Rationally designed topological arrangement of multinuclear transition metal centers is of fundamental importance to create diverse functions applicable to catalysts, electronic, photochemical, and magnetic materials, and molecular devices. We have systematically studied structurally constrained multinuclear metal clusters by utilizing multidentate phosphine ligands. This highlight review summarizes recent progress of our investigations of the synthesis of low-valent metal clusters supported by linear tetradentate phosphine ligands, Ph2PCH2P(Ph)(CH2)(n)-P(Ph)CH2PPh2 (n = 1-4) and Ph2PCH2P(Ph)N(Ph)P(Ph)CH2-PPh2, mainly focusing on linear noble metal chains and rings and copper hydride clusters.