No abstract

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) 3 Ln(SPh) 3 ] 2 (Ln ) Ho (1) and Tm (2)), [(py) 2 Sm(SPh) 3 ] 4 (3), [(THF)Sm(SPh) 3 ] 4n (4), (THF) 3 Ln(SePh) 3 (Ln ) Tm (5), Ho (6), Er (7)), [(py) 3 Sm(SePh) 3 ] 2 (8), and [(THF) 4 Ln 3 -(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. Compounds 5-7 are molecular fac-octahedral complexes, compounds 1, 2, and 8 are bimetallic molecules with a pair of chalcogen atoms spanning the pentagonal bipyramidal metal centers, compound 3 is a tetrametallic structure with an alternating (3-2-3) number of µ 2 -thiolates spanning the linear assembly of four seven-coordinate Sm(III) ions, and compounds 4, 9, 10, and 11 are polymers with sets of three doubly bridging benzenechalcogenolates connecting adjacent metal ions. Resonance Raman spectroscopy indicates that the intense electronic absorption associated with Sm(III) chalcogenolate is a chalcogen-to-metal charge-transfer excitation. Compounds 1 and 2 decompose thermally to give Ln 2 S 3 .

Europium-mercury amalgam reacts with diphenyl disulfide in THF to give a heterometallic product that crystallizes from pyridine (py) as [(py)3Eu(ti2-SPh)2(ti3-SPh)Hg(SPh)]2'2py (1). Cluster 1 reacts with Cd in pyridine to give [(py)3Eu(M2-SPh)2(M3-SPh)Cd(SPh)]2-2py (2) and with Zn in THF to give [(THF)3Eu(w2-SPh)2(w3-SPh)Zn(SPh)]2• THF (3). All three compounds have been characterized by NMR, IR, and UV-visible spectroscopy and by single-crystal X-ray diffraction. The three are structurally related; 1 and 2 are isostructural tetrametallic clusters with µ2 and µ3 thiolate ligands connecting the 7-coordinate Eu(II) and tetrahedral group 12 metal ions. The lanthanide coordination sphere is saturated with three neutral pyridine donors, and the group 12 metal ion is bound to a terminal benzenethiolate ligand. The zinc cluster 3 has the same tetrametallic framework and connectivity as 1 and 2 but crystallizes in a different unit cell. The thermolysis products of these compounds have been established: 1 decomposes to give EuS, Ph2S, Hg, and S2Ph2; 2 eliminates Ph2S to give a mixture of CdS and EuS; 3 eliminates Ph2S to give a mixture of EuS and ZnS. Crystal data for 1-3 (Mo Ka radiation,

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 P1̄, a = 10.582(3) Å, b = 12.114(2) Å, c = 18.946(6) Å, α = 89.57(2)°, β = 86.11(4)°, γ = 75.87(2)°, V = 2350(1)Å3, Z = 2; 2, monoclinic space group P21/c, a = 12.961(2) Å, b = 22.768(4) Å, c = 22.560(4) Å, β = 95.04(2)°, V = 6632(2) Å3, Z = 4; 3, monoclinic space group Cc, a = 20.737(6) Å, b = 9.801(3) Å, c = 18.849(5) Å, β = 125.34(2)°, V = 3125(2) Å3, Z = 4.

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.