The octaphosphine {cyclo-((P4Bu3)-Bu-t)}(2) (1) possesses a multifaceted coordination chemistry. The predominant binding mode is a P,P-chelate, e.g., in the monometallic chelate complex [MLL'(1-kappa P-2(2),P-4')] in which the ligand 1 adopts a gauche conformation. Examples include square-planar (M = Rh-I, L = CO, L' = Cl (2), M = Pd-II, L = L' = Cl (3), M = Pt-II, L = L' = Cl (9)), tetrahedral (M = Co-I, L = NO, L' = CO (4)), and trigonal-planar complexes [ML(1-kappa P-2(2),P-4')] (M = Pd-0, L = PPh3, (5), M = Cu-I, L = Br (6)). With 2 equiv of [CuBr(SMe2)], a dinuclear complex [(CuBr)(2)(1-kappa P-2(2),P-2',kappa P-2(4),P-4')] (7) was obtained which features a synperiplanar conformation of the octaphosphine. A second coordination mode was also observed in [PtCl2(1-kappa P-2(1),P-2')] (10) in which the bridge phosphorus atom in octaphosphine 1 is involved in the chelation, with the ligand in an antiperiplanar conformation. Thermolysis of selected complexes showed them to be suitable candidates for the generation of phosphorus-rich metal phosphides MPx (x > 1).