Substitution and derivatization reactions of a water soluble iron(II) complex containing a self-assembled tetradentate phosphine ligand

Facile substitution reactions of the two water ligands in the hydrophilic tetradentate phosphine complex cis-[Fe{(HOCH2)P{CH2N(CH2P(CH2OH)(2))CH2}(2)P(CH2OH)}(H2O)(2)](SO4) ( abbreviated to [Fe(L-1)(H2O)(2)](SO4),1) take place upon addition of Cl-, NCS-, N-3(-), CO32- and CO to give [Fe(L-1)X-2] (2, X = Cl; 4, X = NCS; 5, X= N-3), [Fe(L-1)(kappa(2)-O2CO)], 6 and [Fe(L-1)(CO)(2)](SO4), 7. The unsymmetrical mono-substituted intermediates [Fe(L-1)(H2O)(CO)](SO4) and [Fe(L-1)(CO)(kappa(1)-OSO3)] (8/9) have been identified spectroscopically en-route to 7. Treatment of 1 with acetic anhydride affords the acylated derivative [Fe{(AcOCH2)P{CH2N(CH2P(CH2OAc)(2))CH2}(2)P(CH2OAc)}(kappa(2)-O2SO2)] (abbreviated to [Fe(L-2)(kappa(2)-O2SO2)], 10), which has increased solubility over 1 in both organic solvents and water. Treatment of 1 with glycine does not lead to functionalisation of L-1, but substitution of the aqua ligands occurs to form [Fe(L-1)(NH2CH2CO2-kappa N-2, O)](HSO4), 11. Compound 10 reacts with chloride to form [Fe(L-2)Cl-2] 12, and 12 reacts with CO in the presence of NaBPh4 to form [Fe(L-2)Cl(CO)](BPh4) 13b. Both of the chlorides in 12 are substituted on reaction with NCS- and N3- to form [ Fe( L2)( NCS) 2] 14 and [ Fe( L2)( N3) 2] 15, respectively. Complexes 2 (.) H2O, 4(.)2H(2)O, 5(.)0.812H(2)O, 6(.)1.7H(2)O, 7 (.) H2O, 10(.)1.3CH(3)C(O)CH3, 12 and 15(.)0.5H(2)O have all been crystallographically characterised.