Dinuclear Zinc Complexes Supported by Macrobinucleating Hexaaza-Dithiophenolate Macrocycles: Synthesis of Zinc Thiolate Complexes with Biologically Relevant N3S and N2SCl Donor Sets

The ability of the macrocyclic hexaaza-dithiophenolate macrocycles (H2LH6, H2LMe2H4, and H2LMe6) to support dinuclear zinc complexes has been examined. The macrocyclces contain two 4-tert-butylthiophenolate units which are connected by two lateral dipropylenetriamine units with different nature and patterns (secondary or tertiary) of the N donors (H2LH6: 6 x R2NH, H2LMe2H4: 4 x R2NH, 2 x R2NMe, H2LMe6: 6 x R2NMe). Three binuclear complexes ([Zn-2(L-H6)](2+) (1), [Zn-2(L-Me2H4)](2+) (2), and [Zn2H2(L-Me6)Cl-2](2+) (3)) were obtained, isolated as ClO4- or BPh4 -salts, and characterized by CHN, ESI-MS, IR, and NMR spectroscopy, and X-ray crystallography (1(ClO4)(2), 1(BPh4)(2), 2(BPh4)(2), 3(ClO4)(2)). In contrast to the parent N6S2 macrocycles with diethylenetriamine linkers which support bioctahedral [Zn2L(L')](n+) complexes (L' = bridging coligand), the present ligands coordinate to zinc with non-bridging thiolato donors to afford tetrahedral ZnN3S (1,2) or ZnN2SCl (3) coordination environments. The decrease of the coordination number from 6 in the [Zn2L(L')](n+) to 4 in the present complexes is attributed to the change of the chelate-ring size. The six-membered chelate rings in 1-3 allow larger bond angles and encourage tetrahedral coordination.