Published: June 23, 2011 r2011 American Chemical Society 7189 dx.doi.org/10.1021/ic2007793 | Inorg. Chem. 2011, 50, 7189–7194 ARTICLE pubs.acs.org/IC Synthesis of Pd 3 Tl and Pd 6 Tl 2 Complexes Based on a Trinuclear ArylPalladium(II) Complex Acting as a Metallaligand Toward Thallium(I) Through TlArene and TlI Bonds Jos  e Vicente,* ,† Rashmi V. Shenoy, † Elo  isa Mart  inez-Viviente,* ,† and Peter G. Jones ‡ † Grupo de Qu  imica Organomet  alica, Departamento de Qu  imica Inorg  anica, Facultad de Qu  imica, Universidad de Murcia, E-30071, Murcia, Spain ‡ Institut f€ ur Anorganische und Analytische Chemie, Technische Universit € at Braunschweig, Postfach 3329, 38023, Braunschweig, Germany b S Supporting Information ’ INTRODUCTION Arylpalladium complexes have been extensively investigated because of their involvement in many important CC and Cheteroatom bond-forming reactions. 1 Suitable substituents ortho to Pd(II) may influence the reactivity of these complexes 2,3 or participate in formation of organic compounds. 4,5 We are trying to extend this chemistry to 1,3,5-tripalladated benzene derivatives with substituents ortho to each Pd. 6,7 Such complexes could have a huge potential for the Pd-mediated synthesis of organic polycyclic compounds. This is an almost unexplored field, with only three publications on 1,3,5-tripalladated arenes, two of them by our research group. 68 Even with other transition metals there are only three examples of 1,3,5-trinuclear derivatives (one Mn and two Fe complexes). 9 Tl(I) is known for its bewildering complexity of coordination numbers and geometries, 10 a nonstandard behavior often ascribed to relativistic effects arising from the 6s 2 lone pair. 11 It is able to form π complexes with aromatic hydrocarbons, as first proposed for η 5 -Cp ligands 12 and later for arenes. 13 Although not com- mon, Tl(I) π-arene complexes are now well documented in the literature, with both inter- and intramolecular interactions re- ported. 1416 However, there is no precedent for polynuclear heterobimetallic compounds based on Tl(I)arene interactions, as reported here. The closest example is a [Tl 2 {Fe(Cp 2 ) 3 }] com- plex with TlCp interactions. 15 In 2001 we published the synthesis of the trinuclear complex [(PdIL 2 ) 3 (μ-C 6 Me 3 -1,3,5)] (L 2 = 4,4 0 -di- tert-butyl-22 0 -bipyridine, 1) (Scheme 1), 6 prepared by oxidative addition of 1,3,5-triiodome- sitylene to 3 equiv of [Pd(dba) 2 ] (dba = dibenzylideneacetone) in the presence of L 2 . Very frequently, Tl(I) salts of weakly co- ordinating anions are used as halide-abstracting agents toward organopalladium halocomplexes, creating a coordination vacancy and promoting reactions such as ligand exchange, cyclopalladation, insertion of unsaturated molecules, rearrangement processes, or decomposition reactions. 3,4 We report here a quite different behavior when trying to replace I by OTf in complex 1. ’ RESULTS AND DISCUSSION Synthesis and Crystal Structures of 2 and 2&2. The reaction of complex 1 with 1 equiv of TlOTf in THF (Scheme 1) did not lead to a substitution product but to the unexpected formation of an adduct of stoichiometry 1:TlOTf (89% yield). Its X-ray crystal structure shows two different molecules in the unit cell, the monomer [{(PdIL 2 ) 3 (C 6 Me 3 -1,3,5)}Tl]OTf (2, Scheme 1 and Scheme 1 Received: April 15, 2011 ABSTRACT: The metallaligand [(PdIL 2 ) 3 (C 6 Me 3 -1,3,5)] (L 2 = 4,4 0 - di-tert-butyl-22 0 -bipyridine = tbbpy) reacts with TlOTf to afford the complex [{(PdIL 2 ) 3 C 6 Me 3 -1,3,5}Tl]OTf, which exists in the solid state as a 2:1 mixture of monomer and dimer, both showing Tl(I)I and Tl(I)η 6 -mesitylene bonds. In solution, only the monomer is observed. Heating of toluene solutions of [(PdIL 2 ) 3 (C 6 Me 3 -1,3,5)] affords the dinuclear complex [(PdIL 2 ) 2 (C 6 HMe 3 -1,3,5)].