Group 12 metal complexes of tetradentate N2O2-Schiff-base ligands incorporating pyrazole -: Synthesis, characterisation and reactivity toward S-donors, N-donors, copper and tin acceptors

New [M(Q)(2)(X)] derivatives (where M=Zn, Cd or Hg; Q=1-phenyl-3-methyl-4-R(C=O)-pyrazolon-5-ato; in detail: Q(L), R=C6H5; Q(B), R=CH2C(CH3)(3); Q(S), R=CH(C6H5)(2); X=EtOH or H2O) have been synthesised and characterised. These compounds undergo a condensation reaction with the appropriate diamine in ethanol, affording novel Schiff-base metal derivatives [M(diaquo)bis(1-phenyl-3-methyl-4-R(C=N)-pyrazolone)(CH2)(n)diimmine] ((LH2)-H-n, R=C6H5, n=2, 3 or 4; (BH2)-H-n, R-CH2C(CH3)(3), n=2, 3 or 4; (SH2)-H-n, Cd-113 NMR study has R=CH(C6H5)(2), n=2 or 3; M=Zn, Cd or Hg). These compounds possess a six-coordinate metal environment. A been carried out on cadmium derivatives. The derivative [Zn(L-2)(H2O)(2)] reacted with CuCl2 and with Cu(CIO4)(2) affording [Cu(Q(L))(2)] and [Cu(en)(2)](ClO4)(2) (en=ethylendiamine), respectively, upon breaking of the C=N bond in the Schiff-base donor. In addition [Zn(L-2)(H2O)(2)] reacted with 1,10-phenanthroline (phen), yielding the derivative [Zn(Q(L))(2)(phen)]. Whereas when [Zn(L-2)(H2O)(2)] reacted with CdCl2, formation of [Cd(L-2)(H2O)(2)] due to exchange of the metal centre was observed. Finally the derivative [Zn(L-2)(Hmimt)], likely containing a five-coordinate ZnN2O2S central core, has been obtained from the exchange reaction between [Zn(L-2)(H2O)(2)] and 1-methylimidazolin-2-thione (Hmimt). (C) 1999 Elsevier Science Ltd. All rights reserved.