SYNTHESIS OF MOLECULAR PHOSPHONATES IN APROTIC SOLVENTS
Libor Tanzinger,a
Zdeněk Moraveca
and Jiří Pinkasa
a
Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, Brno
CZ-61137, Czech Republic E-mail address: tanzingerlibor@gmail.com
The transition metals complexes with the organophosphonate ligands of the general
formula [RPO3]2are
much less studied compared to the carboxyl and similar
compounds.1
This is partly due to their coordination capabilities that allow the
formation of multidentate insoluble complexes. Indeed, there are a large number of
compounds with a multidimensional structure, such as coordination polymers (1D),
layered structures (2D) and columnar or tubular (3D), however soluble molecular
phosphonates (0D) are less known. The third group of periodic table is one of the less
explored groups of elements. Although their well characterized phosphonic compounds
have been prepared, they are not numerous.2
Therefore, a series of experiments was
conducted with selected phosphonic acids and their silylated esters with anhydrous
transition metal chlorides in an aprotic solvent environment such as THF and pyridine.
The obtained products were studied by multinuclear NMR spectroscopy and in cases of
successful crystal isolation by SCXRD. From the the reactions of tert-butyl phosphonic
acid with yttrium(III) and lanthanum(III) it is [μ3-t
BuP(O)3]4(YClpy2)2(YCl2pyH)2 in
pseudo-cubane geometry with [Hpy]3[YCl6]·2py as a byproduct and La4[μ6-
t
BuP(O)3]2[μ4-t
BuPO2(OH)]2(μ2-Cl)2Cl8(Hpy)6 with bridged-square geometry.3,4
Reactions of other transition metals were studied as well. Reaction of anhydrous CuCl2
with PhPO3H2 and KOt
Bu in dry pyridine yieded two products. A product with formula
[Cu6(μ3-PhPO3)4(μ4-PO4)·12py]Cl with adamantane-like structure and (Cupy)6(μ3PhPO3)4(μ4-PhPO3)2
with cluster geometry. Reaction of salicylphosphonic acid
(salPO3H2) with CuCl2 and KOt
Bu in dry pyridine produced 1D product
[Cupy4(salPOH2)2]n.
References
1. Chandrasekhar, V.; Senapati, T.; Dey, A.; Hossain, S. Dalt. Trans. 2011, 40 (20),
5394-5418.
2. Goura, J.; Chandrasekhar, V. Chem. Rev. 2015, 115 (14), 6854–6965.
3. Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.; Puschmann, H. J.
Appl. Crystallogr. 2009, 42 (2), 339–341.
4. Marvin was used for drawing, displaying and characterizing chemical structures,
substructures and reactions, Marvin 17.4.3 2017, ChemAxon
(https://www.chemaxon.com)