Group 12 metal complexes of tetradentate N_2O_2-Schiff-base ligands incorporating pyrazole Synthesis, characterisation and reactivity toward S-donors, N-donors, copper and tin acceptors

摘要

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 = C_6H_5; Q_B, R = CH_2C(CH_3)_3; Q_s, R = CH(C_6H_5)_2; X = EtOH or H_2O) 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-3methyl-4-R(C = N)-pyrazolone)(CH_2)_n diimmine] (L~nH_2, R = C_6H_5, n = 2, 3 or 4: B~nH_2, R = CH_2C(CH_3)_3), n = 2, 3 or 4; S~nH_2, R = CH(C_6H_5)_2 n = 2 or 3; M = Zn, Cd or Hg. These compounds possess a six-coordinate metal environment. A ~(113)Cd NMR study has been carried out on cadmium derivatives. The derivative [Zn(L~2)(H_2O)_2] reacted with CuCl_2 and with Cu(ClO_4)_2 affording [Cu(Q_L)_2] and [Cu(en)_2](ClO_4)_2 (en = ethylendiamine), respectively, upon breaking of the C = N bond in the Schiff-base donor. In addition [Zn(L~2)(H_2O)_2] reacted with 1, 10-phenanthroline (phen), yielding the derivative [Zn(Q_L)_2(phen)]. Whereas when [Zn(L~2)(H_2O)_2] reacted with CdCl_2, formation of [Cd(L~2)(H_2O)_2] due to exchange of the metal centre was observed. Finally the derivative [Zn(L~2)(Hmimt)], likely containing a five-coordinate ZnN_2O_2S central core, has been obtained from the exchange reaction between [Zn(L~2)(H_2O)_2] and 1-methylimidazolin-2-thione (Hmimt).