Adducts of 1,4-diazabutadienes with group IIB metal halides
1981; Elsevier BV; Volume: 51; Linguagem: Inglês
10.1016/s0020-1693(00)88320-6
ISSN1873-3255
AutoresP. L. SANDRINI, A. MANTOVANI, Bruno Crociani, Paolo Uguagliati,
Tópico(s)Ferrocene Chemistry and Applications
ResumoThe reactions of 1,4-diazabutadienes (or α-diimines) RNC(R′)C(R″)NR, DAB, (R = p-C6H4OMe, R′ = R″ = H, DABI; R = p-C6H4OMe,R′ = H, R″ = Me, DABII; R = p-C6H4OMe, R′= R″ = Me; DABIII; R = CMe3, R′ = R″ = H, DABIV) with MX2 M = Zn, Cd, Hg; X = CI, Br) yield in general 1/1 adducts. These species are assigned a monomeric configuration with a σ,σ′-N,N′, chelating DAB ligand for M = Zn, Hg, whereas the CdCl2 adducts have polymeric structures with terminal and/or bridging chlorides. In the reactions of CdCl2 with DABI or DABIV polymeric species [(CdCl2)2(DAB)]x are obtained in which all chlorides are bridging. Spectrophotometric dissociation equilibrium constants have been determined by titration methods in 1,2-dichloroethane for some Zn and Hg 1/1 adducts. The stability constants depend markedly on the substituents on the imine C and N atoms. When R = CMe3 (DAB)IV no dissociation is detected, whereas with R = p-C6H4OMe the stability constants increase in the order: DABI < DABII ⩽ DABIII which is apparently the order of increasing σ-donor ability of the α-diimine ligands. The [ZnCl2(DABI)] complex is ca. 30 times more stable than its Hg analogue. Computational details of the equilibrium measurements are also discussed.
Referência(s)