THROUGH-SPACE TRANSMISSION OF POLAR SUBSTITUENT EFFECTS IN THE BICYCLO[1.1.1]PENTANE RING-SYSTEM AS MONITORED BY SN-119 NMR CHEMICAL-SHIFTS- A C-13 AND SN-119 NMR-STUDY OF TUTED-(X)BICYCLO[1.1.1]PENT-1-YLTRIMETHYLSTANNANES

A series of 3-substituted(X)bicyclo [1.1.1] pent-1-yltrimethylstannane s (3) were synthesized and their Sn-119 and C-13 NMR spectra were reco rded. The Sn-119 substituent chemical shifts (SCS) and the one-bond ca rbon-tin coupling constants [(1)J(C-13,Sn-119)] were analyzed in terms of possible substituent-probe interactions. The study clearly reveals that the Sn-119 NMR parameters of 3 are remarkably sensitive to modul ation of the through-space back-or rear-lobe interactions between the bridgehead bond molecular orbitals by the electronic character of the substituent. An extraordinarily large four-bond tin-tin coupling const ant in 3 (X = SnMe3) highlights the significance of through-space brid gehead-bridgehead interactions in this system. (C) 1997 John Wiley & S ons, Ltd.