Cobalt is an essential metal ion involved in key biomolecules, re
gulatin
g processes in human physiolo
gy. As ametal ion, Co(II) assumes forms, which are dictated by the nature of or
ganic binders in biolo
gical fluids, and theconditions under which metal ion li
gand interactions arise. Amon
g the various low molecular mass metal ion bindersin biolo
gical fluids are amino acids, or
ganic acids, as well as their variably phosphorylated forms. As a representativemetal ion binder, the or
ganophosphonate li
gand H
2O
3P-CH
2-NH
2+-CH
2-PO
3H
- was employed in aqueous reactionswith Co(II), ultimately leadin
g to the isolation of complex [Co(C
2H
8O
6NP
2)
2(H
2O)
2] (
1) at pH 2. The complex wascharacterized analytically, spectroscopically (FTIR, UV-vis, EPR), and ma
gnetically. Compound
1 crystallizes inthe monoclinic space
group
P2
1/
n, with
a = 7.361(3) &Arin
g;,
b = 8.133(3) &Arin
g;,
c = 14.078(5) &Arin
g;,
ges/
gifchars/beta2.
gif" BORDER=0 ALIGN="middle"> = 104.40(1)
ges/entities/de
g.
gif">,
V =816.3(5) &Arin
g;
3, and
Z = 2. X-ray crystallo
graphy reveals that
1 is a compound with a molecular type of lattice. In it,there exist mononuclear octahedral sites of Co(II) surrounded by oxy
gens, belon
gin
g to terminal phosphonates andbound water molecules. Both ends of the li
gand zwitterionic form are involved in bindin
g to adjacent Co(II) ions,thus creatin
g tetranuclear 32-membered rin
gs, with cavities extendin
g in two dimensions and holes in the thirddimension throu
ghout the lattice of
1. Similar structural features were observed in other metal or
ganophosphonatelattices of potential catalytic and chemical reactivity. The ma
gnetic and EPR data on
1 support the presence of ahi
gh-spin octahedral Co(II) in an oxy
gen environment, havin
g a
ground state with an effective spin
S =
1/
2. Thesolution UV-vis and EPR data su
ggest retention of the hi
gh-spin octahedral Co(II) ion, consistent with thema
gnetization measurements on
1. Collectively, the data reflect the existence of a soluble Co(II)-iminodiphosphonatespecies not unlike those expected in biolo
gical fluids containin
g the specific li
gand or li
gands similar to that. Bothbiolo
gically relevant perspectives and a synthetic outlook into Co(II)-or
ganophosphonate materials are discussed.