High-nuclearity cerium oxide clusters do exist: condensation reactions starting from cerium coordination polymers result in ligand-terminated {Ce ^III/IV ₁₀ } and {Ce ^III/IV ₂₂ } oxide clusters, which exhibit formation and structural aspects that are partly similar and partly contrary to classical polyoxometalate chemistry.

A family of wheel-shaped charge-neutral heterometallic {Fe^III₄Ln^III₂}- and {Fe^III₁₈M^III₆}-type coordination clusters demonstrates the intricate interplay of solvent effects and structure-directing roles of semiflexible bridging ligands. The {Fe₄Ln₂}-type compounds [Fe₄Ln₂(O₂CCMe₃)₆(N₃)₄(Htea)₄]·2(EtOH), Ln = Dy (1a), Er (1b), Ho (1c); [Fe₄Tb₂(O₂CCMe₃)₆(N₃)₄(Htea)₄] (1d); [Fe₄Ln₂(O₂CCMe₃)₆(N₃)₄(Htea)₄]·2(CH₂Cl₂), Ln = Dy (2a), Er (2b); [Fe₄Ln₂(O₂CCMe₃)₄(N₃)₆(Htea)₄]·2(EtOH)·2(CH₂Cl₂), Ln = Dy (3a), Er (3b) and the {Fe₁₈M₆}-type compounds [Fe₁₈M₆(O₂CCHMe₂)₁₂(Htea)₁₈(tea)₆(N₃)₆]·n(solvent), M = Dy (4, 4a), Gd (5), Tb (6), Ho (7), Sm (8), Eu (9), and Y (10) form in ca. 20–40% yields in direct reaction of trinuclear Fe^III pivalate or isobutyrate clusters, lanthanide/yttrium nitrates, and bridging triethanolamine (H₃tea) and azide ligands in different solvents: EtOH for the smaller {Fe₄Ln₂} wheels and MeOH/MeCN or MeOH/EtOH for the larger {Fe₁₈M₆} wheels. Single-crystal X-ray diffraction analyses revealed that 1–3 consist of planar centrosymmetric hexanuclear clusters built from Fe^III and Ln^III ions linked by an array of bridging carboxylate, azide, and aminopolyalcoholato-based ligands into a cyclic structure with a cavity, and with distinct sets of crystal solvents (2 EtOH per formula unit in 1a–c, 2 CH₂Cl₂ in 2, and 2 EtOH and 2 CH₂Cl₂ in 3). In 4–10, the largest 3d/4f wheels currently known, nearly linear Fe₃ fragments are joined via mononuclear Ln/Y units by a set of isobutyrates and amino alcohol ligands into virtually planar rings. The magnetic properties of 1–10 reveal slow magnetization relaxation for {Fe₄Tb₂} (1d) and slow relaxation for {Fe₄Ho₂} (1c), {Fe₁₈Dy₆} (4), and {Fe₁₈Tb₆} (6).

A series of cyanide-bridged coordination networks has been prepared which contain [Ru(phen)(CN)₄]²⁻ anions, Ln(III) cations, and additional oligopyridine ligands (1,10-phenanthroline, 2,2′:6′,2‴-terpyridine or 2,2′-bipyrimidine) which coordinate to the Ln(III) centres. Five structural types have been identified and examples of each type of structure are described: these are hexanuclear Ru₄Ln₂ clusters; two-dimensional Ru–Ln sheets with a honeycomb pattern of edge-linked Ru₆Ln₆ hexagons; one-dimensional chains consisting of two parallel cross-linked strands in a ladder-like arrangement; simple single-stranded chains of alternating Ru/Ln components; and a one-dimensional ‘chain of squares’ in which Ru₂Ln₂ squares are linked by bipyrimidine bridging ligands which connect to the Ln(III) corners of adjacent squares in the sequence. The ³MLCT luminescence characteristic of the [Ru(phen)(CN)₄]²⁻ units is quenched in those networks containing Ln(III) which have low-lying near-infrared luminescent f–f states [Pr(III), Nd(III), Er(III), Yb(III)], with sensitised Ln(III)-based near-IR luminescence generated by d → f energy-transfer. The rate of d → f energy-transfer, and hence the degree of quenching of the ³MLCT luminescence from the [Ru(phen)(CN)₄]²⁻ units, depends on the availability of f–f levels of an appropriate energy on the Ln(III) centre, with Nd(III) (with a high density of low-lying f–f states) being the most effective energy-acceptor and Yb(III) (with a single low-lying f–f state) being the least effective. Rates of d → f energy-transfer to different Ln(III) centres could be determined from both the residual (partially quenched) lifetimes of the ³MLCT luminescence, and—in the case of the Yb(III) networks—by a rise-time for the sensitised near-IR luminescence. The presence of the ‘blocking’ polypyridyl ligands, which reduced the number of cyanide and water ligands that would otherwise coordinate to the Ln(III) centres, resulted in increases in the Ln(III)-based emission lifetimes compared to networks where these blocking ligands were not used.