (X = Cl, I, MeC{sub 5}H{sub 4}, O-2,6-Me{sub 2}C{sub 6}H{sub 3}, OTs) compounds with t-BuLi gave intractable materials. However, reaction of the cationic species [(RC{sub 5}H{sub 4}){sub 3}Th](BPh{sub 4}) (R = Me{sub 3}Si, t-Bu) with t-BuLi yields the new thorium hydrides (RC{sub 5}H{sub 4}){sub 3}ThH. 40 refs., 2 figs.

Lanthanide-mercury amalgams react with diphenyl diselenide to form tris(bezeneselenolates) that can be isolated as the crystalline pyridine coordination complexes (pyridine){sub 3}Ln(SePh){sub 3}(Ln=Ho (1), Tm(2), Yb(3)). The structure of 2 was established by low temperature single crystal X-ray diffraction. The complex is dimeric in the solid state, with 7-coordinate metal centers connected by a pair of {mu}2-(benzeneselenolate) ligands. Thermal decomposition of the selenolates gives a variety of solid state metal selenides: 1 gives HoSe, HoSe{sub 2}, and Ph{sub 2}Se; 2 gives Tm{sub 2}Se{sub 3} and Ph{sub 2}Se; 3 gives Yb{sub 2}Se{sub 3} and Ph{sub 2}Se. Trivalent thiolates can also be prepared by this amalgam reaction. For comparison, the structure of Yb(SPh){sub 3}(pyridine){sub 3}(4) was also determined-4 is a monomeric meroctahedral compound with inequivalent Yb-S bonds. Both 3 and 4 have an intense visible chalogen-to-ytterbium charge transfer absorption band. Crystal data (Mo K{alpha}, 153(2) K) are as follows. 2: Triclinic space group P1, a = 10.435(2) {Angstrom}, b = 12.748(2) {Angstrom}, c = 14.453(2) {Angstrom}, {alpha} = 69.85(2){degrees}, {beta} = 80.71(2){degrees}, and {gamma} = 69.03(2){degrees}. 4: Triclinic space group P1, a = 9.836(10) {Angstrom}, b = 11.304(14) {Angstrom}, c = 16.202(11) {Angstrom}, {alpha} = 80.70{degrees}, {beta} = 77.91(7){degrees}, and {gamma} = 68.34(9){degrees}.

2,2′-Bipyridine (bipy) forms stable crystalline co-ordination complexes with lithium benzeneselenolate and lithium pyridine-2-selenolate. The compounds are insoluble in aromatic hydrocarbons, slightly soluble in pyridine, and extremely soluble in tetrahydrofuran, from which they can be crystallized in ca. 70% yield. Both complexes have been characterized by elemental analysis, NMR, IR, and single-crystal X-ray diffraction. Compound [{Li(bipy)(SePh)}2]1[space group p21/m, a= 9.493(4), b= 16.866(5), c= 10.112(9), β= 114.53(6)° and Z= 4] is a dimer containing two lithium ions bridged by a pair of symmetric benzeneselenolate ligands, with bidentate bipy ligands bound to each lithium ion. In compound [{Li(bipy)(NC5H4Se-2)}2]2[space group P21/n, a= 10.361(5), b= 13.521(4), c= 11.062(5)A, β= 117.21(4)° and Z= 4] each lithium ion is bound to a bidentate bipy ligand, one bridging selenium atom, and the nitrogen atom from the second bridging pyridine-2-selenolate ligand, thus forming an eight-membered Li–Se–C–N–Li–Se–C–N ring. The analogous lithium thiolates have also been prepared in 70% yield; they are not isostructural with the selenolates.

