Heterometallic Copper(II)–Tin(II/IV) Salts, Cocrystals, and Salt Cocrystals: Selectivity and Structural Diversity Depending on Ligand Substitution and the Metal Oxidation State

Abstract

Two copper metallo-ligands [CuL1(H2O)] and [CuL2⊂(H2O)] [H2L1 = N,N′-ethylenebis­(3-methoxysalicylaldimine) and H2L2 = N,N′-ethylenebis­(3-ethoxysalicylaldimine)] have been utilized for the preparation of heterobimetallic eight CuIISnIV complexes [CuL1]2­·[SnMe2Cl4]2–­·(H2ED)2+ (1), [CuL1]2­·[SnEt2Cl4]2–­·(H2ED)2+­·0.5H2O (2), [CuL1]2­·[Sn­(n-Bu)2Cl4]2–­·(H2ED)2+ (3), [CuL1]2­·[SnPh2Cl4]2–­·(H2ED)2+ (4), [CuL1]2­·[SnPh2Cl4]2–­·(H2ED)2+­·2MeOH (5), [CuL2]2­·[SnMe2Cl2(H2O)2]­·0.2H2O (6), [CuL2]­·[Sn­(n-Bu)2­Cl2(H2O)] (7), [CuL2]2­·[SnPh2Cl4]2–­·(H2ED)2+ (8), and two CuIISnII systems [CuL1SnCl]+­·[SnCl3]− (9) and [CuL2SnCl]+­·[SnCl3]− (10) (ED = 1,2-ethylenediamine). Single crystal X-ray structure analyses indicate that 1–5 and 8 are three-component [1×2+1×1+1×1] salt cocrystals of two neutral mononuclear [CuL1]/[CuL2] moieties, one organometallic dianion [SnR2Cl4]2– (R = Me, Et, n-Bu, and Ph), and one doubly protonated 1,2-ethylenediammonium dication H2ED2+, while compounds 6 and 7 are two-component [1×2+1×1]/[1×1+1×1] cocrystals of one/two neutral mononuclear [CuL2] and one neutral organotin­(IV) moieties. Compounds 9 and 10 are two-component salts which are comprised of heterometallic, diphenoxido-bridged, dinuclear CuIISnII cation [CuLSnCl]+ and SnII anionic residue [SnCl3]−. Interestingly, the formation of the salt cocrystals or cocrystals 1–8 and salts 9 and 10 can be well rationalized in terms of several noncovalent weak interactions (O–H···O/N–H···O/N–H···Cl/Cu···Cl/Sn···Cl/Sn···Cu/π···π) which result in the generation of a tetrameric associate in 7, one-dimensional topology in 3–5 and 8–10 and two-dimensional supramolecular associate in 1 and 2. The first metallo-ligand [CuL1(H2O)] produces similar three-component CuII···SnIV···diprotonated diamine salt cocrystals (1–5), attesting to the selectivity toward the formation of this type of compound, while the latter one [CuL2⊂(H2O)] displays a diverse structure forming capability by producing a CuII···SnIV···diprotonated diamine salt cocrystal (8) and two CuII···SnIV cocrystals (6 and 7). Interestingly, no such selectivity is observed for their heterometallic CuIISnII derivatives (9 and 10) which are similar two-component salts and completely different from 1–8. The current study illustrates an excellent example of structural diversity in heterometallic CuIISnII/IV complexes depending on the ligand substitution and metal oxidation state. Moreover, a heterometallic system, such as 1–5 and 8, containing ammonium-stannate adduct (X–NH3·SnX6, X = any) is not known according to the search made on the Cambridge Structural Database (CSD).

Dimeric, Two‐Dimensional and Metal‐Centered Rectangular Heterometallic CuII–AgI/CdII/BaII Systems Derived from a Single Compartmental Ligand

“…As already mentioned, hundreds of heterometallic compounds were reported from single‐ or double‐compartmental acyclic Schiff base ligands (the types of single‐compartmental and double‐compartmental ligands have already been mentioned). Most of these compounds are of the following types: (i) Dinuclear;‐,,,‐,‐ (ii) Trinuclear;‐,‐,,,‐,, (iii) Dinuclear based clusters or polymers;,,,,,,,,,‐,, (iv) Trinuclear based clusters or polymers;,,,,, (v) Cocrystals of dinuclear or trinuclear units and mononuclear units ,,,,. In some rare cases, tetrametallic MCu II 3 ‘Stars’ (M=Cd II , Zn II , Cu II , Ni II , Mn II , Na I ) which are metal‐centered triangles or ‘Stars’, have been stabilized ,,,.…”

“…As already mentioned, hundreds of heterometallic compounds were reported from single-or doublecompartmental acyclic Schiff base ligands (the types of single- compartmental and double-compartmental ligands have already been mentioned). Most of these compounds are of the following types: (i) Dinuclear; [1][2][3][4][5][6][7][8][9]11,19,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][47][48][49][50] (ii) Trinuclear; [10][11][12][13][14][15][20][21][22]25,26,[37][38][39][40]50,51] (iii) Dinuclear based clusters or polymers; [6,10,11,…”

“…Hundreds of heteronuclear compounds were prepared following this methodology. Those heteronuclear compounds include dinuclear,‐,,,‐,‐ trinuclear,‐,‐,,,‐,,, tetranuclear (including metal‐centered triangles (‘stars’) systems),,,,,,,,,,,,, cocrystals,,,, and coordination polymers ,,,,,,,,,,…”

Fluorine‐Substituted Ligands Induce Structural Diversity of Coordination Compounds

“…To explain more, Hazra et al examine structural dependence on simultaneous changes in both ligand substitution and metal oxidation state. Indeed they employ HL OMe and HL OEt ligands, where L OR is N,N′‐ethylenebis(3‐Alkoxysalicylaldimine), in heterometallic copper(II)−tin(II/IV) systems and compare final eight complexes . Furthermore, Du and co‐worker prepare a series of complexes from CdCl 2 and 5‐fluoro/chloronicotinic acid ligands in different solvents and study substitution changes together with solvent effect .…”

Crystal structure of bis{μ-2-methoxy-6-[(methylimino)methyl]phenolato}bis({2-methoxy-6-[(methylimino)methyl]phenolato}nickel(II)) involving different coordination modes of the same Schiff base ligand

“…In the present work, the title compound was isolated in an attempt to prepare a heterometallic Ni/Sn complex with HL in the reaction of nickel powder and SnCl 2 Á2H 2 O, with the Schiff base formed in situ in a methanol/ DMF mixture in a 1:1:2 molar ratio. Similarly to the synthesis of CoL 3 ÁDMF (Nesterova et al, 2018), HL does not enable the formation of a heterometallic Sn-containing species, in contrast to its compartmental analogues 3-R-salicylaldehyde-ethylenediamine (R = methoxy-, ethoxy-), HL 0 , that afford heterometallic, diphenoxido-bridged, dinuclear Cu II Sn II cations [CuL 0 SnCl] + (Hazra et al, 2016).…”