Architecture Dependence on the Steric Constrains of the Ligand in Cyano-Bridged Copper(I) and Copper(II)−Copper(I) Mixed-Valence Polymer Compounds Containing Diamines:  Crystal Structures and Spectroscopic and Magnetic Properties

Abstract

A family of cyano-bridged copper(II)-copper(I) mixed-valence polymers containing diamine ligands of formula [Cu(pn)(2)][Cu(2)(CN)(4)] (1, pn = 1,2-propanediamine), [Cu(2)(CN)(3)(dmen)] (2, dmen = N,N-dimethylethylenediamine), and [Cu(3)(CN)(4)(tmen)] (3, tmen = N,N,N',N'-tetramethylethylenediamine) have been prepared with the aim of analyzing how their architecture may be affected by steric constraints imposed by the diamine ligands. In the absence of diamine and with use of the voluminous NEt(4)(+) cation, the copper(I) polymer [NEt(4)][Cu(2)(CN)(3)] (4) forms. The structure of 1 consists of a three-dimensional diamond-related anionic framework host, [Cu(2)(CN)(4)](2-), and enclathrated [Cu(pn)(2)](2+) cations. The structure of 2 is made of neutral corrugated sheets constructed from fused 18-member nonplanar rings, which contain three equivalent copper(I) and three equivalent copper(II) centers bridged by cyanide groups in an alternative form. The 3D structure of 3 consists of interconnected stair-like double chains built from fused 18-member rings, which adopt a chairlike conformation. Each ring is constructed from two distorted trigonal planar Cu(I) centers, two bent seemingly two-coordinated Cu(I) centers, and two pentacoordinated Cu(II) atoms. The structure 4 is made of planar anionic layers [Cu(2)(CN)(3)](n)(n-) lying on mirror planes and NEt(4)(+) cations intercalated between the anionic layers. From the X-ray structural results and calculations based upon DFT theory some conclusions are drawn on the structure-steric factors correlation in these compounds. Compound 1 exhibits very weak luminescence at 77 K with a maximum in the emission spectrum at 520 nm, whereas compound 4 shows an intense luminescence at room temperature with a maximum in the emission spectrum at 371 nm. Polymers 2 and 3 exhibit weak antiferromagnetic magnetic exchange interactions with J = -0.065(3) and -2.739(5) cm(-1), respectively. This behavior have been justified on the basis of the sum of two contributions: one arising from the pure ground-state configuration and the other one from the charge-transfer configuration Cu(I)-CN-Cu(II)-CN-Cu(II) that mixes with the ground-state configuration.

Synthesis and Crystal Structures of Four Cyanide‐Bridged Coordination Polymers

“…As the reaction was carried out under hydrothermal conditions, it is not surprising that the Cu II and Fe III ions have been reduced to Cu I and Fe II ions by cyanide or N-heterocyclic ligands, such as 1,10-phen or pyridine derivatives. [17][18][19] The cyanide in 1 is provided by the ferricyanide anions. A view of the metal coordination environment is presented in Figure 1.…”

Total Spontaneous Resolution of Chiral Covalent Networks from Stereochemically Labile Metal Complexes

“…Several polymeric mixed-valence copper(i/ii) compounds crystallise with one-dimensional, [18][19][20] two-dimensional [21][22][23][24] and three-dimensional arrays, [21][22][23][24][25][26][27] but there seem to be few examples of interpenetration [24,25] and few in which the network is built up primarily from covalent bonds [21,[24][25][26] rather than weak interactions. Even examples of covalent interpenetrating (10,3)-a networks with other transition metals appear to be somewhat scarce.…”

Crystal structure of (acetonitrile-N)copper(I) cyanide, [Cu(CH3CN)][CN]

“…A part of a single layer of the two-dimensional network is shown in the top of the figure, the interlocking of this layers by the acetonitrile molecules at the bottom. Plane [3,4] and undulated layers [5,6] of (CuCN) 6 rings or (CuCN) 8 rings [7] are already known. Layers built of (CuCN)4 rings are less common [8].…”