This article reviews the chemistry and physical properties of molecules and clusters with lanthanide-chalcogen bonds. Keywords: lanthanide; chalcogen; NIR emission; organometallics; thermolysis; bonding

Chalcogenolate complexes of ytterbium can bc prepared via a number of synthetic approaches. The reaction between Yb metal and PhE-EPb (E=S, Se, Te) in liquid ammonia results in the formation of divalent ytterbium chalcogcnolates, which can be isolated as the pyridine coordination complexes (pyridine) 5 Yb(SC 6 H 5 ) 2 (1) (pyridine) 4 Yb(SeC 6 H 5 ) 2 (2), and (pyridine) 5 Yb(TeC 6 Hs) 2 (3). Reaction of YbCl 3 with 3 equiv of NaTePh results in the reduction of the metal and the formation of 3 and dipberiyl ditelluride. The thiolate 1 and selenolate 2 can be prepared by reducing the corresponding dichalcogenide with a ytterbium/mercury amalgam in THF

Ln(SePh)(3) (Ln = Ce, Pr, Nd), prepared by reduction of PhSeSePh with elemental Ln and Hg catalyst, reacts with excess elemental Se to give (py)(11)Ln(7)Se(21)HgSePh, an ellipsoidal polyselenide cluster. The molecular structure contains two square arrays of eight- or nine-coordinate Ln fused at one edge to form a V shape that is also capped on the concave side by a centrally located nine-coordinate (Se(3))pyLn(Se(3)) and on the convex side by a 2-fold disordered SeHgSePh. The central Ln coordinates to selenido, triselenido, and pyridine ligands, while all other Ln coordinate to selenido, diselenido, triselenido, and pyridine ligands. Thermal treatment of the Pr compound at 650 °C gave Pr(2)Se(3) and Pr(3)Se(4). NIR emission studies of the Nd compound show four transitions from the excited-state (4)F(3/2) ion to (4)I(9/2), (4)I(11/2), (4)I(13/2), and (4)I(15/2) states. The (4)F(3/2) ion to (4)I(11/2) transition (1075 nm emission) exhibited 43% quantum efficiency. This is the highest quantum efficiency reported for a 'molecular' Nd compound and leads a group of selenide-based clusters that has shown extraordinary quantum efficiency. In terms of efficiency and concentration, these compounds compare favorably with solid-state materials.

This review covers the synthesis, characterization, and reaction chemistry of organometallic complexes of Sc, Y and the lanthanides reported in the years 2004 and 2005. For the first time we have included reports of genuine fullerene compounds. Non-molecular carbides and related species are still ex...

Heterobimetallic complexes containing titanocene chloride and trans-platinum dichloride-DMSO functional groups have been prepared by bridging the metal centers with hydroxypyridine ligands, in order to explore the possibility that a chelate effect will enhance DNA-metal binding affinity and chemotherapeutic effectiveness. The structure of trans-PtCl 2 (DMSO)(NC 5 H 4 -2-OTi(C 5 H 5 ) 2 Cl) has been determined; crystals are monoclinic, (Cc).

Lanthanide chalcogenolates react with either TeO(2) in pyridine or py-SO(3) in THF to give oxychalcogenido clusters. The sulfido derivatives (THF)(8)Ln(8)S(2)O(2)(SePh)(16) (Ln = Ce, Nd) are isostructural with previously reported oxoselenido compounds, and must be prepared at low temperatures to avoid the introduction of Se into the sulfide position. Analogous telluride derivatives for the early lanthanides were not obtained, but reactions of in situ prepared Ln(TePh)(3) with elemental Te and TeO(2) gave a complicated heterocluster product, with tetrametallic polytelluride [(py)(7)Ln(4)(mu(4)-Te)(mu(2)-Te(2))(2)(mu-eta(2)-eta(2)-Te(2)Te(Ph)Te(2))(TePh)] co-crystallizing with the oxotellurido compound [(py)(5)Ln(3)(mu(3)-O)(mu(2)-Te(2))(3)(TePh)] (Ln = Ho, Er). An analysis of the thermal decomposition of these compounds did not identify the oxo-containing products, with the sulfide compounds decomposing to give only Ln(3)Se(4) and the telluride compounds forming crystalline LnTe and Te metal.

