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

Two novel lanthanide-based complexes, [NBu<inf>4</inf>]<inf>3</inf>[YbH(PW<inf>11</inf>O<inf>39</inf>)(phen)<inf>2</inf>]·H<inf>2</inf>O (LM4–UBO–1–Yb) and K<inf>13</inf>[Dy(SiW<inf>11</inf>O<inf>39</inf>)<inf>2</inf>]·21H<inf>2</inf>O (LM4–UBO–2–Dy), are synthesized and characterized to explore how Keggin monolacunary polyoxometalates (KMLPOMs) affect LnIII geometry. SHAPE analysis shows both complexes adopt square antiprismatic (SAPR) geometries with pseudo-D4d symmetry. LM4–UBO–1–Yb has a slightly distorted SAPR geometry, with a displacement parameter (D) of 1.068 Å, influenced by organic ligands, while LM4–UBO–2–Dy is more rigid (D = 1.298 Å). A structural multivariate analysis of 185 KMLPOM-based LnIII complexes identifies four main types: mononuclear inorganic, mononuclear hybrid, dinuclear hybrid, and dinuclear inorganic. Structural trends reveal that [BW<inf>11</inf>O<inf>39</inf>]9− and [PW<inf>11</inf>O<inf>39</inf>]7− prefer SAPR geometries, while [GeW<inf>11</inf>O<inf>39</inf>]8− and [SiW<inf>11</inf>O<inf>39</inf>]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 LnIII-KMLPOM systems. © 2025 Wiley-VCH GmbH.