Investigation of dimetallic and trimetallic complexes: Palladium and platinum precursor and sandwich complexes

The synthesis of a trimetallic, ditropylium complex has provided new avenues of research into understanding the interactions of the different components used in this novel sandwich complex.;The instability of zero valent metal centers makes the efficiency with which they are made an important and substantial issue. Palladium and platinum can both form eta, η, bonds with π-conjugated organic systems seen in dibenzylideneacetone, dba, and tropylium [C7H7] +. Substituted variations of the palladium and platinum complexed system with dba have been synthesized with the intention of investigating the effect of increasing the electron density within the olefinic double-bonds, as characterized by X-ray crystallography, and multinuclear nuclear magnetic resonance (NMR) and ultra-violet visible (UV-Vis) spectroscopy. The enhancement in electron density has changed the π back bonding that is present in the complexed dba system, possibly leading to more engineered precursor complexes capable of being synthesized in higher yields and acting as a more suitable precursor complex.;Other precursor complexes have been synthesized including [Pd2(MeCN) 6]2+, which could act as a useful adjunct to other complexes. The development of a secondary precursor complex that contains either two +1 metal center or one +2 metal center with a zero valent center has provided new opportunities to learn about the structure-property relationships in these organometallic systems. The zero valent metal centers can be combined to form a mixed metal complex with different qualities and characteristics, while the conjugated systems can be adjusted and expanded to coordinate more metal centers along with the equatorial ligands bonded to the metal centers as well.;Previous work in our group has thoroughly investigated the [Pd3 Tr2X3]− motif. The equatorial ligands can be exchanged with other ligands with an excess of electrons. The common substituents of chlorine, bromine and iodine represent a series of conjugate Lewis bases of strong acids. We have sought to increase the molecular diversity of this by taking advantage of this Lewis Acid-Base interaction. By introducing more conjugate bases of strong acids onto this [Pd3Tr 2]2+ system, several new complexes have been synthesized. The development of several new variations on the original synthesis parameters has enabled the synthesis of many of these new substituted systems, which have provided new insights into how the metal centers interact with different ligands.