Isolation and Electronic Structures of Lanthanide(II) Bis(trimethylsilyl)phosphide Complexes
While lanthanide (Ln) silylamide chemistry is mature, the corresponding silylphosphide chemistry is underdeveloped, with [Sm{P(SiMe<sub>3</sub>)<sub>2</sub>}{μ-P(SiMe<sub>3</sub>)<sub>2</sub>}<sub>3</sub>Sm(THF)<sub>3</sub>] being the sole example of a structurally authenticated Ln(II) silylphosphide complex. Here, we expand the Ln(II) {P(SiMe<sub>3</sub>)<sub>2</sub>} chemistry through the synthesis and characterization of nine complexes. The dinuclear "ate" salt-occluded complexes [{Ln[P(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>(THF)}<sub>2</sub>(μ-I)K<sub>3</sub>(THF)] (<b>1-Ln</b>; Ln = Sm, Eu) and polymeric "ate" complex [KYb{P(SiMe<sub>3</sub>)<sub>2</sub>}<sub>3</sub>{μ-K[P(SiMe<sub>3</sub>)<sub>2</sub>]}<sub>2</sub>]<sub>∞</sub> (<b>2-Yb</b>) were prepared by the respective salt metathesis reactions of parent [LnI<sub>2</sub>(THF)<sub>2</sub>] (Ln = Sm, Eu, Yb) with 2 or 3 equiv of K{P(SiMe<sub>3</sub>)<sub>2</sub>} in diethyl ether. The separate treatment of these complexes with either pyridine or 18-crown-6 led to the formation of the mononuclear solvated adducts <i>trans</i>-[Ln{P(SiMe<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(py)<sub>4</sub>] (<b>3-Ln</b>; Ln = Sm, Eu, Yb) and [Ln{P(SiMe<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(18-crown-6)] (<b>4-Ln</b>; Ln = Sm, Eu, Yb), with concomitant loss of K{P(SiMe<sub>3</sub>)<sub>2</sub>}. The complexes were characterized by a combination of NMR, electron paramagnetic resonance (EPR), attenuated total reflectance infrared (ATR-IR), electronic absorption and emission spectroscopies, elemental analysis, SQUID magnetometry, and single crystal X-ray diffraction. We find that these complexes contrast with those of related Ln(II) bis(silyl)amide complexes due to differences in ligand donor atom hardness and ligand steric requirements from Ln-P bonds being longer than Ln-N bonds. This leads to higher coordination numbers, shorter luminescence lifetimes, and smaller eas<i>y</i>-axis magnetic anisotropy parameters.
Authors
- George F. S. Whitehead (ORCID: https://orcid.org/0000-0003-1949-4250)
- Meagan S. Oakley (ORCID: https://orcid.org/0000-0001-5072-7572)
- David Paul Mills (ORCID: https://orcid.org/0000-0003-1575-7754)
- Louise S. Natrajan (ORCID: https://orcid.org/0000-0002-9451-3557)
- Eric J. L. McInnes (ORCID: https://orcid.org/0000-0002-4090-7040)
- Adam Brookfield (ORCID: https://orcid.org/0000-0001-5864-0041)
- Jack E. Baldwin (ORCID: https://orcid.org/0000-0001-8612-0174)
Institutions
- University of Manchester (GB)
Publication Details
- Journal
- Inorganic Chemistry
- Published
- 2024-09-16
- DOI
- https://doi.org/10.1021/acs.inorgchem.4c02888
- Citations
- 9
- Primary Topic
- Organometallic Complex Synthesis and Catalysis
- Type
- article
- Field-Weighted Citation Impact
- 2.25
Funders
- University of Manchester
- Engineering and Physical Sciences Research Council
- H2020 European Research Council