Ln(OC(6)F(5))(3) form stable, isolable compounds with 1,2-dimethoxyethane (DME). Monomeric (DME)(2)Ln(OC(6)F(5))(3) (Ln = Nd, Er, Tm) adopt seven coordinate structures with two chelating DME and three terminal phenoxide ligands. Both (py)(4)Er(OC(6)F(5))(3) and (THF)(3)Yb(OC(6)F(5))(3) were also prepared and structurally characterized, with the latter being a mer-octahedral compound with bond lengths that are geometry dependent. Emission experiments on crystalline powders of the Nd(III), Tm(III), and Er(III) DME derivatives show that these compounds are highly emissive near-infrared sources.

The fluorinated phenoxide OC6F5 forms the stable Eu(II) and Eu(III) derivatives (DME)2Eu(mu-OC6F5)3Eu(mu-OC6F5)3Eu(DME)2 and (DME)2Eu(OC6F5)3, as well as the heterovalent product (DME)2Eu(mu-OC6F5)3Eu(DME)(OC6F5)2, in redox reactions of Eu with HOC6F5 or in proton-transfer reactions of HOC6F5 with Eu(SPh)2. The divalent complex crystallizes as a trimer with three bridging phenoxides bridging each pair of metals, with the terminal metals coordinating DME and the central metal ion encapsulated totally by O(C6F5) and dative fluoride interactions. The trivalent compound is monomeric with terminal phenoxide ligands and no Eu-F interactions. The heterovalent compound has clearly localized metal valence states and coordination features that mimic the homovalent species with the terminal OC6F5 bound to the Eu(III) ion, three bridging OR ligands spanning the Eu(II) and Eu(III) ions, and dative Eu(II)-F bonds. At elevated temperatures, these compounds decompose to give a mixture of solid-state fluoride phases.

Neodymium tri-iodide reacts with Group 12 metal (M; M = Zn, Cd, Hg) iodides to form heterometallic compounds. These Lewis acidic M cleave Nd-I bonds to give either ionic ([(THF)(5)NdI(2)][MI(3)THF]; M = Zn, Cd) or charge-neutral [(THF)(5)NdI(micro(2)I)HgI(3)] compounds. Differences in structure are interpreted primarily in terms of M-L bond strengths, rather than Nd-L bond strengths. Experiments with Yb indicate that if there is any excess iodide present in these syntheses then the most readily isolated product is a triiodide salt, i.e., [(THF)(5)YbI(2)][I(3)]. In conventional solvents the presence of Lewis acid is not required for iodide displacement-from pyridine, "YbI(3)" crystallizes as [(py)(5)YbI(2)][I]. These compounds are potentially useful as heterometallic sources of lanthanide-doped iodide matrixes, they illustrate the ease with which iodides are displaced from lanthanide coordination spheres, and they underscore the complexity associated with using lanthanide iodides as Lewis acid catalysts.

[(THF)3Sm(SePh)2Zn(SePh)2]n decomposes to give a variety of products, including [(THF)8Sm4Se(SePh)8](2+)[Zn8Se(SePh)16](2-), an ionic cluster that can also be prepared in more than 60% yield by stoichiometric addition of Se to a mixture of Sm(SePh)3 and Zn(SePh)2. The isostructural Nd compound [(THF)8Nd4Se(SePh)8](2+)[Zn8Se(SePh)16](2-) was also prepared by the stoichiometric route to establish the viability of this cluster type with redox-inactive Ln. In addition, the salt [Yb(THF)6](3+)[Fe4Se4(SePh)4](3-) was isolated and structurally characterized. These ionic cluster materials illustrate the difficulties associated with doping Ln ions into covalent metal chalcogenido matrixes.

