Preparation, Structures, and Thermal Decomposition Reactions of Complexes Consisting of TlI, PbII, and SeII and 2,2‐Dicyanoethylene‐1,1‐diselenolate
The 2,2‐dicyanoethylene‐1,1‐diselenolate‐containing compounds (AsPh4)2[Tl2(Se2C=C(CN)2)2], (AsPh4)2[Pb(Se2C=C‐(CN)2)2], and (NBu4)2[Se(Se2C=C(CN)2)2] have been prepared and characterized by single‐crystal structure analysis. The molecular structures of the complex anions 1–3 are significantly influenced by the presence of stereochemically active lone pairs. 1 is dimeric with an Se4Tl2 octahedral centre with a Tl–Tl distance of 3.547(4) Å and an average Tl–Se bond length of 3.143(4) Å. In 2 Pb constitutes the centre of a distorted pseudo‐trigonal bipyramid PbSe4E [Pb–Seave = 2.948(3) Å] with one equatorial position obviously occupied by the lonepair E. In 3 the ligands are coordinated to the central Se, which is situated in a centre of symmetry, in an undistorted way giving rise to a Ψ‐octahedral SeSe4E2 geometry [Se–Seave = 2.617(2) Å]. The compounds (AsPh4)2 · 1, (AsPh4)2 · 2 and (NBu4)2 · 3 have been decomposed thermally to yield TlSe, PbSe as well as Se. The observed contamination of TlSe and PbSe with As is avoided by using (NBu4)2 · 1 and (NBu4)2 · 2 as precursor materials.
Die Darstellung und Strukturaufklärung der als Bu4N‐Salze (Bu = n‐C4H9) isolierten dimeren AuI‐Komplexe des 1,1‐Dicyanoethen‐2,2‐thioselenolats (i‐mnts) und des 1,1‐Dicyanoethen‐2,2‐diselenolats (i‐mns) werden beschrieben. Sie kristallisieren zueinander isotyp (monoklin, Raumgruppe P21/c, Z = 2) mit folgenden Gitterkonstanten: (Bu4N)2[Au(i‐mnts)]2; a = 14,078(3) Å, b = 8,912(3) Å, c = 20,142(4) Å β = 106,32(5)°; (Bu4N)2[Au(i‐mns)]2; a = 13,998(3) Å, b = 9,125(3) Å, c = 20,039(2) Å, β = 105,12(5)°. Ab‐initio‐Hartree‐Fock‐Rechnungen unter Zugrundelegung der experimentell bestimmten Geometrie mit Kristallfeldsimulation liefern einen positiven Wert der AuAu‐Bindungsordnung, der darauf hindeutet, daß der kurze AuAu‐Abstand (2,810(1) äR) auf schwache bindende Wechselwirkungen zwischen den d10‐Metallzentren zurückgeführt werden kann.
C 2 H 5)4N]4[Cu8 { SeaC=C( CN)2} 6], 4C8H20 N÷.C24N12Cu8Se42 -, Mr = 2433.3, monoclinic, P2Jc, a=14.830(2), b=17.690(3), c = 16.040 (3) A,/3 = 100.61 (4) °, V = 4136.0 (7) A 3, Z = 2, Dx = 1-954 Mg m -3, A(Ag Ka) = 0.5597/~, tx = 4.68 mm-l, F(000) = 2336, T = 298 K, R = 0.056 for 3844 observed reflections. The title compound is isostructural with the corresponding sulfur ligand compound [(C2Hs)nN]4[fu8 { S2C=C(CN)2} 6] and consists of a distorted cube of Cu atoms with an average Cu--Cu distance of 2.842 A. The diselenolate ligands are directed perpendicular to the Cu8 cube faces and are bridged via the SezC-bite to each of two parallel Cu---Cu edges with an average Cu--Se distance of 2.371 A.
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