[PhP(S)(NMeNH2)2]ZnCl2: A Reagent for the Synthesis of Polymetallic Complexes. X-ray Structure of the Electroactive Compound [PhP(S)(NMeN=CHC5H4FeCp)2]ZnCl2

Article abstract of DOI:10.1021/ic00120a035

The zinc complex [PhP(S)(NMeNH2)2]ZnCl2 (2), cleanly obtained by reaction of the phosphodihydrazide PhP(S)(NMeNH2)2 (1) with ZnCl2, is a good reagent in producing new polymetallic compounds by condensation reaction with aldehydes. The reaction of 2 with terephthalaldehyde (3) in a 2/1 or 1/1 stoichiometry leads selectively to the acyclic zinc compound [C6H4-1,4-(CH=NNMePhP(S)NMeNH2)2][ZnCl2]2 (6) or to the macrocyclic zinc complex [PhP(S)C6H4-1,4-(CH=NNMe)2]2[ZnCl2]2 (7). Reaction of compound 2 with 2 equiv of ferrocenecarbaldehyde affords the zinc-iron phosphodihydrazone complex [PhP(S)(NMeN=CHC5H4FeCp)2]ZnCl2 (8) whose structure has beendetermined by X-ray crystallography. Crystal data: triclinic P1-, with a = 12.798(1) ?, b = 14.639(2) ?, c = 11.744(2) ?, α =111.74(1)°, β = 115.92(1)°, γ = 68.36(1)°, V = 1780.9 ?**3, Z = 2; R = 0.037, Rw = 0.044 for 3345 observations and 448 variable parameters. In this neutral trimetallic complex, the Zn(II) center adopts a pseudotetrahedral geometry. This structure is characterized by a five-membered ring with the Zn(II) bonded to the S atom and to one of the N atoms of the phosphodihydrazone ligand PhP(S)(NMeN=CHC5H4FeCp)2 (9). Variable-temperature NMR investigations of 8 show that 9 can act as a hemilabile ligand toward ZnCl2 through an exchange process between the two hydrazone arms in solution. Electrochemical study ofcomplex 8, when compared to the ferrocenyl ligand 9, shows that ZnCl2 complexation induces a shift of 80 mV toward a more anodic potential. Reaction of 2 with the ferrocene-1,1'-dicarbaldehyde also produces the bisferrocenyl dizinc macrocycle [Fe(C5H4CH=NNMePhP(S)NMeN=CHC5H4)2Fe][ZnCl2]2 (10).