Self‐Assembly of Bis(pyrrol‐2‐ylmethyleneamine) Ligands with Cu^II Controlled by Bridging [−(CH₂)_n−] Spacers and Weak Intermolecular C−H···Cu Hydrogen Bonding

Abstract

Bis(pyrrol-2-ylmetyhleneamine) ligands linked by alkyl spacers between the imine nitrogens are shown to give dinuclear dimers or mononuclear monomers, depending on the length of the alkyl linker, upon coordination with Cu II . Ligands containing ethylene or hexylene linkers −(CH 2 ) n − (n = 2, 6) give dinuclear dimers 5 and 8, while propylene and butylene chains (n = 3, 4) give mononuclear monomers 6 and 7. X-ray crystal structural analysis reveals that 5 exists as two very similar isomers 5a and 5b, in which the two ligands are bound to two Cu II centers to form a distorted helical conformation. In the unit cells of 8, two entirely different isomers

Molecular Recognition: Preorganization of a Bis(pyrrole) Schiff Base Derivative for Tight Dimerization by Hydrogen Bonding

“…Metal ions are usually coordinated by 1 as the dianionic conjugate base (structure type 2, where M is a divalent or trivalent metal ion). Examples of crystallographically characterized complexes of type 2 include chelates of Ru II , [2] Pd II , [3] Ni II , [4] Cu II , [5] Mn II , [6,7] Fe II , [7] Sm II , [8] and Co III . [9] Several dinuclear species of the type [M 2 (L) 2 ] are also known for M = Zn II , [10] Mn II , [6] and Cu II [5] where L is a derivative of type 1.…”

Crystal structure of [N,N-bis((pyrrol-2-yl)ethylidene)butane-1,4-diamine-κ4 N,N′,N′′,N′′′]-nickel(II), C16H20N4Ni

“…Schiff base ligands bearing pyrrole units have attracted much recent attention due to their excellent coordination abilities for metal ions [4,5]. The crystal structures of copper(II) and zinc(II) complexes with bis(pyrrol-2-ylmethyleneamine) ligands have been weidely investigated.…”

“…The crystal structures of copper(II) and zinc(II) complexes with bis(pyrrol-2-ylmethyleneamine) ligands have been weidely investigated. By varying the spacers between two pyrrol-2-yl-methyleneamine units, dinuclear dimeric helicates, trinuclear trimeric triangles, and tetranuclear tetrameric square complexes could be generated [4][5][6]. As part of our ongoing studies of pyrrol-2-ylmethyleneaminemetals [6][7][8], the title complex was synthesized and characterized by X-ray diffraction.…”

Structure and optical spectra of bis(pyrrol‐2‐ylmethyleneamine) complexes: A DFT and TDDFT study of the self‐assembly complexes of bis(pyrrol‐2‐ylmethyleneamine) ligands linked by alkyl spacers with Cu(II)

“…Single crystal XRD analyses reveal that by varying the length of the bridge A(CH 2 ) n A spacer between the pyrrol-2-ylmethyeamine units, selfassembly can offer mononuclear monomeric or dinuclear dimeric complex [16]. When n ¼ 2, the self-assembled product is a dinuclear dimeric complex (complex 3), while in the case of n ¼ 3 and 4, the product is mononuclear monomeric complex (complexes 1 and 2), due to the greater flexibility of the spacer between the pyrrol-2-ylmethyleneamine units.…”

“…The samples were synthesized and characterized by time of flight mass spectrometry (TOF-MS), C 13 NMR, and X-ray diffraction (XRD) [16]. The structures of complexes 1-4 were sketched in Figure 1.…”