0000000000814191
AUTHOR
Antonio Mantovani
Adducts of 1,4-diazabutadienes with group IIB metal halides
Abstract The reactions of 1,4-diazabutadienes (or α-diimines) RNC(R′)C(R″)NR, DAB, (R = p -C 6 H 4 OMe, R′ = R″ = H, DAB I ; R = p -C 6 H 4 OMe,R′ = H, R″ = Me, DAB II ; R = p -C 6 H 4 OMe, R′= R″ = Me; DAB III ; R = CMe 3 , R′ = R″ = H, DAB IV ) with MX 2 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 CdCl 2 adducts have polymeric structures with terminal and/or bridging chlorides. In the reactions of CdCl 2 with DAB I or DAB IV polymeric species [(CdCl 2 ) 2 (DAB)] x are obtained in which all chlorides are bridging. Spectrophotometric dissociation equilib…
Migration of bidentate anionic ligands in binuclear compounds derived from 1,2-bis(imino)propyl-palladium(II) complexes
Abstract The complexes [Pd(AB){C(NR)CMeNR}(PPh3)] (I; AB = 2,4-pentanedionate, N-methylsalicylaldiminate, pyrrole-2-N-methylaldiminate; R = p-C6H4OMe) react with ‘MCl2’ (‘MCl2’ = CoCl2, NiCl2, CuCl2, ZnCl2, [PdCl2(NCMe)2], K[PtCl3(CH2CH2)]) to give either the binuclear adducts [(PPh3)(AB)Pd{C(NR)CMeNR}MCl2] (II) or the zwitterionic isomers [(PPh3)Cl2Pd{C( NR)CMeNR}M (AB)] (III) depending on the nature of the metal M and of the anionic ligand AB. The formation of products III is accounted for in terms of an intramolecular migration of ligands between the two metal centers Pd and M of the initially formed MCl2 adducts II.
Preparation and reactivity of 1,2-bis(imino)ethylpalladium(II) complexes
Abstract The 1,2-bis(imino)ethylpalladium complex, t r a n s − [ P d C I { C ( = N R ) ︹ C H = N R } ( P P h 3 ) 2 ] (R =p-C6H4OMe, DABI) can be prepared by treatment of [Pd(PPh3)4] with two equivalents of CNC6H4OMe-p followed by slow addition of HCl at −70° C. The σ-bonded 1,2-bis(imino) group can be easily monoprotonated and undergoes acid hydrolysis to give the α-aldehydoimidoyl derivative t r a n s − [ P d C I { C ( = N R ) ︹ C H = O } ( P P h 3 ) 2 ] . Condensation of the aldehydic carbonyl group with methylamine yields the product t r a n s − [ P d C I { C ( = N C 6 H 4 O M e − p ) ︹ C H = N M e } ( P P h 3 ) 2 ] , DABII, with different substituents on the N-imino atoms. Substitution …
Insertion of isocyanides into the palladium-(2-pyridyl) bond
The reaction of the pyridyl-bridged binuclear complex [PdBr(μ-2-C5H4N)(PPh3)]2 with isocyynides CNR (R p-C6H4OMe, Me, C6H11) yields the complex PdBr{(&2.dbnd;NR)C(&2.dbnd;NR) (2-C5H4N)}(PPh3)] containing a C,N-chelated 1,2-bis(imino)-2-(2-pyridyl)ethyl group, which results from successive insertions of two isocyanides molecules into the palladium2-pyridyl bond. The mononuclear compound trans-[PdBr(2-C5H4N)(PMePh2)2] readily reacts with various CNR ligands (R p-C6H4OMe, Me, C6H11, CMe3) to give the imino(2-pyridyl)methylpalladium(II) derivatives, trans-[Pdbr{C(=NR)(2-C5H4N)} (PMePh2)2].