Inversely Polarized Phosphaalkenes as Phosphinidene‐ and Carbene‐Transfer Reagents

Abstract

The reaction of the inversely polarized phosphaalkenes RP=C(NMe 2 ) 2 [R = tBu (1a), Cy (1b), 1-Ad (1c), Ph (1d), Mes (1e)] with an excess of diphenyl ketene in n-pentane affords the zwitterionic adduct (Me 2 N) 2 C-C(O)=CPh 2 (2) and the 3,5-dibenzhydrylidene-1,4,2-dioxaphospholanes 4a-e. The reaction of 1a with Ph 2 C=C=O in concentrated acetonitrile solution gives 4a and 5-benzhydrylidene-2-tert-butyl-4,4-diphenyl-1,2-oxaphospholan-3-one (6a) as a by-product. In contrast, treatment of Me 3 SiP=C(NMe 2 ) 2 (1i) with the ketene leads to the formation of 2-phospha-1,3-butadiene (5). The thermolabile phosphaalkene 8 decomposes into an imid-

Reactivity of the Inversely Polarized Arsaalkenes R–As=C(NMe2)2 {R = [(η5‐C5Me5)(CO)2Fe], tBuC(O), 4‐Et–C6H4C(O)} towards Phosphavinylidene Complexes [η5‐(C5H5)(CO)2M=P=C(SiMe3)2] (M = Mo, W)

“…[15] In the η 3 -1,2-diphosphaallyl complex VI the resonances for the central P atom were observed at δ = -6.8 ppm (M = Mo, R = tBu) and δ = -61.6 ppm (M = W, R = tBu). [11] In the 13 C{ 1 H} NMR spectra of 4a, 5a, and 5b the carbon atoms of the 2-phospha-1-arsaallyl ligands appear as doublets at δ = 49.9 ppm (J P,C = 105.0 Hz), 35.7 (J P,C = 101.2 Hz), and 31.8 (J P,C = 98.5 Hz) ppm. The 13 C NMR resonances of the carbonyl ligands were observed at δ = 234.0 (s), 236.0 (s) (Mo-CO); 216.7 (s), 218.65 (d, J P,C = 11.5 Hz) (Fe-CO) for 4a, at δ = 222.7 (s), 224.6 (s) (W-CO); 217.1 (s), 219.0 (s) (Fe-CO) for 5a, and at δ = 222.8 (s), 223.9 (s) for 5b.…”

“…[11] The distances between the Mo atom and the terminal carbon atom in 4a as well as in VI clearly exceed the corresponding Mo-C bond lengths in 1-phosphaallyl complex VII [2.357(3) Å].…”

“…[12b] In the IR spectrum of 1,2-diphosphaallyl complexes VI ν(CO) bands were registered at ν= 1943, 1877 cm -1 (M = Mo; R = tBu) and at ν= 1938, 1851 cm -1 (M = W; R = tBu). [11] Single crystals of 4a and 5a suitable for an X-ray diffraction analysis were grown from a 1:9 mixture of diethyl ether/n-pentane at -30°C. Compound 5a is isostructural to 4a, and only the latter will be discussed in detail.…”

“…[7] Whereas 1,2-diphosphaallyllithium compounds [9] and η 1 -complexes of the isomeric 1,2-diphosphaallyl ligand V have been known for some years, [10] a paper concerning η 3 -complex VI was only recently published. [11] In this paper we report on the reactivity of inversely polarized arsaalkenes R-As=C(NMe 2 ) 2 [1: a: R = Cp*(CO) 2 -Fe, b: tBuC(O), c: 4-Et-C 6 H 4 C(O)] with phosphavinylidene complexes [Cp(CO) 2 M=P=C(SiMe 3 ) 2 ] (2: M = Mo; 3: M = W), [12] whereby the first complexes with η 3 -2-phospha-1-arsaallyl ligands are formed. Part of this work has previously been published in a short communication.…”

Synthesis of the η2‐1‐Phosphaallene Complexes [(η5‐C5H5)(CO)(NO)W{η2‐R1P=C=C(R2)H}] (R1 = tBu, Cy; R2 = Ph, H) from [(η5‐C5H5)(CO)(NO)W=C=C(R2)H] (R2 = Ph, H) and Inversely Polarized Phosphaalkenes R1P=C(NMe2)2 (R1 = tBu, Cy), and Their Structure

“…[5] Similar transformations have been effected with inversely polarized arsaalkenes. [6] Synthesis and Structure of η 2 -1-Phosphaallene Complexes FULL PAPER Scheme 3.…”