The crystal structures of di-chlorido-palladium(II), -platinum(II) and -rhodium(III) complexes containing 8-(di-phenyl-phosphan-yl)quinoline, (SP-4)-[PdCl2(C21H16NP)], (1) [systematic name: di-chlor-ido-(8-di-phenyl-phosphanyl-quinoline)-palladium(II)], (SP-4)-[PtCl2(C21H16NP)]·CH2Cl2, (2) [systematic name: di-chlorido-(8-di-phenyl-phos-phanyl-quinoline)-platinum(II) dichlorometh-ane monosolvate], and (OC-6-32)-[RhCl2(C21H16NP)2]PF6·0.5CH2Cl2·0.5CH3OH, (3) [systematic name: cis-di-chlor-ido-bis-(8-di-phenyl-phosphanyl-quinoline)-rhodium(III) hexa-fluorido-phos-phate di-chloro-methane/-methanol hemisolvate] are reported. In these complexes, the phosphanyl-quinoline acts as a bidentate ligand, forming a planar asymmetrical five-membered chelate ring. The palladium(II) and platinum(II) complex mol-ecules in (1) and (2), respectively, show a typical square-planar coordination geometry and form a dimeric structure through an inter-molecular π-π stacking inter-action between the quinolyl rings. The centroid-centroid distances between the stacked six-membered rings in (1) and (2) are 3.633 (2) and 3.644 (2) Å, respectively. The cationic rhodium(III) complex in (3) has a cis(Cl),cis(P),cis(N) (OC-6-32) configuration of the ligands, in which two kinds of intra-molecular π-π stacking inter-actions are observed: between the quinolyl and phenyl rings and between two phenyl rings, the centroid-centroid distances being 3.458 (2) and 3.717 (2) Å, respectively. The PF6 (-) anion in (3) is rotationally disordered, the site occupancies of each F atom being 0.613 (14) and 0.387 (14). The CH2Cl2 and CH3OH solvent mol-ecules are also disordered and equal site occupancies of 0.5 are assumed.