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. 2022 Nov 9;27(22):7704.
doi: 10.3390/molecules27227704.

Synthesis and Characterisation of Novel Bis(diphenylphosphane oxide)methanidoytterbium(III) Complexes

Shalini Rangarajan  1 , Owen A Beaumont  2 , Maravanji S Balakrishna  1 , Glen B Deacon  2 , Victoria L Blair  2
Affiliations

Synthesis and Characterisation of Novel Bis(diphenylphosphane oxide)methanidoytterbium(III) Complexes

Shalini Rangarajan et al. Molecules. .

Abstract

Reaction of [YbCp2(dme)] (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (H2dppmO2) leads to deprotonation of the ligand H2dppmO2 and oxidation of ytterbium, forming an extremely air-sensitive product, [YbIII(HdppmO2)3] (1), a six-coordinate complex with three chelating (OPCHPO) HdppmO2 ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(C6F5)2, and H2dppmO2. In a further preparation, the reaction of [Yb(C6F5)2] with H2dppmO2, not only yielded compound 1, but also gave a remarkable tetranuclear cage, [Yb4(µ-HdppmO2)6(µ-F)6] (2) containing two [Yb(µ-F)]2 rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmO2 donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-H2C6F4 and m-H2C6F4, the last being an unexpected product.

Keywords: C-F activation; fluoride cage; methanide; phosphine oxide; ytterbium.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Previous studies (reaction 1a [14]) and our current work (1b and 1c) on rare earth complexes from reactions of H2dppmO2.
Scheme 2
Scheme 2
Rational synthesis of [Yb(HdppmO2)3] 1.
Figure 1
Figure 1
The infrared spectrum of complex [Yb(HdppmO2)3] 1 (top) and free ligand H2dppmO2 (below) in Nujol mull.
Figure 2
Figure 2
The molecular structure of [Yb(HdppmO2)3) 1. All hydrogen atoms are omitted for clarity except backbone methanide protons. Lattice acetonitrile is omitted for clarity. Displacement ellipsoids are drawn at the 30% probability level. Selected bond lengths (Å) and bond angles (°) can be found in Table S4.
Figure 3
Figure 3
Variable temperature (VT) 1H NMR spectrum of complex 1 showing aromatic region only, at 25, −15 and −55 °C in CD2Cl2. Full 1H NMR spectra can be found in Figure S7a.
Figure 4
Figure 4
Arrangement of phenyl groups on P atoms within the metallacycle of complex.
Figure 5
Figure 5
Boat and twist-boat conformers of the metallacycles in complex 1.
Scheme 3
Scheme 3
One pot RTP synthesis of complex 1.
Scheme 4
Scheme 4
Protolysis reaction for the formation of 1 and [Yb4(µ—HdppmO2)6(µ—F)6] 2.
Figure 6
Figure 6
The molecular structure of [Yb4(µ-HdppmO2)6(µ-F)6] 2. All hydrogen atoms are omitted for clarity except backbone methanide protons. Displacement ellipsoids are drawn at the 30% probability level. The lattice solvents THF and C6D6 have been omitted and phenyl groups drawn in wire frame for better clarity. Symmetry operator = 1 − x,+y,1/2 − z. Selected bond lengths (Å) and bond angles (°) can be found in Table S4.
Scheme 5
Scheme 5
Proposed mechanism for C-F activation and formation of complex 2.
See this image and copyright information in PMC

References

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