N,N'-ethylenebis(salicylideneiminato) transition metal ion chelates

1:1 Addition complexes of [NiIIL]·H2O [H2L =N,N′-bis(3-methoxysalicylidene)ethylenediamine (3MeO-H2salen), N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine (3MeO-H2salpn) or N,N′-bis(3-methoxysalicylidene)-o-phenylenediamine (3O-H2salphen)] with SnR2Cl2(R = Me or Ph), SnBunCl3, or SnCl4 have been found to be generally monoaqua adducts of the tin Lewis acids with the water engaged in hydrogen bonding with the methoxy and phenolic oxygen atoms of the Schiffbase ligand. Both water and methoxy oxygen atoms are involved in donor-bond formation to tin in the polymeric structures 2SnMe2Cl2·[Ni(3MeO-salen)]·H2O and SnMe2Cl2·[Ni(3MeO-salphen)]·H2O, each of which has two very different tin environments. The two octahedral tin sites in the structure of SnMe2Cl2·2[Ni(3MeO-salphen)·H2O] appear to result from two isomeric forms of the adduct co-existing in a lattice as a result of hydrogen-bonding interactions. Crystal-structure determinations revealed that the monoaqua adducts of dimethyltin dichloride which exist in the structures SnMe2Cl2·[Ni(3MeO-salen)]·H2O and SnMe2Cl2·[Ni(3MeO-salon)]·H2O differ in that, in the former tin is in a trigonal-bipyramidal environment, whereas in the latter it is in an octahedral environment as a result of an intermolecular Sn ⋯ Cl contact of 3.615 A.

Transition-metal Schiff-base complexes as ligands in tin chemistry. Part 3. An X-ray crystallographic and tin-119 Mössbauer spectroscopic study of adduct formation between tin(IV) Lewis acids and nickel 3-methoxysalicylaldimine complexes

A new mixed Schiff base N , N ′-ethylenemono(3-carboxysalicylideneimine)mono(salicylideneimine) has been synthesized by the condensation of equimolar quantities of ethylenediamine, salicylaldehyde and 3-formylsalicylic acid. A polymer supported Schiff base (PS–CH 2 –LH 2 ) has been synthesized by the reaction of chloromethylated polystyrene (containing 3.9 mmol of chlorine per g of resin and 2% cross-linked with divinylbenzene) and the Schiff base N , N ′-ethylenemono(3-carboxysalicylideneimine)mono(salicylideneimine). The polymer-anchored Schiff base reacts with metal salt/metal complex and forms polymer-anchored complexes having the formulae PS–CH 2 –LCu, PS–CH 2 –LNi, PS–CH 2 –LCo, PS–CH 2 –LFeCl·DMF, PS–CH 2 –LZn, PS–CH 2 –LCd, PS–CH 2 –LMoO 2 and PS–CH 2 –LUO 2 . The polymer-anchored complexes have been characterized on the basis of elemental analysis, infrared and electronic spectra and magnetic susceptibility measurements. The shifts of the ν (CN) (azomethine) stretch to lower energy and ν (CO) (carboxylic) to higher energy in the polymer-anchored complexes indicate the ONNO donor behaviour of the chelating resin. The metal ions in the metal bound polymers can be leached by hot dilute formic acid, acetic acid or hydrochloric acid. The coordinated dimethylformamide is completely lost on heating the complexes in air. The complexes PS–CH 2 –LCu and PS–CH 2 –LCo are paramagnetic with square planar structure, PS–CH 2 –LNi is diamagnetic with square planar structure and PS–CH 2 –LFeCl·DMF is paramagnetic and octahedral, PS–CH 2 –LZn and PS–CH 2 –LCd are diamagnetic and tetrahedral, PS–CH 2 –LMoO 2 and PS–CH 2 –LUO 2 are diamagnetic and have octahedral structure. The stoichiometry and the structure of the metal bound polymers are comparable with those of metal complexes of N , N ′-ethylenebis(salicylideneimine). This is the first report of the syntheses of a mixed Schiff base and its coordination complexes.

Syntheses and characterization of a chelating resin containing ONNO donor quadridentate Schiff base and its coordination complexes with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), cadmium(II), molybdenum(VI) and uranium(VI),

Synthesis and characterization of organotin(IV) compounds with Schiff base of o-vanillin-2-thiophenoylhydrazone

1 : 1 Adducts have been formed between SnMe2(NCS)2 and SnBun2(NCS)2 with [Ni(3MeO-salpd)]·H2O [3MeO-H2salpd =N,N′-bis(3-methoxysalicylidene)propane-1.3-diamine] and [Ni(3MeO-salbn)]·H2O [3MeO-H2salbn =N,N′-bis(3-methoxysalicylidene)butane-1,4-diamine] and are best represented as the intimate ion-paired adducts [SnR2]2+·[NiL(NCS)2]2–[L = Schiff-base ligand; R = Me or Bun] in each of which the tin atom sits in the plane of, and is held by donor bonds from, the four Schiff-base oxygen atoms. A crystal-structure determination of [SnMe2]2+·[Ni(3MeO-salpd)(NCS)2]2– revealed a tin co-ordination geometry which can be described as skew trapezoidal bipyramidal. The large unoccupied volume of the tin co-ordination sphere results in tin readily increasing its co-ordination number to seven, as demonstrated crystallographically in [SnMe2·dmf]2+·[Ni(3MeO-salpd)(NCS)2]2+(dmf = dimethyl-formamide), which contains tin in a pentagonal-bipyramidal co-ordination environment with trans methyl groups and five donor oxygen atoms in the equatorial plane. X-Ray structural studies of both [SnBun2]2+·[Ni(3MeO-salpd)(NCS)2]2– and [SnBun2]2+·[Ni(3MeO-salbn)(NCS)2]2– revealed the presence of molecular association resulting from weak intermolecular thiocyanate contacts, thus providing each tin with pseudo-pentagonal-bipyramidal co-ordination geometry. These latter adducts readily formed tin donor bonds with dmf. The 1:1 adduct formed between SnPh2(NCS)2 and [Ni(3MeO-salpd)]·H2O was shown, from an X-ray crystallographic study, to be the intimate ion-paired heterobimetallic complex [SnPh2(NCS)]+·[Ni(3MeO-salpd)(NCS)(MeCN)]– in which tin has pentagonal-bipyramidal geometry with trans phenyl groups. Infrared and tin-119 Mossbauer spectroscopic data clearly demonstrate that a similar pentagonal-bipyramidal co-ordination geometry exists about tin in the complexes [SnR2(NCS)]+·[ML(NCS)]–·nH2O (R = Me or Bun; M = Cu or Zn; n= 0, 1 or 2).

Transition-metal Schiff-base complexes as ligands in tin chemistry. Part 5. Structural studies of intimate ion-paired heterobimetallic complexes of tin(IV) and nickel, copper or zinc with 3-methoxysalicylaldimine ligands

The planar transition metal compounds NN′-ethylenebis(salicylideneaminato)metal(II)[MII(salen)] where the metal ion is cobalt(II), nickel(II), or copper(II), react with the halides SnX4 and SnX2(where X = Cl or Br) to form 1 : 1 adducts Characterisation of these adducts using magnetic data, and diffuse reflectance and ir spectroscopy indicates a retention of planarity about the transition-metal ion Structures are suggested for the adducts A mechanism is put forward to explain the metal-exchange reaction observed in polar solvents for the adducts CoII(salen)SnX4, leading to the compounds SnX2(salen)

M. D. Hobday

Papers

Reaction of tin(IV) and tin(II) halides with transition-metal ion Schiff-base complexes