The correlations between structural and electronic properties of the bismuth cyclopentadienyl complexes of the types [(C(5)R(5))(n)Bi(n)](q+) (where R = H, Me; n = 1, q = 2; n = 1-4, q = 0) and (C(5)R(5))BiX(2) (where R = H, Me; X = Cl, Br, I) 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 C(5)R(5) 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 C(5)R(5)-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.