The fluorinated tris-thiolate compounds Ln(SC(6)F(5))(3) can be isolated as THF, pyridine, or DME coordination complexes. In THF, the larger Ce forms dimeric [(THF)(3)Ce(SC(6)F(5))(3)](2) (1) with bridging thiolate ligands, while the smaller lanthanides (Ln = Ho (2), Er (3)) form monometallic (THF)(3)Ln(SC(6)F(5))(3) compounds. There is a tendency for fluoride to coordinate to Ln throughout the lanthanide series (Ce-Er). The cerium compound 1 contains a pair of bridging thiolates connecting two eight-coordinate Ce(III) ions. Of the two terminal thiolates, only one exhibits a distinct Ce-F bond. In contrast, the Ho derivative (THF)(3)Ho(SC(6)F(5))(3) is a molecular compound in the solid state, with two monodentate thiolates and one thiolate that again coordinates through both S and F atoms. Incorporation of a stronger Lewis base reduces but does not necessarily eliminate the tendency to form Ln-F bonds. Structural characterization of the eight-coordinate (pyridine)(4)Sm(SC(6)F(5))(3) (4) reveals a single, clearly defined Ln-F interaction, while in (pyridine)(4)Yb(SC(6)F(5))(3) (5) there are no Yb-F bonds. In the structure of (DME)(2)Er(SC(6)F(5))(3) (6) the DME ligands completely displace F from the Er coordination sphere.

The early and late lanthanides form stable complexes with the pyridinethiolate (2-S-NC(5)H(4), or SPy) ligands. The Ce compound Ce(SPy)(3) is relatively insoluble in neutral organic donor solvents such as THF or pyridine but can be solubilized by the addition of [PEt(4)][SPy] to form the orange homoleptic cerium thiolate [PEt(4)][Ce(SPy)(4)] (1). Low-temperature structural characterization of 1 showed that the complex is isostructural with the known Eu(III) derivative. Further oxidation of Ce(III) with dipyridyl disulfide does not occur. Molecular 1 is colored due to a low-energy f(1)-to-d(1) promotion. As the size of the lanthanide ion decreases, the solubility of neutral Ln(SPy)(3) appears to increase. Colorless [PEt(4)][Ln(SPy)(4)] (Ln = Ho (2), Tm (3)) can also be isolated by fractional crystallization, and the compounds are isostructural with the Ce and Eu derivatives. The neutral complexes of Ho and Tm are also slightly soluble in acetonitrile and dimethoxyethane and very soluble in pyridine. Both divalent and trivalent Yb complexes of the pyridinethiolate ligand dissolve in and crystallize from pyridine. Divalent Yb(SPy)(2) crystallizes as the pentagonal bipyramidal molecule (py)(3)Yb(SPy)(2) (4). One pyridine nitrogen and the four donor atoms of the two pyridinethiolate ligands are bound in equatorial positions, and two neutral pyridine ligands occupy the axial sites. The Yb(III) compound crystallizes readily from pyridine as molecular 8-coordinate (py)(2)Yb(SPy)(3) (5). Compounds 4 and 5 are intensely colored; 4 has a visible Yb(II)-to-pyridine charge transfer excitation that is virtually identical in energy to the analogous excitation in SmI(2)(py)(4), while 5 has a visible S-to-Yb charge transfer absorption. Crystal data (Mo Kalpha, 153(5) K) are as follows: 1, monoclinic space group P2/n, a = 15.118(6) Å, b = 16.117(4) Å, c = 26.443(7) Å, beta = 90.14(3) degrees, Z = 4; 4, monoclinic space group Cc, a = 10.588(1) Å, b = 16.810(3) Å, c = 14.833(5) Å, beta = 109.12(2) degrees, Z = 4; 5, monoclinic space group P2(1)/n, a = 9.672(2) Å, b = 16.293(4) Å, c = 19.214(3) Å, beta = 101.51(2) degrees, Z = 4.

