(Graphical Abstract) The reaction of Ph3Bi with a sterically hindered phosphinic acid, 1,1,2,3,3-pentamethyltrimethylene phosphinic acid, {cycP(O)OH·2H2O}, at two different temperatures, one at refluxing conditions and another at room temperature, in tetrahydrofuran has been investigated. At refluxing conditions, cleavage of two Bi-C bonds (of BiPh3) leads to the formation of a 16-member macrocycle [(PhBi)4(cycPO2)8] (1). On the other hand, the reaction at room temperature leads to the cleavage of one Bi-C bond only, affording a 1D polymer [(Ph2Bi)(cycPO2)]n, ((1,1,2,3,3-pentamethyltrimethylene phosphinate is denoted as cycPO2) (2). Both the complexes were characterized by single crystal X-ray diffraction. In both complexes the phosphinate ligands are present in an anisobidentate (bridging) coordination mode. Copyright © Taylor & Francis Group, LLC.