Bitopic Phenylene-Linked Bis(pyrazolyl)methane Ligands: Preparation and Supramolecular Structures of Hetero- and Homobimetallic Complexes Incorporating Organoplatinum(II) and Tricarbonylrhenium(I) Centers

The new fixed-geometry, phenylene-linked bis(pyrazolyl)methane ligands α,α,α‘,α‘-tetra(1-pyrazolyl)-m-xylene (m-[CH(pz)2]2C6H4, Lm), α,α,α‘,α‘-tetra(1-pyrazolyl)-p-xylene (p-[CH(pz)2]2C6H4, Lp), and α,α,α‘,α‘-tetrakis(4-benzylpyrazol-1-yl)-p-xylene (p-[CH(4Bnpz)2]2C6H4,
4BnLp) have been synthesized in order to prepare hetero- and homobimetallic complexes
incorporating tricarbonylrhenium(I) and bis(p-tolyl)platinum(II) fragments. Coordination of
one rhenium center to Lm was achieved to yield the monometallic rhenium complex {m-[CH(pz)2]2C6H4}Re(CO)3Br, which then incorporated a second metal center to give the heterobimetallic complex {μ-m-[CH(pz)2]2C6H4}[Re(CO)3Br][Pt(p-tolyl)2]. The homobimetallic rhenium complexes of each ligand, {μ-m-[CH(pz)2]2C6H4}[Re(CO)3Br]2, {μ-p-[CH(pz)2]2C6H4}[Re(CO)3Br]2, and {μ-p-[CH(4Bnpz)2]2C6H4}[Re(CO)3Br]2, were also prepared. The crystalline
structure of each complex shows extensive noncovalent interactions, including weak hydrogen
bonds and π···π and CH···π interactions, that organize the molecules into complex supramolecular structures.