Synthesis and study of fire suppression efficiency of novel binuclear complexes, (DPPF)ZnX2 (X = Cl, Br, and I)

Abstract Ferrocene, an iron complex, is known for its strong flame inhibition effect. Previous study suggested that a complex composed of parts capable of flame inhibition may exhibit an enhanced flame inhibition effect. While previous studies have focused on the combustion-inhibiting effects of mononuclear complexes such as ferrocene, this effect can be expected to be greater for binuclear complexes, due to the higher metal content that acts as flame inhibitors. In this study, novel binuclear complexes, 1,1-bis (diphenylphosphino) ferrocene (DPPF)ZnX 2 where X = Cl, Br, or I, containing iron and zinc cations, were synthesized with an aim to develop high-performance fire-extinguishing agents. The flame inhibition effects of (DPPF)ZnX 2 complexes on the combustion of cellulose, a common combustible material, were investigated. The results showed that the (DPPF)ZnCl 2 , (DPPF)ZnBr 2 , and (DPPF)ZnI 2 complexes outperformed ammonium dihydrogen phosphate, an active component of conventional ABC extinguishing agents, by factors of 38.6, 37.5, and 47.3, respectively. Moreover, kinetic investigations of pyrolysis using thermogravimetric analysis revealed that cellulose with (DPPF)ZnX 2 ((DPPF)ZnX 2 /cellulose) had an activation energy 1.3–1.5 times greater than that of pure cellulose, indicating that (DPPF)ZnX 2 hindered the pyrolysis of cellulose. These findings confirm the flame-inhibitory effects of (DPPF)ZnX 2 in the solid phase, demonstrating its capability as a suitable fire extinguisher agent.