Formation of Trinuclear Palladium Orthometalated Complexes with Unprecedented Asymmetrical (μ 3 -S)(μ 3 -X) Bridges (X ) OH, SR, O 2 CR) from μ 2 -Hydroxo Dimeric Complexes and CS 2 † Pablo Espinet,* Celia Herna ´ndez, Jose ´ M. Martı ´n-Alvarez, and Jesu ´s A. Miguel Departamento de Quı ´mica Inorga ´ nica, Facultad de Ciencias, UniVersidad de Valladolid, 47005 Valladolid, Spain Received September 19, 2003 Complexes [Pd 3 (µ 3 -S)(µ 3 -X)(L) 3 ] (L ) orthometalated imine), obtained by an unusual reaction of µ 2 -OH dimeric complexes and CS 2 , are an unprecedented type of asymmetrical bridges between metallatriangles, which force an all-cis arrangement of the three orthometalated ligands relative to the metallatriangle. The reactivity of binuclear compounds [Pd(µ-OH)L n ] 2 HL n ) p-C n H 2n+1 O-C 6 H 4 -CHdN-C 6 H 4 -OC n H 2n+1 -p (n ) 2, 6, and 10) toward protic substrates such as amines, thiols, and carboxylic acids provides a versatile entry to mesomor- phic binuclear complexes (metallomesogens) with other bridges, and to mesomorphic mononuclear N,N-dialkyl- dithio-carbamate complexes by reaction with dialkylamines in the presence of carbon disulfide. 1 The change in molecular shape from dinuclear to mononuclear metallomesogens produces a noticeable lowering of transition temperatures, as expected from the less favorable molecular shape of the latter. 2 Pursuing our interest in novel structures to add to the still limited types of metallomesogenic materials, it was planned that the reaction of the µ-hydroxo complexes with alcohols and CS 2 might afford mononuclear xanthate com- plexes. 3 The outcome of the study was quite different. When [Pd(µ-OH)L 10 ] 2 (1a, Scheme 1) in CH 2 Cl 2 was treated with 2 molar equiv of octanol and carbon disulfide at 35 °C for 7 h, a yellow compound 2a was obtained. The 1 H NMR spectrum of 2a showed (a) the absence of octanyloxy chains; (b) only one set of 1 H resonances for the orthometalated imine ligand; and (c) a singlet at -2.55 ppm (with intensity 1 for 3 imines) which might be due to the presence of a µ-OH group. A very weak absorption in the IR at ca. 3622 cm -1 was in the expected range for ν(OH). Good quality crystals suitable for a full X-ray analysis could not be obtained for this complex with long aliphatic chains, nor for its analogue 2b with L 2 , but partial resolution of poor quality crystals for 2b revealed the existence of a Pd 3 core with two bridging ligands which, according to the elemental analysis C,H,N,S and the IR and 1 H NMR spectra, are assigned one S and one OH group, as shown in Scheme 1. The structure of 2 is further supported by those found for two derivatives (3b and 4b). The hydroxo ligand of complexes 2 is easily replaced when treated with some Bro ¨nsted acids. Thus, treatment of 2b with HSC 4 H 9 (molar ratio 1:1) afforded the trinuclear complex [Pd 3 (µ 3 -S)(µ 3 - SC 4 H 9 )(L 2 ) 3 ](3b), with mixed sulfide-thiolato bridges. The 1 H NMR resonances of the orthopalladated imine ligand in 3b indicate a cis arrangement of the three imines. The upfield shift of the methylene groups of the SC 4 H 9 chain is consistent with the thiolato group being cis to the imine nitrogens. 4 The X-ray structure of 3b was determined (Figure 1). 5 The * E-mail: espinet@qi.uva.es. † Dedicated to Professor J. Vicente on the occasion of his 60th birthday. (1) Dı ´ez, L.; Espinet, P.; Miguel, J. A. J. Chem. Soc., Dalton Trans. 2001, 1189. (2) Baena, M. J.; Espinet, P.; Ros, M. B.; Serrano, J. L. Angew. Chem., Int. Ed. Engl. 1991, 30, 711. (3) Lo ´ pez, G.; Sa ´nchez, G.; Garcı ´a, G.; Garcı ´a, J.; Sanmartı ´n, A.; Santana, M. D. Polyhedron 1991, 10, 2821. (4) Buey, J.; Dı ´ez, L.; Espinet, P.; Kitzerow, H. S.; Miguel, J. A. Chem. Mater. 1996, 8, 2375. (5) Crystal data for 3b‚2CH2Cl2: C57H67Cl4N3O6Pd3S2, M ) 1415.26, triclinic, space group P1 h, a ) 13.630(10) Å, b ) 14.167(11) Å, c )16.393(12) Å, R) 80.885(15)°,  ) 82.382(15)°, γ ) 78.950(14)°, V ) 3050(4) Å 3 , Z ) 2, R1 ) 0.0578, wR2 ) 0.1700. CCDC-211688. Scheme 1 Inorg. Chem. 2004, 43, 843-845 10.1021/ic0351085 CCC: $27.50 © 2004 American Chemical Society Inorganic Chemistry, Vol. 43, No. 3, 2004 843 Published on Web 01/20/2004