Four coordination clusters using fluorenyl and carbazyl phosphonates as ligands

Abstract

Four polynuclear complexes, [Co₄(FluPO₃)₂(FluPO₃H)₂(CH₃CO₂)₂(py)₆(H₂O)₂] (1), [Mn₅O₃(FluPO₃)₂(PhCO₂)₅(CH₃OH)(phen)₂] (2), [Mn₅O₃(CarbPO₃)₂(PhCO₂)₅(CH₃OH)(phen)₂] (3) and [Mn^II₄Mn^III₆O₂(OH)₂(CarbPO₃)₈(PhCO₂)₄(py)₆] (4) (FluPO₃H₂ = (9-methyl-9H-fluoren-9-yl)phosphonic acid, CarbPO₃H₂ = N-carbazolylmethylphosphonic acid), were synthesized and characterized. In compound 1, the cobalt centers are bridged by phosphonate ligands into a circle. Both the cores of complexes 2 and 3 feature three μ₃-O and two capping FluPO₃²⁻ or CarbPO₃²⁻ groups bridging five Mn^III atoms to form a basket-like cage structure. Complex 4 contains divalent and trivalent ions and has a butterfly-like [Mn^II₄Mn^III₆O₂(OH)₂(CarbPO₃)₄]¹²⁺ core with four phosphonate ligands in the body position and five Mn atoms on each wing side. Magnetic susceptibility measurements reveal the existence of antiferromagnetic interactions in 1, 2·4CH₃CN·2H₂O, 3·PhCO₂H·6CH₃CN·2H₂O and 4·py·8H₂O. Fitting the experimental data led to the following parameters: J₁ = −10.1 cm⁻¹, J₂ = −18.0 cm⁻¹, J₃ = −8.0 cm⁻¹, J₄ = −5.9 cm⁻¹, J₅ = −2.8 cm⁻¹, g = 2.0 for 2·4CH₃CN·2H₂O, and J₁ = −7.4 cm⁻¹, J₂ = −22.8 cm⁻¹, J₃ = −6.9 cm⁻¹, J₄ = −4.8 cm⁻¹, J₅ = −0.3 cm⁻¹, g = 2.0 for 3·PhCO₂H·6CH₃CN·2H₂O.