Coupling dirhodium units through terpyridine bridges: synthesis and structure of a novel molecular rectangle

The cation [Rh<SUB>2</SUB>(μ-O<SUB>2</SUB>CMe)<SUB>2</SUB>(MeCN)<SUB>6</SUB>]<SUP>2+</SUP> reacts with the bis-terpyridine ligand 2,3,5,6-tetra-2-pyridylpyrazine (tppz) to yield the reduced compound [Rh<SUB>4</SUB>(μ-O<SUB>2</SUB>CMe)<SUB>2</SUB>(tppz)<SUB>2</SUB>(MeOH)<SUB>4</SUB>]<SUP>4+</SUP> whose structure is that of molecular rectangle with edges defined by short Rh–Rh and long Rh–tppz–Rh units