l , 3 - Distanna - 2 - phospha - [ 3 ] ferrocenophanes - Synthesis , Reactivity and NMR Spectroscopic Properties

Z. Naturforsch. 54 b, 57-62 (1999); received July 28, 1998 Ferrocene, Tin, Phosphorus, NMR Data, Coupling Signs l,l,3,3-Tetramethyl-2-organo(R)-l,3-distanna-2-phospha-[3]ferrocenophanes [R = Me (2a), rBu (2b), CöH i i (2c), Ph (2d)] and one arsa-analogue 2d(As) were obtained from the reaction of l,l'-bis(chlorodimethylstannyl)ferrocene 1 with either bis(trimethylsilyl)methylphosphane or the dilithio derivatives, Li2PR and Li^AsPh, respectively. All compounds 2 react with chalcogens (oxygen, sulfur, selenium) by cleavage of the Sn-P bonds and formation of the known l,3-distanna-2-chalcogena-[3]ferrocenophanes. In contrast, 2d traps pentacarbonylmetal frag­ ments [M(CO)5] to give the stable phosphane complexes [M = Cr (4d), Mo (5d), W (6d)]. The l,l'-bis(diorganophosphanostannyl)ferrocenes [R = fBu (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 'H, i3C, 31P and 1 l9Sn NMR spectroscopy. Various 2D heteronuclear shift correlations {e.g. 11P /1H and ll9Sn/'H) were carried out for the com­ pounds 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. 7(n Sn,’'P) > 0 and 2J(] l9Sn,' l7Sn) < 0]. The NMR data suggest that the molecular frameworks of the ferroceno­ phanes 2 are not particularly strained.