Synthesis and Characterization of Pentanuclear Complexes Composed of Pairs of Macrocyclic Ni 2 L and Zn 2 L Complexes Linked by cis ‐[PtCl 2 (dppba) 2 ] and trans ‐[RhCl(CO)(dppba) 2 ] [dppba = (4‐Diphenylphosphanyl)benzoate, L = Macrocyclic Ligand]

The ability of the square‐planar complexes cis ‐[PtCl 2 (Hdppba) 2 ] ( 4 ) and trans ‐[RhCl(CO)(Hdppba) 2 ] ( 5 ), where Hdppba represents 4‐(diphenylphosphanyl)benzoic acid to act as bridging metalloligand for dinuclear macrocyclic [Ni 2 L] 2+ and [Zn 2 L] 2+ complexes is demonstrated (L 2– is a 24‐membered hexaazadithiophenolate macrocycle). Pentanuclear Ni 4 Pt and Zn 4 Pt complexes of composition [( M 2 L) 2 (μ‐dppba) 2 PtCl 2 ] 2+ [ M = Ni ( 7a ) or Zn ( 8a )] could be obtained either from substitution reactions between 4 and the corresponding [ M 2 L(μ‐Cl)] + compounds ( M = Ni, Zn) or by treatment of [PtCl 2 (NCMe) 2 ] with the [ M 2 L(μ‐dppba)] + complexes ( M = Ni, Zn). The pentanuclear Ni 4 Rh and Zn 4 Rh complexes of composition [( M 2 L) 2 (μ‐dppba) 2 RhCl(CO)] 2+ [ M = Ni ( 9a ) or Zn ( 10a )] were obtained by treatment of [Rh 2 Cl 2 (CO) 4 ] with the [ M 2 L(μ‐dppba)] + complexes. The new complexes were characterized by elemental analyses, ESI mass spectrometry, IR and UV/Vis spectroscopy, and by 1 H, 13 C, and 31 P NMR (for Zn). The Pt and Rh dppba complexes in 7a – 10a act in all cases as quadridentate bridging ligands linking two bioctahedral LNi 2 (or LZn 2 ) units by μ 1, 3 ‐bridging carboxylate functions. The 31 P chemical shifts and the 1 J (P, Pt) and 1 J (P, Rh) coupling constants further show that the cis and trans stereochemistry of the mononuclear starting materials 4 and 5 is maintained in the pentanuclear products. It is also demonstrated that the terminal Cl – ligands can be substituted by Br – and I – without affecting the pentanuclear nature of the complexes.