Reduktive Enthalogenierung von (Cl, Br)RP–CH2–PR(Cl, Br) mit Fe2(CO)9– Bildung von Komplexen mit gespannten Diphosphirangerüsten und bifunktionellen Phosphidobrücken (µ2-PR)2CH2 / Reductive Dehalogenation of (Cl, Br)RP–CH2—PR(Cl, Br) with Fe2(CO)9– Formation of Complexes with Strained Diphosphirane Skeletons and Bifunctional Phosphido Bridges (μ2-PR)2CH2

Autor: Peter C. Knüppel, Franjo Gol, Frank Bitterer, Carl Krüger, F. Dörrenbach, David J. Brauer, Othmar Stelzer, Yi‐Hung Tsay
Rok vydání: 1991
Předmět:
Zdroj: Zeitschrift für Naturforschung B. 46:1131-1144
ISSN: 1865-7117
0932-0776
DOI: 10.1515/znb-1991-0901
Popis: Reductive dehalogenation of the bifunctional methylene bridged halogenphosphines XRP-CH2—PRX (X = Cl, Br; R = iPr, tBu, 2,4,6-R′3C6H2 (R′ = Me, iPr, tBu), N(SiMe3)2 and 2,6,4-tBu2MeC6H2—O) with diironenneacarbonyl affords phosphido complexes with strained RP—CH2—PR backbones, Fe2(CO)6[(μ2-PR)2CH2] (8a-8g). X-Ray structural analyses of the 2,4,6-iPr3C6H2 (8d) and 2,6,4-tBu2MeC6H2—O derivatives (8g) reveal that the Fe2P2C skeletons have remarkably small P—C—P angles (83,7(4)° (8d), 78,6(1)° (8g)). The dehalogenation of XRP—CH2—PRX with Fe,(CO)9 is preceded by the formation of iron carbonyl complexes (RXP—CH2—PRX)[Fe(CO)4]n (n = 1, 2). For derivatives with bulky substituents R complex formation proceeds diastereoselectively. In case of 3 b the diastereoisomers could be separated and a crystallographic examination of the racemic form showed that the P—C—P backbone possesses C2 symmetry with an approximately trans conformation of the P—C—P fragment. The P-atoms occupy the equatorial position within the Fe(CO)4P units. The chloro-phosphido bridged complex Fe2(CO)6(μ2-Cl)(µ2-PR—CH2—PRCl—Fe(CO)4) (4a), formed by oxidative addition of a P—Cl bond to Fe(0), or diphosphiranes and their complexes [(RP)2CH2][Fe(CO)4]n (n = 0-2; 5-7) have been isolated as intermediates of the XRP-CH2—PRX dehalogenation. The diphosphiranes 5 were synthesized independently by reduction of the halogenphosphines XRP—CH2—PRX with lithium or magnesium. An X-ray examination of 4a showed that it contains a μ2-PR—CH2—PRCl backbone which bridges Fe2(CO)6(μ2-Cl) and Fe(CO)4 units, the P—C—P angle being remarkably large, 127,3(1)°.
Databáze: OpenAIRE
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