Lanthanide metals reduce mixtures of azobenzene and PhEEPh (E = Se or Te) in pyridine to give the bimetallic compounds [(py)2Ln(EPh)(PhNNPh)]2 (E = Se, Ln = Ho (1), Er (2), Tm (3), Yb (4); E = Te, Ln = Ho (5), Er (6), Tm (7), Yb (8)). The structures of [(py)2Er(mu-eta 2-eta 2-PhNNPh)(SePh)](2).2py (2) and [(py)2Ho(mu-eta 2-eta 2-PhNNPh)(TePh)](2).2py (5) have been determined by low-temperature single-crystal X-ray diffraction, and the nearly identical unit cell volumes of the remaining compounds indicate they are most likely isomorphous to 2 or 5. In all compounds, the Ln(III) ions are bridged by a pair of mu-eta 2-eta 2-PhNNPh ligands that, from the N-N bond length, have clearly been reduced to dianions. Charge is balanced by the single terminal EPh ligand on each Ln, and the coordination sphere is saturated by two pyridine donors to give seven coordinate metal centers. Thermal decomposition of 5 gives HoTe, 8 gives a mixture of YbN and YbTe, and 1 does not give a crystalline solid-state product. Crystal data (Mo K alpha, 153(2) K) are as follows: 2, monoclinic group P2(1)/n, a = 11.864(3) A, b = 14.188(2) A, c = 17.624(2) A, beta = 91.62(2) degrees, V = 2965(1) A3, Z = 4; 5, triclinic space group P1, a = 10.349(2) A, b = 17.662(4) A, c = 17.730(8) A, alpha = 75.82(3) degrees, beta = 74.11(3) degrees, gamma = 89.45(2) degrees, V = 3016(2) A3, Z = 2.

This review covers the synthesis, characterization, and reaction chemistry of organometallic complexes of Sc, Y and the lanthanides reported in the years 2004 and 2005. For the first time we have included reports of genuine fullerene compounds. Non-molecular carbides and related species are still ex...

The pyridineselenolate (2-Se-NC(5)H(4), (SePy)) and the 3-(trimethylsilyl)pyridineselenolate (3-Me(3)Si-2-Se-NC(5)H(4) (SePy)) ligands form air-stable homoleptic coordination compounds of Cu(I) { [Cu(SePy)](4) (1) and [Cu(SePy)](4) (2)} and In(III) {In(SePy)(3) (3) and In(SePy)(3) (4)}. Mass spectroscopic characterization of the Cu(I) compounds indicated a tetrametallic core, and this was confirmed with a single-crystal X-ray structural characterization of crystalline 1 and 2, which both contain a tetrametallic cluster of Cu(I) ions bound to two doubly bridging Se atoms and a pyridine nitrogen. The Cu coordination sphere is completed with two strong Cu-Cu bonds and one weaker Cu-Cu interaction. The indium compounds 3 and 4 are each distorted fac-octahedral molecules with chelating SePy ligands. These compounds are useful low-temperature precursors to the binary selenides. Both 3 and 4 sublime intact; 3 thermally decomposes to give In(2)Se(3). The Cu clusters do not sublime intact but still decompose to give metal selenide phases: 2 decomposes to give pure alpha-CuSe at low temperatures and increasing amounts of Cu(2)(-)(x)()Se at elevated temperatures, while 3 decomposes to give a mixture of CuSe phases at all temperatures. Crystal data (Mo Kalpha: 1, 153(5) K; 2-4, 293(2) K) are as follows: 1, monoclinic space group C2/c, a = 20.643(5) Å, b = 16.967(2) Å, c = 16.025(2) Å, beta = 114.16(2) degrees, Z = 8; 2, tetragonal space group I4(1)/a, a = 14.756(3) Å, c = 19.925(3) Å, Z = 4; 3, trigonal space group Pthremacr;c1, a = 13.352(2) Å, c = 13.526(2) Å, Z = 4; 4, monoclinic space group P2(1)/c, a = 9.793(1) Å, b = 20.828(6) Å, c = 16.505(1) Å, beta = 96.69(1) degrees, Z = 4.