The correlations between structural and electronic properties of the bismuth cyclopentadienyl complexes of the types [(C5R5)(n)Bi-n](q+) (where R = H, Me; n = 1, q = 2; n = 1-4, q = 0) and (C5R5)BiX2 (where R = H, Me; X = Cl, Br, l) were studied with quantum-chemical calculations. The influence of the ligand, significant variations in the Bi-C bond lengths, haptotropic shifts with distortion of the C5R5 ring, Jahn-Teller splitting, interstabilization effects, and the role of the lone pairs on p-block element-unalkylated or peralkylated cyclopentadienyl ring interactions were examined to obtain qualitative and quantitative pictures of the intramolecular C5R5-Bi interactions. Our theoretical investigations of monovalent and trivalent bismuth cyclopentadienyl complexes give an insight into the geometric and electronic structures, the relative stabilities and further behavior of this kind of compounds.