Complexes of Functionalised Phosphine Ligands. Part 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-(Ph2PC6H4N=CH)C6H4OH and 2>

Article abstract of DOI:10.1039/DT9940003553

The Schiff bases 2-C6H4OH (n = 3, HL¹ or 2 HL²), 2-(RCH=N)C6H3(OH)X-4 (R = 2-Ph2PC6H4, X = H HL³; R = 2-C5H4N, X = H HL⁴; R = 2-C5H4N, X = Cl HL⁵) were synthesised from the appropriate amine and aldehyde.On deprotonation these all functioned as tridentate monoanionic ligands to give complexes (1+) and (1+) with Fe(III) and Co(III) and neutral complexes of stoichiometry NiL2 with Ni(II).The iron complexes were examined by Moessbauer spectroscopy which indicated the presence of two iron sites in 12>(1+) with a spin-state equilibrium dependent on both temperature and the counter ion.The complex 32>(1+) showed a single iron site, again with a spin state dependent on counter ion and temperature.The crystal structures of HL³ and 32>(1+) have been determined.The distortions in free HL³ predispose it for co-ordination in a fac geometry to the Co with cis-PPh2 groups, and the changes occurring on co-ordination are discussed in detail.Reaction of RCHO (R = 2-Ph2PC6H4 or 2-C5H4N) with 2-aminobenzenethiol gave stable thiazoles which did not ring open to give tridentate ligands even on reaction with base and/or metal ions.