ISSN:
0009-2940
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Multiple Bonds Between Main Group Elements and Transition Metals, XII. Generation and Complex Stabilization of Arsinidene and Diarsene Fragments by Complex-Induced Degradation of MonoarsaneThe Lewis base monoarsane is degraded in the presence of the solvens complex (η5-C5Me5)Mn-(CO)2THF (1; Me = CH3) to yield, under elimination of hydrogen, the arsinidene fragment AsH which latter species acts as a symmetrically bridging ligand in the novel dinuclear organometallic compound 2, thus forming a bent Mn, As, Mn′ three-center four-electron system (dMn — As = 224.7(1) pm, Mn — As — Mn′ = 139.3(1)°; single-crystal X-Ray structure analysis). The arsenic-hydrogen bond present in 2 is kinetically labile, allowing carbene insertion and As — As coupling reactions. Thus, treatment of 2 with diazoalkanes N2=CRR′ leads to N2-elimination and formation of the carbene insertion products (μ, η2-AsCHRR′)[(η5-C5Me5)Mn(CO)2]2 (3a - c); in these products, one of the two manganese-arsenic bonds originally present in the precursor compound 2 is bridged by the respective alkyl groups. Vacuum thermolysis of solid 2 cleanly proceeds at 120 - 140°C with climination of hydrogen and formation of the μ,η2-diarsane complex 4 that has a butterfly-type Mn2As2-structure with a very short As — As bond (dMn — As = 255.5 pm; av., dAs — As = 222.5(2) pm, double bond; no Mn — Mn bond; single crystal X-Ray structure analysis). Consecutive H2-elimination reactions are also observed when the THF complex 5 reacts with monoarsane; here, the tetranuclear diarsane complex 8 is formed which is structurally derived from coupling of two μ-arsinidene precursor species of type 6.
Notes:
Unter Wasserstoff-Eliminierung wird die Lewis-Base Monoarsan in Gegenwart des Solvens-Komplexes (η5-C5Me5)Mn(CO)2THF (1; Me = CH3) zum Arsiniden-Liganden AsH abgebaut, der in der neuen zweikernigen Komplexverbindung 2 als symmetrischer Brückenligand vorliegt und mit den beiden Metallatomen ein gewinkeltes Dreizentren-Vierelektronen-Bindungssystem bildet (dMn — As = 224.7(1) pm, Mn — As — Mn′ = 139.3(1)°; Einkristall-Röntgenstruktur-analyse). Die in 2 vorliegende Arsen-Wasserstoff-Bindung ist kinetisch labil und erlaubt Carben-Insertionen sowie As — As-Kupplungsreaktionen. Umsetzung mit Diazoalkanen N2=CRR′ ergibt unter N2-Eliminierung die Carben-Insertionsprodukte (μ, η2-AsCHRR′)[(η5-C5Me5)Mn-(CO)2]2 (3a - c) in denen eine der beiden Mangan-Arsen-Bindungen des Edukts 2 alkylverbrückt ist. Vakuumthermolyse von festem 2 bei 120 - 140°C führt unter H2-Abspaltung glatt zum μ,η2-Diarsen-Komplex 4, der eine Mn2As2-Butterfly-Struktur mit einer sehr kurzen As — As-Bindung besitzt (dMn — As = 255.5 pm, Mittelwert; dAs - As = 222.5(2) pm, Doppelbindung; keine Mn — Mn-Bindung; Einkristall-Röntgenstrukturanalyse). Konsekutive H2-Eliminierungsschritte begleiten auch die Reaktion des substitutionslabilen THF-Komplexes 5 mit Monoarsan zum vierkernigen Diarsen-Komplex 8, der als intermolekulares Kupplungsprodukt zweier μ-Arsiniden-Komplexvorstufen vom Typ 6 aufzufassen ist.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19851180624
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