Novel Syntheses and Reactions of Phosphetanium Salts with a Planar C -C -C -P SkeletonCleavage of the P -Si bond of silylphosphanes R2P -SiMe3 (R = iPr, tBu, 2,4,6-Me3C6H2) with excess 1,3-dihalogenpropan%X -[CH2l3 -X (X = Br, I) affords phosphetanium salts [R,P -[CH213]+X-(3) in good yields. These strained four-membered ring systems are also obtained by alkylation of secondary phosphanes R2PH with X -[CH213 -X followed by deprotonation of

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1992organo-phosphorus compounds, nonmetal heterocycles organo-phosphorus compounds, nonmetal heterocycles S 0087 -237Novel Syntheses and Reactions of Phosphetanium Salts with a Planar Cyclic C-C-C-P Skeleton.-Cleavage of the P-Si bond of the silylphosphanes (I) with the 1,3-dihalopropane (II) affords the title compounds (III). These strained four-membered ring systems can also be obtained by alkylation of sec. phosphanes with (II) followed by deprotonation of the intermediate phosphonium salts [e.g. (IV) → (IIIb)]. Silylphosphanes and sec. phosphanes with less bulky substituents preferably form open-chain phosphonium salts or allyl analogues. The X-ray structure analysis of (IIIc) reveals planar geometry of the PC 3 skeleton. Reactions of (IIIb) with different nucleophiles are studied. Only with NaNH 2 and CsF, stable phosphoranes are obtained. Reactions with KOH, KOtBu, NaN(Tms) 2 (and Na(η 5 -C 5 H 5 )Fe(CO) 2 ) lead to the ring-opening products (VI). Bi-and polydentate ligands such as (VIII) and (X) are synthesized by cleavage of (IIIb) with corresponding Li phosphides. In a Wittig-type reaction, the open-chain phosphane oxides (XIII) are formed. -(BRAUER, D. J.; CICCU, A. J.; HESSLER, G.; STELZER, O.; Chem.

1994organo-iron compounds organo-iron compounds S 7100 -240Chloromethylchlorophosphanes R(Cl)P-CH2-Cl -Synthons for the Synthesis of Phosphaalkenes in the Metal-Template.-Dehalogenation of phosphane complexes of type (III) with Fe2(CO)9 (II) affords phosphaalkene clusters of type (IV). If Fe3(CO)12 (V) is used instead of Fe2(CO)9 for the dehalogenation of the phosphane complexes ( IIIa)-(IIIc) binuclear complexes with bridging R-P=CH2 ligands of type (VI) and known phosphinidene phosphaalkene clusters of type (VIII), and in the case of (IIIa) additionally the phosphido-phosphane-bridged complex (VII) are obtained. -(BRAUER, D. J.; CICCU, A.; FISCHER, J.; HESSLER, G.; STELZER, O.; SHELDRICK, W. S.; J.