Glycol modified cis-diisopropoxy-bis( N-phenylsalicylideneiminato) titanium(IV). Syntheses, characterization, X-ray structures of Ti{O(C 6H 4)CH [dbnd]NPh} 2(OPr i) 2, [{Ti(O(C 6H 4)CH [dbnd]NPh) 2}O] 3 and their low temperature transformation to pure grains of nanosized titania

Abstract

Ti(OPr i ) 4 reacts with N-phenylsalicylideneimine in anhydrous benzene in 1:2 molar ratio to afford precursor [Ti{O(C 6H 4)CH NPh} 2{OPr i } 2] ( A). Further reactions of A with various glycols yield heteroleptic complexes of the type [Ti{O(C 6H 4)CH NPh} 2{O–G–O}] [where –G– = (CH 2) 2 ( 1), (CH 2CHCH 3) ( 2), (CH 3CHCHCH 3) ( 3), (CH 2CHC 2H 5) ( 4), C(CH 3) 2C(CH 3) 2 ( 5), (CH 2) 3 ( 6), (CH 2CH 2CHCH 3) ( 7), (CH 3) 2CCH 2CHCH 3 ( 8), (CH 2) 5 ( 9) and (CH 2) 6 ( 10)]. FAB mass spectroscopic studies of some of the derivatives suggest their monomeric nature. Single crystal X-ray diffraction study of A reveals cis-orientation of the isopropoxy groups [O(3)–Ti(1)–O(4) = 102.23(11)°] and distorted octahedral geometry around the titanium atom. Crystal structure of a trinuclear titanoxane [{Ti(O(C 6H 4)CH NPh) 2}O] 3, obtained from the partial hydrolysis of A, exhibit the formation of a six-membered Ti 3O 3ring. Complete hydrolysis and low temperature (300–500 °C) transformation of precursor A, as well as of 1 and 7 to pure TiO 2 have also been achieved using sol–gel technique. The XRD patterns indicate formation of anatase phase of TiO 2. The XRD and SEM observations on all the three samples indicate the formation of pure grains of nanosized titania. TGA curves of A and 7 suggest occurrence of multiple large thermal events.