A {Cu 4 I 4 } Cluster Supported on a Metal‐Dithiolato Complex Anion Causes its Conformational Change Leading to a Doubly‐Bridged Curved Coordination Polymer and its Reactivity with a Diamine Resulting in the Emergence of a [M(diamine)(dithiolate)] System

When dithiolene‐based coordination complexes [Bu 4 N] 2 [M II (tdas) 2 ] (tdas 2– = 1,2,5‐thiadiazole‐3,4‐dithiolate; M = Ni, Pd, Pt) are reacted separately with CuI, it results in the formation of chain‐like coordination polymers [Bu 4 N] 2 n [M II (tdas) 2 Cu 4 I 4 ] n [M = Ni (compound 1 ), Pd (compound 2 ), Pt (compound 3 )] in which each metal(bis)dithiolato complex unit supports a {Cu I 4 I 4 } cluster unit. Two of the crystal structures and powder X‐ray diffraction studies confirm that compounds 1 , 2 and 3 are isomorphous with each other showing the abundance of a doubly‐bridged “curved” chain‐like structure formed by the coordination of two “N” donor atoms of each [M II (tdas) 2 ] 2– complex unit to two Cu + ions of two adjacent {Cu I 4 I 4 } cluster units and by the coordination of two Cu + ions of a {Cu I 4 I 4 } cluster with its neighbouring two [M II (tdas) 2 ] 2– complex anions through their “N” donor atoms from opposite sides. Since the [M II (tdas) 2 ] 2– complex anion generally has a planar geometry, which becomes bent upon supporting a {Cu I 4 I 4 } cluster in the present study, the Cu–S interaction in [M II (tdas) 2 Cu 4 I 4 ] 2– is responsible for the bending conformation of the metal–dithiolato complex unit. This bending structure of the complex anion [M II (tdas) 2 ] 2– in [M II (tdas) 2 Cu 4 I 4 ] 2– describes a situation where the central part of the complex anion is pulled away towards the {Cu I 4 I 4 } cluster through Cu–S bonds. This causes a “curve‐like” structure throughout the resulting doubly‐bridged chain in compounds 1 , 2 and 3 . The second important aspect of the present work is an interesting reactivity of this doubly‐bridged coordination polymer with a bidentate chelating ligand, tetramethylethylenediamine (TMEDA). Compound [Bu 4 N] 2 n [Ni II (tdas) 2 Cu 4 I 4 ] n ( 1 ), a representative member of the series of compounds 1 – 3 , was treated with TMEDA, which resulted in a square planar complex [Ni(tdas)(TMEDA)] ( 4 ) belonging to a mononuclear [M II (N 2 S 2 )]‐type system (where N 2 = bidentate N∩N donor ligand, mostly a bipyridine type, and S 2 = dithiolato ligand) representing an important class of compounds for photophysical properties. Compound 4 exhibits emission at room temperature in the visible region.