The reaction of iron carboxylates with titanium alkoxides. Isolation and structural characterisation of [Ti 6 (m 3 -O) 6 (O 2 CPh) 6 (OCH 2 C(CH 3 ) 3 ) 6 ] Paul S. Ammala, Stuart R. Batten, Christopher M. Kepert, Leone Spiccia *, Adrian M. van den Bergen, Bruce O. West School of Chemistry, P.O. Box 23, Monash University, Victoria 3800, Australia Received 19 October 2002; accepted 21 March 2003 Abstract The reaction of [Fe 4 (m 3 -O) 2 (O 2 CPh) 8 (py) 2 ](1) with Ti(OPr n ) 4 in toluene yields separate Fe and Ti species each containing both carboxylate and alkoxide groups rather than a bimetallic Fe Ã/Ti complex. The addition of neopentanol to the reaction mixture has enabled [Ti 6 (m 3 -O) 6 (O 2 CPh) 6 (OCH 2 C(CH 3 ) 3 ) 6 ](3) to be isolated and structurally identified. The compound [Ti 6 (m 3 -O) 4 (O 2 C- Ph) 8 (OPr n ) 8 ](4) has also been characterised and shown not to convert to a {Ti 6 (m 3 -O) 6 } 12 core compound under the same temperature conditions used in the Fe à /Ti reactions. # 2003 Elsevier B.V. All rights reserved. Keywords: Fe carboxylates; Ti alkoxides; Hexanuclear Ti-oxo-carboxylato-alkoxide; X-ray structures 1. Introduction Mixed oxides of Fe à /Ti have shown potential as counter-electrodes for use in electrochemical ‘smart windows’ [1] and as catalysts in the photochemical decomposition of water [2], while mixed oxides of Fe à / Zr are useful in the preparation of ‘stabilized’ zirconia [3]. The synthesis of such mixed oxides by sol  /gel processes would be aided by the use of suitable mixed metal compounds involving alkoxide and carboxylate groups. We have recently described the synthesis and structure of such an Fe à /Zr-carboxylate-alkoxide [Fe 2 Zr 2 (m 3 - O) 2 (m-O 2 CPh) 6 (OBu t ) 4 (py) 2 ] [4], formed by reaction in toluene between Zr(OBu t ) 4 and an Fe(III) oxo-carbox- ylate compound (1). Compound (1) was prepared by reaction of excess pyridine with [Fe 3 (m 3 -O)- (O 2 CPh) 6 (H 2 O) 3 ](O 2 CPh) and initially allotted the em- pirical formula [Fe 3 (m 3 -O)(O 2 CPh) 6 (py) 2 (H 2 O)](O 2 CPh) on the basis of analytical data only [5]. It was not structurally characterised, but has subsequently been shown to have magnetic and Mo ¨ ssbauer spectral properties more in agreement with the tetranuclear formula [Fe 4 (m 3 -O) 2 (O 2 CPh) 8 (py) 2 ](1) [4], the C, H, N analytical data being comparable for both formulations. A similar reaction involving (1) and Ti(OPr n ) 4 did not yield an isolable Fe à /Ti complex but gave separate Fe and Ti compounds presumably formed by group exchange between the Fe and Ti reagents. A brief mention of these observations identifying the Ti product as a {Ti 6 (m-O) 6 } 12 core compound was made in an earlier communication [5]. It was also then reported that reaction between [Fe 3 (m 3 -O)(O 2 CPh) 6 (H 2 O) 3 ](O 2 CPh)) and Ti(OPr n ) 4 in n -propanol allowed isolation and identification [5] of the known polynuclear Fe species [Fe 11 (m-O) 6 (m-OH) 6 (O 2 CPh) 15 ] [6] as a toluene adduct. The present paper presents details of the characterisa- tion of the {Ti 6 O 6 } 12 core compound. * Corresponding author. Tel.:  /61-3-9905 4526; fax:  /61-3-9905 4597. E-mail address: leone.spiccia@sci.monash.edu.au (L. Spiccia). Inorganica Chimica Acta 353 (2003) 75  /81 www.elsevier.com/locate/ica 0020-1693/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0020-1693(03)00242-1