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Bis-(1-tricyclo{lcub}'2,7){rcub}heptyl)dimethyl-silane (22) and-germane (23) and tetrakis-(1-tricyclo{lcub}'2,7){rcub}heptyl)silane (14)were synthesized from 1-tricyclo{lcub}'2,7){rcub}heptyllithium (20). 2,10-Disila- (30), 2,10-digerma- (32), and 2-germa-10-sila (31) -2,2,10,10-tetramethylheptacyclo{lcub}'1,11).0('3,8).0('3,9).0('4,9).0('11,16){rcub}hexadecaneswere synthesized from the requisite dilithio- derivatives of either 22or 23. These dilithio- derivatives were also used to synthesize 2,2'-spirobi-2,10-disila- (33), 2,2'-spirobi-2,10-digerma- (35), 2,2'-spirobi-2-sila-10-germa- (33), and 2,2'-spirobi-2-germa-10-sila (34), 10,10-dimethylheptacyclo{lcub}'1,11).0('3,8).0('3,9).0('4,9).0('11,16){rcub}hexadecanes.2,10-Disila-2,2-bis(1-tricyclo{lcub}'2,7){rcub}heptyl)-10,10-dimethyl-heptacyclo{lcub}'1,11).0('3,8).0('3,9).0('4,9).0('11,16){rcub}hexadecane (15) was synthesized from the dilithio- derivative of 14. The UV spectra of 14 and 30 show weakly enhanced end absorption when compared to composite spectra of either the corresponding bicyclobutane and n-butyltrimethylsilane or 1-trimethylsilyltricyclo{lcub}'2,7){rcub}heptane (8a). These results suggest that the central bonds of the bicyclobutane moieties interact through the vacant silicone d-orbitals. The use of NMR as a probe for the electronic effects in such molecules revealed a particularly interesting trend in ('13)C NMR. Compounds 30-32, 33, 35, and 36 showed a consistent downfield shift for carbon atoms 2 and 6 of the tricycloheptyl group of 5-6 ppm when compared to tricyclo{lcub}'2,7){rcub}heptane (17), 8a, 8b, 9a, 22, or 23. This deshielding appears to arise as a result from some form of diamagnetic ring current which is suggested by the results of the UV spectra, and photochemical results substantiate the presence of novel electronic effects in such molecules. The results from X-ray crystallographic studies of 30 and 33 also can help strengthen this argument since both compounds exhibit abnormally long central bonds in the bicyclobutane groups which can be attributed to a conjugative overlap of the central bonds with the vacant d-orbitals on silicon.