Abstract
1,1,3,3-Tetramethyl-2-organo(R)-1,3-distanna-2-phospha-[3]ferrocenophanes [R = Me (2a), tBu (2b), C6H11 (2c), Ph (2d)] and one arsa-analogue 2d(As) were obtained from the reaction of 1,1′-bis(chlorodimethylstannyl)ferrocene 1 with either bis(trimethylsilyl)methylphosphane or the dilithio derivatives, Li2PR and Li2AsPh, respectively. All compounds 2 react with chalcogens (oxygen, sulfur, selenium) by cleavage of the Sn-P bonds and formation of the known 1,3-distanna-2-chalcogena-[3]ferrocenophanes. In contrast, 2d traps pentacarbonylmetal fragments [M(CO)5] to give the stable phosphane complexes [M = Cr (4d), Mo (5d), W (6d)]. The 1,1′-bis(diorganophosphanostannyl)ferrocenes [R = tBu (3b), Ph (3d)] were prepared for comparison of NMR data. The ferrocenophanes 2 are fluxional with respect to fast movement of the cyclopentadienyl rings which induces inversion at the pyramidal phosphorus atom. This dynamic process is slow in the cases of 2d(As) and of the pentacarbonyl complexes 4d - 6d. All new compounds were characterised by 1H, 13C, 31P and 119Sn NMR spectroscopy. Various 2D heteronuclear shift correlations (e.g. 31P/1H and 119Sn/1H ) were carried out for the compounds 2 and also for non-cyclic derivatives such as bis(trimethylstannyl)phenvlphosphane and -arsane in order to determine absolute signs of coupling constants [e.g. 1J(119Sn,31P) > 0 and 2J(119Sn,117Sn) < 0]. The NMR data suggest that the molecular frameworks of the ferrocenophanes 2 are not particularly strained.
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