Polyoxometalate‐Based Lanthanide Complexes: Insights into the Design and Structural Control Based on Multivariate Analysis

Two novel lanthanide‐based complexes, [NBu 4 ] 3 [YbH(PW 11 O 39 )(phen) 2 ]·H 2 O ( LM 4 –UBO–1–Yb ) and K 13 [Dy(SiW 11 O 39 ) 2 ]·21H 2 O ( LM 4 –UBO–2–Dy ), are synthesized and characterized to explore how Keggin monolacunary polyoxometalates (KMLPOMs) affect Ln III geometry. SHAPE analysis shows both complexes adopt square antiprismatic (SAPR) geometries with pseudo‐D4d symmetry. LM 4 –UBO–1–Yb has a slightly distorted SAPR geometry, with a displacement parameter ( D ) of 1.068 Å, influenced by organic ligands, while LM 4 –UBO–2–Dy is more rigid ( D = 1.298 Å). A structural multivariate analysis of 185 KMLPOM‐based Ln III complexes identifies four main types: mononuclear inorganic, mononuclear hybrid, dinuclear hybrid, and dinuclear inorganic. Structural trends reveal that [BW 11 O 39 ] 9− and [PW 11 O 39 ] 7− prefer SAPR geometries, while [GeW 11 O 39 ] 8− and [SiW 11 O 39 ] 8− favor bicapped trigonal prism (BTPR) geometries. D values below ≈1.10 Å are linked to BTPR geometries, while higher values align with SAPR geometries. This study highlights the heteroatom's ionic radius as a key factor in determining geometry and offers predictive guidelines for designing Ln III ‐KMLPOM systems.