The theoretical study of electronic structure of selected silanethiols X 3SiSH (X = H, C 2H 5, OCH 3, F, Cl or Br) and the related anions X 3SiS − was carried out using density functional theory (DFT) geometry optimizations, analysis of natural bond orbitals (NBO) and bond orders. Structures were examined to find correlations between selected bond lengths. Short Si–S bonds always accompany long Si–X bonds. Delocalization of lone pairs of sulfur atoms to antibonds σ ∗ Si – X gives a simple, but not fully satisfactory, explanation of this phenomenon. The shortening of Si–S bond on deprotonation of X 3SiSH is also observed in carbosilanethiols, although Si–C bonds lengthen not much, so increasing of strength of σ SiS bond by change in the overlap integral seems to be the main reason of Si–S shortage. The relationship between the two effects was analyzed. Geometry changes during deprotonation of trialkoxysilanethiols provide new arguments for justification of exceptionally low acidity of (Bu t O) 3SiSH. X-ray structures of known copper group metals’ trialkoxysilanethiolates and trialkyl(aryl)silanethiolates are reviewed and their common features described. Total Mulliken charge of the whole silanethiolato rest gives relatively good correlation with the shortening of the Si–S bond lengths. Characteristic tendency to form homoleptic tetramers [{R 3SiSM} 4] (R = alkyl, aryl or alkoxy group) or mononuclear heteroleptic complexes R 3SiSML n (M = Cu, Ag, Au, L = phosphine or amine, n = 1–3) is discussed in terms of frontier orbitals’ properties of the R 3SiSM fragment.