4‐Thiolatobenzoato‐Bridged Rhodium/Zirconium Complexes: 32‐Membered Metallamacrocycles and Their Linear Dinuclear Counterparts

The heterometallic dinuclear complex [Cp* 2 Zr(Me){(μ‐OOCC 6 H 4 S)Rh(PEt 3 ) 3 }] ( 3 ) is readily obtained by methane elimination in the reaction of [Rh(SC 6 H 4 COOH)(PEt 3 ) 3 ] with [Cp* 2 ZrMe 2 ] in a 1:1 ratio. Complex 3 reacts with 1 equiv. of water to give [Cp* 2 Zr(OH){(μ‐OOCC 6 H 4 S)Rh(PEt 3 ) 3 }] ( 4 ), a rare example of a terminal hydroxo complex of a zirconocene. Complexes 3 and 4 are isotypic. The influence of the zirconocene group on the properties of the rhodium complex was evaluated with 31 P NMR spectroscopy, cyclic voltammetry and DFT calculations. [Cp* 2 ZrMe 2 ] reacts with [{Rh(μ‐SC 6 H 4 COOH)(PPh 3 ) 2 } 2 ] (even in a 1:1 ratio at room temperature) or with [Rh(SC 6 H 4 COOH)(PEt 3 ) 3 ] (in a 1:2 ratio at elevated temperature) to give 32‐membered metallamacrocycles containing four rhodium and two zirconium atoms, in which each zirconocene group bridges two {Rh(SC 6 H 4 COO)(PR 3 ) 2 } 2 units [R = Ph ( 5 ), Et ( 6 )]. The only significant structural difference in 5 and 6 is the presence of two different isomers, in which the bridging thiolato ligands occupy either the exo or the endo position of the Rh 2 S 2 ring. However, this small difference has a significant influence on the size of the macrocyclic cavity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)