Titanium(IV) complexes of the crystallographically characterised fluorene-Schiff base N-2-fluorenyl(salicylideneimine) and related bi- and tetradentate ligands

Abstract Schiff base ligands have been prepared by the condensation of 2-aminofluorene with salicylaldehyde ( 1 , flusalH) or 3-methoxy-2-hydroxybenzaldehyde ( 2 , MeOflusalH). Compound 1 reacts with TiCl 4 in a 1:1 stoichiometry to afford [TiCl 3 (flusal)] ( 3 ) and in a 2:1 ratio to yield [TiCl 4 (flusalH) 2 ] ( 4 ). The reaction of excess TiBz 4 with compound 1 results in the isolation of the octahedral Ti(IV) complex [Ti(flusal) 2 (flusalaBz) 2 ] ( 5 ). Crystallographic and spectroscopic data for the latter indicate a complex containing two Schiff base ligands present as conventional N,O chelates and a further two ligands in which the CN function is reduced by the addition of benzyl and hydrogen moieties producing an O-bound species with pendant amine. The single crystal X-ray diffraction structure of compound 1 has been obtained and compared with the published data for compound 5 . Similar ligand alkylation to that observed in compound 5 is also achieved by the reaction of organolithium reagents with compounds 1 and 2 ; the reaction of PhLi and compound 2 followed by aqueous hydrolysis affords MeOflusalaPhH ( 6 ). Although reactivity does occur between TiCl 4 and compound 6 , the products could not be fully characterised. Thus tetradentate reduced Schiff base ligands were synthesised by the reaction of salenH 2 with MeLi or PhLi, giving salenaMe 2 H 2 ( 7 ) and salenaPh 2 H 2 ( 8 ), respectively. Reaction of compound 8 and TiCl 4 affords the quadruply deprotonated amido complex [Ti(salenamidoPh 2 )] ( 9 ), which hydrolyses in air to the μ-oxo amine complex [Ti(salenaPh 2 )O] ( 10 ).