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

The heterometallic dinuclear complex [Cp*2Zr(Me){(μ‐OOCC6H4S)Rh(PEt3)3}] (3) is readily obtained by methane elimination in the reaction of [Rh(SC6H4COOH)(PEt3)3] with [Cp*2ZrMe2] in a 1:1 ratio. Complex 3 reacts with 1 equiv. of water to give [Cp*2Zr(OH){(μ‐OOCC6H4S)Rh(PEt3)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 31P NMR spectroscopy, cyclic voltammetry and DFT calculations. [Cp*2ZrMe2] reacts with [{Rh(μ‐SC6H4COOH)(PPh3)2}2] (even in a 1:1 ratio at room temperature) or with [Rh(SC6H4COOH)(PEt3)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(SC6H4COO)(PR3)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 Rh2S2 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)