COMPLEXES OF FUNCTIONALIZED PHOSPHINE-LIGANDS .1. COMPLEXES OF FE-III, CO-III, NI-II AND RE-V WITH TRIDENTATE SCHIFF-BASES HAVING PNO, NNO AND NNS DONOR SETS - CRYSTAL-STRUCTURES OF 2-(PH(2)PC(6)H(4)N=CH)C6H4OH AND [CO(2-(PH(2)PC(6)H(4)CH=N)C6H4O)(2)][PF6]

The Schiff bases 2-[Ph(2)P(CH2)(n)N=CH] C6H4OH (n = 3, HL(1) or 2 HL(2)), 2-(RCH=N)C6H3(OH)X-4 (R = 2-Ph(2)PC(6)H(4), X = H HL(3); R = 2-C5H4N, X = H HL(4); R = 2-C5H4N. X = Cl HL(5)) were synthesised from the appropriate amine and aldehyde. On deprotonation these all functioned as tridentate monoanionic ligands to give complexes [FeL(2)](+) and [CoL(2)]+ with Fe-III and Co-III and neutral complexes of stoichiometry NiL(2) with Ni-II. The iron complexes were examined by Mossbauer spectroscopy which indicated the presence of two iron sites in [FeL(2)(1)](+) with a spin-state equilibrium dependent on both temperature and the counter ion. The complex [FeL(2)(3)](+) showed a single iron site, again with a spin state dependent on counter ion and temperature. The crystal structures of HL(3) and [CoL(2)(3)](+) have been determined. The distortions in free HL(3) predispose it for co-ordination in a fac geometry to the Co with cis-PPh(2) groups, and the changes occurring on co-ordination are discussed in detail. Reaction of RCHO (R = 2-Ph(2)PC(6)H(4) or 2-C5H4N) with 2-aminobenzenethiol gave stable thiazoles RCHNHC(6)H(4)S-2 which did not ring open to give tridentate ligands even on reaction with base and/or metal ions.