ISSN:
0009-2940
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, XXXVII. Investigations on the Reactivity and decomposition of Unstable OxaphosphamanganacyclopentanesThe thermally labile five-membered metallacycles (OC)4MnPPh2OCHR1CHR2 (3a - c) [R1 = H: R2 = H (a), CH3 (b); R1 = CH3: R2 = H (c)] are obtained by reductive cycloelimination of (OC)4BrMnPPh2OCHR1CHR2Cl (2a - c) with sodium amalgam at 0 °C in ether. According to kinetic investigations the decomposition of 3a - c, which results in the formation of [(OC)4MnOPPh2]2 (4) and ethene or propene, respectively, follows a first-order rate law. The estimated activation parameters δH*, δS*, and δG* indicate decreasing stability within the series 3b 〉 3a 〉 3c. The action of CO or HBr on 3a generates the phosphane oxide complex (OC)5MnP(Ph)2O (5) and (OC)4BrMnPPh2OH (6), respectively. Sulfur dioxide is easily inserted into the Mn - C s̰-bond of 3a - c with formation of the stable cyclic sulfinato-S complexes (OC)4MnPPh2OCHR1CHR2SO2 (7a - c).
Notes:
Die thermisch labilen fünfgliedrigen Metallacyclen (OC)4MnPPh2OCHR1CHR2 (3a - c) [R1 = H: R2 = H (a), CH3 (b); R1 = CH3: R2 = H (c)] erhält man durch reduktive Cycloeliminierung von (OC)4BrMnPPh2OCHR1CHR2Cl (2a - c) mit Natriumamalgam bei 0 °C in Ether. Nach kinetischen Untersuchungen folgt der Zerfall von 3a - c in [(OC)4MnOPPh2]2 (4) und Ethen bzw. Propen dem Geschwindigkeitsgesetz 1. Ordnung. Für die abnehmende Stabilität in der Reihe 3b 〉 3a 〉 3c sprechen die abgeschätzten Aktivierungsparameter δH* δS* und δG*. Die Einwirkung von CO oder HBr auf 3a liefert den Phosphanoxid-Komplex (OC)5MnP(Ph)2O (5) bzw. (OC)4BrMnPPh2OH (6). Schwefeldioxid wird glatt in die Mn - C-s̰-Bindung von 3a - c unter Bildung der stabilen cyclischen Sulfinato-S-Komplexe (OC)1MnPPh2OCHR1CHR2SO2 (7a - c) eingeschoben.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19841170816
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