TRI(TERT-BUTYL)PLUMBYL DERIVATIVES OF GROUP-14 ELEMENTS - MULTINUCLEAR MAGNETIC-RESONANCE STUDIES - DETERMINATION OF COUPLING SIGNS

A solution of tri(tert-butyl)plumbyl-lithium in THF (2) was prepared b y the reaction of hexa(tert-butyl)diplumbane (1) with an excess of lit hium. Treatment of this reagent with a variety of Group 14 electrophil es gave tetraorganolead compounds (Bu3Pb)-Bu-t-R (3, R=Me (a), Et (b), Pr-n (c), Bu-n (d), CH2Ph (e), CH2SiMe3 (f)), plumbylsilanes (Bu3Pb)- Bu-t-(SiR1R2)-R-2 (4, R-1 = R-2 = Me (a), R-1 = Me, R-2 = (BU)-B-t (b) , R-1 = Me, R-2 = SiMe3 (c), R-1 = Me, R-2 = Ph (d), R-1 = R-2 = Ph (e )), one plumbylgermane (Bu3Pb)-Bu-t-GeMe3 (5a), plumbylstannanes (Bu3P b)-Bu-t-SnR33 (6, R-3 = Me (a), Et (b), Bu-n (c), Bu-t (d), Ph (e), 1, 1'-ferrocenediyl (f)), and hexaorganodiplumbanes (Bu3Pb)-Bu-t-PbR34 (7 , R-4 = Me (a), Et (b), Pr-t (c), (n)Hex (d), (c)Hex (e)], (Pr3Pb)-Pr- t-PbEt3 (10) and Bu-t(2)(Me)Pb-Pb(Me)Bu-t(2) (II) as a side product. T he plumbylstannanes Et3Pb-SnMe3 (9a) and (Pr3Pb)-Pr-t-SnMe3 (9b) were prepared for comparison of NMR data. All compounds were characterized by H-1, C-13, Si-29, Sn-119 and Pb-207 NMR data. Signs of coupling con stants (n)J((207)pb, C-13) (n = 1, 2) (1)J(Pb-207, Si-29), (1)J(Pb-207 , Sn-119) and (1)J((207)pb, (207)pb) were determined by appropriate 1D heteronuclear double resonance experiments and 2D heteronuclear shift correlations. The influence of the (Bu3Pb)-Bu-t group on the bonding situation is reflected by sign changes of several coupling constants w hen compared with analogous trimethyllead derivatives. (C) 1997 Publis hed by Elsevier Science S.A.