The synthesis and complexation behavior of a novel bis-phosphine ligand based on a calix-[4]arene scaffold, 5,17-bis(diphenylphosphino)-25,26,27,28-tetrabenzyloxycalix[4]arene (3), are reported. Reaction of 3 with PdCl 2 (cod) under dilute conditions results in formation of the trans-coordinated dinuclear complex [PdCl 2 ‚3] 2 (4). The X-ray structure of 4 reveals that the two phosphinocalix[4]arene molecules are linked by the two PdCl 2 fragments. On the other hand, reaction of 3 with PtCl 2 (cod) affords the cis-chelating mononuclear complex PtCl 2 ‚ 3 (5). The X-ray structure, low-temperature NMR measurements, and geometry optimization of 5 reveal that the structure in solution at -80 °C and in solid-state has a C 1 symmetry where the P-Pt-P plane is inclined and the calix[4]arene moiety is twisted. It was also found that 3 reacts with [Pd(η 3 -C 3 H 5 )(cod)]BF 4 to yield the corresponding cationic complex [Pd(η 3 -C 3 H 5 )‚3]BF 4 (6) quantitatively. Low-temperature NMR measurements suggest that 6 exists as a mixture of two stereoisomers (6a and 6b) possessing a C 1 symmetry. Although both 5 and 6 exhibit C 1 structure at -80 °C, their NMR spectra measured at 20 °C indicate a C 2v symmetry for 5 and a C s symmetry for 6. These fluxional behaviors of 5 and 6 in solution are caused by two separable motions: rollover motion of the coordination plane (R motion) and twist motion of the calix[4]arene scaffold (T motion).