{μ‐PbSe}: A Heavy CO Homologue as an Unexpected Ligand

Abstract

Reactions of [K(18-crown-6) anions, respectively.T he latter contains aP bSe ligand, ar ather uncommon homologue of CO that acts as a m-bridge between two Rh atoms.Q uantum chemical calculations yield asignificantly higher bond energy for PbSe than for CO,since the size of the ligand orbitals better matches the comparably rigid RhSe-Rh angles and the resulting Rh···Rh distance.T orationalize the bent coordination of the ligand, orbitals with significant ligand contributions and their dependence on the bonding angle were investigated in detail.The importance of CO,b oth as al igand and ar eactant, can hardly be overestimated. Thep ublication of at otal of 43 reviews in Angewandte Chemie,41in Chemical Reviews,and more than 50 in Coordination Chemistry Reviews within the last decade reflects the huge diversity of syntheses and catalytic applications of carbon monoxide and its compounds.In contrast, apart from matrix isolation experiments, [1] the molecular and coordination chemistry of the heavier homologues of CO,t hus the neutral molecular tetrel monochalcogenides E 14 E 16 (E 14 = C…Pb;E 16 = O…Te), with (formally) divalent E 14 (II) atoms,isrestricted to complexes with carbon monochalcogenides CS,C Se,a nd CTe.[2a] Furthermore,S nO and PbO units were stabilized within pincer complexes using benzannulated bisstannylene ligands.[2b] All other examples were only discussed as intermediates in the context of spectroscopic [3][4][5][6] and/or theoretical studies, [4][5][6][7][8][9][10][11][12][13][14][15][16] such as molecular PbO which was obtained under single-atom-collision conditions from atomic Pb and O 3 . [17] Ther eason for the apparent difference between the chemistry of CO and that of its heavier homologues has been attributed to the distinctly lower bond strength of the corresponding "triple" bond with increasing atomic number, and therefore ah igher tendencyt owards aggregationultimately yielding the respective minerals,s uch as litharge and massicot in the case of PbO.[18] Nevertheless,according to calculations on PbO and PbS minerals,the nature and role of the lone pair at the Pb atom is strongly influenced by the corresponding chalcogenide ion, ranging from only small contributions of the 6s atomic orbital (due to the mixing of states) in PbO to arather high 6s contribution in the frontier orbital region of PbS. [19] Following this trend, ah igher electron density on the tetrel atom is expected for the heavier homologues of the PbE 16 series.T hus with E 16 = Se or Te, ligand activity might become possible,which will be discussed herein.In the synthesis of the mixed-valence compound [(RhPPh 3 ) 6 (m 3 -Se) 8 ]·0.5 en [20] 4 (m 3 -Se) 2 (m-PbSe)]} 2 ·1.3 en (1,F igure 1), as aw ell-reproducible side-product.Thea nion in 1 (Figure 1, top) is based on a[ Rh 3 Se 2 ] trigonal bipyramid, with two m 3 -Se bridges (Se1, Se2) in axial and three Rh atoms (Rh1-Rh3) in equatorial positions.A t first glance,t he Rh atoms adopt an approximately squareplanar coordination through two Se atoms (cis) and t...

[SnBi3]5− – ein Carbonat‐Analogon aus Metallatomen

“…[SnBi 3 ] 5À repräsentiert das erste Carbonat-Analogon, das in Lçsung synthetisiert wurde und ausschließlich aus Metallatomen besteht. Damit ist es mit den bereits bekannten COund CO 2 -Analogen Pb-Se [53] und [Bi-Zn-Bi] 4À [19] [19] Bis jetzt wurden metallische Carbonat-Analoga nur in Zintl-Phasen beobachtet, [44] wie in Cs 5 TtPn 3 (Tt = Si, Ge; Pn = P, As), [45] Cs 6 InAs 3 und Cs 6 AlSb 3 . [46] Interessanterweise kommen in der ebenfalls über Festkçrperreaktionen erhaltenen Verbindung K 5 SnBi 3 keine [SnBi 3 ] 5À -Anionen, sondern stattdessen dimere [Sn 2 Bi 6 ] 10À -Einheiten vor, die aus zwei kantenverknüpften SnBi 4 -Tetraedern bestehen, welche Sn-Bi-Einfachbindungen ausbilden.…”

“…Damit ist es mit den bereits bekannten COund CO 2 -Analogen Pb-Se [53] [19] Bis jetzt wurden metallische Carbonat-Analoga nur in Zintl-Phasen beobachtet, [44] wie in Cs 5 TtPn 3 (Tt = Si, Ge; Pn = P, As), [45] Cs 6 InAs 3 und Cs 6 AlSb 3 . Damit ist es mit den bereits bekannten COund CO 2 -Analogen Pb-Se [53] [19] Bis jetzt wurden metallische Carbonat-Analoga nur in Zintl-Phasen beobachtet, [44] wie in Cs 5 TtPn 3 (Tt = Si, Ge; Pn = P, As), [45] Cs 6 InAs 3 und Cs 6 AlSb 3 .…”

Synthesis and Systematic Structural Analysis of Cationic Half‐Sandwich Ruthenium Chalcogenocarbonyl Complexes

“…[1] Nonetheless, the heaviercongeners, namely selenocarbonyl (CSe) and tellurocarbonyl (CTe) complexes have received less attention, [1a, 2] probably because hard-to-use reagents, such as carbon diselenide [3] and alkali-metal (hydro)chalcogenides, [4] are often required for the synthesis of these compounds. [5,6] The limited availability of such CSe and CTec omplexes [7,8] has so far hampered systematics tudies on chalcogenocarbonyl (CE:E = O, S, Se, Te ) complexes of transition metals (Scheme 1). However,t ob etter understand the differences between such CE ligands, it is desirable to conduct systematic structurala nalyses on as eries of CE complexes that include CSe and CTecomplexes.…”

Reasons for the Discoloration of Postconsumer Poly(ethylene terephthalate) during Reprocessing

“…[5,6] More than 90% of PET is manufactured with antimony catalysts. [10][11][12] Other common catalysts for the PET production are titanium compounds (e.g., titanium tetraisopropoxide) and germanium compounds (e.g., GeO 2 ). [2,13] However, the use of titanium alkoxides as catalysts leads to an undesirable yellowish color of PET.…”