Metal Complexes as Ligands IV

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Bi- and Tri- nuclear complexes derived from metal complexes of tetradentate salicylaldimines


The detailed synthesis is reported for a series of bi- and tri- nuclear complexes formed by using the donor properties of the two cis-oxygen atoms in metal (M) complexes of tetradentate Shiff bases (TSB) derived from salicylaldehyde or o-hydroxyacetophenone. The “complex ligands” [MTSB, M Cu(II), NiU(II) or Zn(II)] readily react with metal halides M′X 2[M′ Cu(II) or Zn(II)] or metal perchlorates M′(ClO 4) n [M′ Cu(II), Ni(II), Fe(II), Al(III), Mg(II), Ca(II), Sr(II), Ba(II), Na(I), or Ag(I) to form the complexes of the general types [MTSB) M′X 2] and M′(MTSB) 2(ClO 4) n, many of which are hydrated. The low magnetic moments of a number of the compounds are due to an antiferromaagnetic interactions between the metals. While a number of complexes of type [(MTSB)M′X n] have previously been reported to be non-ionic, the complexes M′(MTSB) 2(ClO 4) n are found to have the expected electrical conductivities in nitrobenzene solution. A systematic trend in the magnetic moments and spectral absorptions of the complexes CuTSB is due to an increased steric distortion from a planar towards a pseudo-tetrahedral environment about the copper atom as the length of the carbon chain(R) joining the adjacent nitgrogen atoms in TSB(-O...N-R-N....O-) increases. The spectra indicate that the chlorine bonded copper atom in [(CuTSB)(CuCl 2 complexes becomes increasingly distorted from a planar towards a tetrahedral configuration as the copper inside the CuTSB distorts the same way, up to a point where the approach of the two pseudo-tetrahedral copper atoms would be too close. As expected, this distortion appears to be slightly greater when bromine atoms are substituted for chlorine atoms in such compounds. In a given [CuTSB)CuCl 2 or M′(CuTSB) 2(ClO 4) n·xH 2O complex, the copper atom inside the CuTSB appears to be considerably closer to planar stereochemistry than it is the free CuTSB. It is concluded that the stereochemistries of the metals in the mono-, bi-, and tri-nuclear complexes are due to, and to a large extent predictable from, the steric requirements of the ligands and metals. Some i.r. spectra of MTSB and the bi- and tri-nuclear derivatives are reported, and earlier assignments of absorptions in the complexes MTSB are re-examined. © 1968.



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© 1968 Elsevier, All rights reserved.