Self-Assembly of Tert-Butyl-Substituted Pentaphosphaferrocenes with Copper Halides: Selective Formation of One- and...

Over the past three decades, pentaphosphaferrocene [Cp*Fe(η⁵-P₅)] (1*) has emerged as a versatile building block in coordination chemistry, enabling the construction of a wide range of nanosized spherical aggregates and extended coordination polymers (CPs). Previous studies have shown that modification of substituents in fully substituted cyclopentadienyl ligands strongly influences the size of the resulting spherical aggregates. However, the impact of partially substituted cyclopentadienyl ligands remains unexplored. Herein, we investigate the reactivity of the cyclo-P₅ ligands in tert-butyl-substituted pentaphosphaferrocenes [Cp^RFe(η⁵-P₅)] {Cp^R = Cp″: η⁵-1,3-(^tBu)₂C₅H₃ (1″) and Cp‴: η⁵-1,2,4-(^tBu)₂C₅H₂ (1‴)} towards Cu(I) halides (CuX; X = Cl, Br and I). These reactions yield a series of CPs (2-9) that are structurally characterized by single-crystal X-ray diffraction, multinuclear NMR spectroscopy, and ESI-MS spectrometry. Reactions of 1″ with CuCl and CuBr afford one-dimensional CPs while reactions with CuI show a pronounced dependence on stoichiometry, leading to CPs with different structural topologies and dimensionalities. In contrast, the bulkier derivative 1‴ consistently forms two-dimensional networks. These include a regular sheet-like framework (7), an architecture composed of alternating mesh sizes (8), and a distinctive double-layered structure (9) featuring Cu₄I₃ and Cu₄I₄ nodes interconnected by organometallic (1‴) and inorganic (CuI₂) linkers. Solution studies indicate partial depolymerization of the polymers, consistent with the lability of Cu-P interactions.