A completely ordered polysilane polymer has been prepared. The surface tension of polysilane, polymers has been investigated, and found to span a large range from 20 to 52 mdyne/cm. The polymer poly(n-butyl-n-hexylsilylene) was found to have a hexaponal columnar structure, at all temperatures from -80 to +200 C. Many polysilane copolymers were also observed to have columnar liquid crystalline structures. Several linear polysilane oligomers were synthesized as model compounds for the study of high polymers. New types of alpha-pi conjugated polymers were synthesized and studied, based on alternating polysilane and acetylene groups. New disilenes were synthesized, including the first example of a disilene with a silyl substituent. The oxidation of disilenes by oxygen was investigated and found to produce 1,2-disilaoxetanes which rearrange intramolecularly to 1,3-cyclodisiloxanes. Disilenes were found to react with aldehydes, ketones and thioketones by 2+2 cycloaddition to produce four-membered ring compounds. Reactions of disilenes with ketenes and acid chlorides were also investigated. With white phosphorus, disilenes react to produce nobel bicyclobutane molecules which may be further converted to tricyclic asterane structures. The first platinum derivatives of disilenes were synthesized. The first siladiimides have been synthesized. These are salts of anions containing partial double bounds between silicon and each of two nitrogen atoms. The chemical reactions, spectroscopy and structure of siladiimides has been investigated.