Assembly of Lipophilic Tetranuclear (Cu₄ and Zn₄) Molecular Metallophosphonates from 2,4,6-Triisopropylphenylphosponic Acid and Pyrazole Ligands

Abstract

A sterically hindered aryl phosphonic acid ArP(O)(OH)2 (2) (Ar = 2,4,6-isopropylphenyl) was synthesized and structurally characterized. ArP(O)(OH)2 forms an interesting hydrogen-bonded corrugated sheet-type supramolecular structure in the solid-state. A three-component reaction involving ArP(O)(OH)2, 3,5-dimethylpyrazole(DMPZH), and Cu(CH3COO)2.H2O produces the tetranuclear Cu(II) compound [Cu4(mu3-OH)2{ArPO2(OH)}2(CH3CO2)2(DMPZH)4][CH3COO]2.CH2Cl2 (3). A similar three-component reaction involving ArP(O)(OH)2, 3,5-dimethylpyrazole, and Zn(CH3COO)2.2H2O yields the tetranuclear Zn(II) compound [Zn4{ArPO3}2{ArPO2(OH)}2{DMPZH}4(DMPZ)2].5MeOH (4). While 3 has been found to have an asymmetric cage structure where two dinuclear copper cores are bridged by bidentate [ArPO2(OH)]- ligands, 4 possesses an open-book tricyclic structure composed of three fused metallophosphonate rings. Magnetic studies on 3 revealed antiferromagnetic behavior.

Molecular Metal Phosphonates

“…All of the rings are puckered, and the relationship of the two terminal rings vis-a-vis the central ring is trans (Figure 57a). 36 Similar types of structural forms are also known in the 194 On the other hand, another tetranuclear complex, [Mn 4 (C 5 H 9 PO 3 ) 2 (phen) 8 (H 2 O) 2 ]·(ClO 4 ) 4 , possesses a central dinuclear motif containing an eight-membered Mn 2 P 2 O 4 ring (Figure 57b). 36 In this structure, the bridging phosphonate ligands are present in the central region.…”

2,6-(Diphenylmethyl)-Aryl-Substituted Neutral and Anionic Phosphates: Approaches to H-Bonded Dimeric Molecular Structures

“…The shortest distance is 1.478(2) Å, corresponding to the formal P=O present in this compound. This is larger when compared with that of the P=O distance in 2,4,6‐ i Pr 3 C 6 H 2 POCl 2 (1.461(9) Å) . The slight lengthening of this P=O bond in 9 CH3COCH3 is the result of the hydrogen‐bonding which involves this bond ( vide infra ).…”

“…For example, tert ‐butylphosphonic acid forms two different types of aggregates in the solid state: a H‐bonded polymer is obtained upon crystallization from THF while a hexamer is observed in the crystals obtained from CDCl 3 . Other types of structures of organophosphonic acids range from discrete assemblies to polymeric chains and sheets ,…”

P–C Bond Cleavage-Assisted Lanthanide Phosphate Coordination Polymers

“…[32][33][34] We have a long-standing interest in the use of phosphonate ligands for the preparation of polynuclear molecular assemblies whose nuclearity can be tuned over a wide range by the use of synthetic methods that include variation of the steric bulk on the phosphonate ligand and/or the use of an ancillary nitrogen ligand. [35][36][37][38][39][40][41][42][43][44] More recently we have started to engage in the chemistry of polynuclear lanthanide complexes from a molecular magnetism standpoint. [45][46][47] Single-crystal X-ray structural studies reveal that compounds 1-3 crystallize in the monoclinic crystal system (C2/c (1 and 2), P2 1 /n (3)).…”