Synthesis and Structural Characterization of a New Heterobimetallic Coordination Complex of Barium and Cobalt for Use as a Precursor for Chemical Vapor Deposition Asif A. Tahir, ² Kieran C. Molloy, ‡ Muhammad Mazhar,* ,² Gabriele Kociok-Ko 1 hn, ‡ Mazhar Hamid, ² and Sarim Dastgir ² Department of Chemistry, Quaid-I-Azam UniVersity, Islamabad 45320, Pakistan, and Department of Chemistry, UniVersity of Bath, ClaVerton Down, Bath, BA2 7AY UK Received April 12, 2005 Ba(dmae) 2 (dmaeH ) N,N-dimethylaminoethanol, C 4 H 11 NO) reacts with Co(acac) 2 (acac ) 2,4-pentanedionate) to produce the trinuclear coordination complex [Ba 2 Co(acac) 4 (dmae) 3 (dmaeH)] in an 85% yield. Spectroscopic and single-crystal X-ray diffraction experiments indicate that the complex possesses a structure in which two barium atoms and a cobalt atom are bridged by acac and dmae groups. The barium centers are eight and nine coordinate with BaO 7 N and BaO 7 N 2 coordination spheres while the cobalt is a more regular CoO 5 N octahedron. This 2:1 heterobimetallic molecular complex was investigated as precursor for the deposition of thin film by AACVD. The film was characterized by SEM and XRD. TGA shows that the complex starts thermal decomposition upon heating in nitrogen atmosphere at 105 °C to produce barium cobalt oxide material of a Ba 2 CoO 3 composition with an orthorhombic structure. The synthetic approach detailed here represents a unique route to the formation of a heterobimetallic barium cobalt coordination complex. Introduction There has been considerable interest in recent years in the development of new precursors for chemical vapor deposition (CVD) of ceramic materials. In general, such precursors must be volatile, have sufficient stability for the transportation to the deposition site, and decompose cleanly to give the desired materials. Various acetylacetone and alkoxide complexes 1 of both main group and transition metals have been used to deposit thin films of metals and metal oxides. 2,3 Much of the more recent focus in this area has been the synthesis of hetrobimetallic, metallorganic precursors, 4 which have be- come a cornerstone of advances in new materials. Single- source bimetallic compounds, which deliver both elements of a final material simultaneously, can generate complex ceramic materials in a single step, removing the need to match the reaction rates required of a multicomponent precursor mixture. 5 Typical examples, among many pos- sibilities, are the deposition of SrTa 2 O 6 and SrNb 2 O 6 directly from [SrTa 2 (OEt) 10 (dmae) 2 ] 6 and [SrNb 2 (OEt) 8 (µ-OEt) 2 (µ 2 - dmae) 2 ], 7 respectively ([dmaeH ) N,N-dimethylaminoethanol HOCH 2 CH 2 N(CH 3 ) 2 ]). The wide interest in cobalt oxide with main group metal oxides is a result of their applications in solid-state fuel cells 8 and cobalt-based superconductors 9 and the potential applica- tions of La 1-x Sr x CoO 3 and Ba 1-x Sr x CoO 3 as gas and ion sensors 10,11 in electrodes and ferroelectric capacitors. 12 Ba- * To whom correspondence should be addressed. E-mail: mazhar42pk@ yahoo.com. ² Quaid-I-Azam University. ‡ University of Bath. (1) Mehrotra, R. C.; Singh, A.; Sogani, A. Chem. ReV. 1994, 94, 1643- 1660. (2) Berry, A. D.; Gaskill, D. K.; Holm, R. T.; Cukauskas, E. J.; Kaplan, R.; Henry, R. L. Appl. Phys. Lett. 1988, 52 (20), 1743-1745. (3) Panson, A. J.; Charles, R. G.; Schmidt, D. N.; Szedon, J. R.; Machiko, G. J.; Braginski, A. I. Appl. Phys. Lett. 1988, 53 (18), 1756-1758. (4) Hubert-Pfalzgraf, L. G. Inorg. Chem. Commun. 2003, 6, 102-120. (5) Jones, A. C. J. Mater. Chem. 2002, 12, 2576-2590. (6) Crosbie, M. J.; Wright, P. J.; Jones, A. C.; Leedham, T. J.; Brien, P. O.; Critchlow, G. W. Chem. Vap. Deposition 1999, 5,9-12. (7) Jones, A. C.; Tobin, L. N.; Marshall, P. A.; Potter, J. R.; Chalker, R. P.; Bickley, F. J.; Davies, O. H.; Smith, M. L.; Critchlow, G. W. J. Mater. Chem. 2004, 14, 887-894 (8) Ishihara, T.; Fukui, S.; Nishiguchi, H.; Takita, Y. J. Electrochem. Soc. 2002, 149 (7), 823-828. (9) Takada, K.; Sakurai, H.; Takayama-Muromachi, E.; Lzumi, F.; Dilanian, R.; Sasaki, T. Nature 2003, 422, 53-55. (10) Brosha, E. R.; Mukundan, R.; Brown, D. R.; Garzon, F. H.; Visser, J. H.; Zanini, M.; Zhou, Z.; Logothetis, E. M. Sens. Actuators B 2000, 69, 171-182. (11) Shimixu, Y.; Ishikawa, A.; Iseki, K.; Takase, S. J. Electrochem. Soc. 2000, 147, 3931-3934. Inorg. Chem. 2005, 44, 9207-9212 10.1021/ic050564+ CCC: $30.25 © 2005 American Chemical Society Inorganic Chemistry, Vol. 44, No. 25, 2005 9207 Published on Web 11/11/2005