Abstract:The first examples of tinbridged [1]ferrocenophanes, Fe(h-C 5 H 4 ) 2 -SntBu 2 (7a) and Fe(h-C 5 H 4 ) 2 SnMes 2 (7b) have been synthesized by the low-temperature reaction of Fe(h-C 5 H 4 Li) 2´n TME-DA (TMEDA N,N,N',N'-tetramethylethylenediamine) with tBu 2 SnCl 2 and Mes 2 SnCl 2 (Mes 2,4,6-trimethylphenyl), respectively. They were isolated in 65 % (7a) and 85% (7b) yield as orange crystalline solids, which were characterized by multinuclear NMR and UV/Vis spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction. The tilt angles between the planes of the cyclopentadienyl rings are 14.1(2)8 for 7a and 15.2(2)8 (average) for the three independent molecules of 7b in the unit cell. Although they have significantly smaller tilt angles than analogous [1]ferrocenophanes with the lighter Group 14 elements silicon or germanium in the bridge, 7 a and 7 b still readily undergo ring-opening polymerization (ROP) by thermal reaction in the solid state (7 a at 150 8C; 7 b at 180 8C), to give highmolecular-weight poly(ferrocenylstannane)s [Fe(h-C 5 H 4 ) 2 SntBu 2 ] n (8 a) and [Fe(h-C 5 H 4 ) 2 SnMes 2 ] n (8 b). Remarkably, 7 a and 7 b were also found to polymerize in solution at room temperature in the absence of externally added initiators. ROP is much more rapid for 7 a than for 7 b in solution. The cyclic dimers [Fe(h-C 5 H 4 ) 2 SnR 2 ] 2 (3; R tBu, Mes) were formed as by-products in amounts which depended on the solvent. Electrochemical studies of the cyclic dimers and polymers indicated the presence of significant Fe´´´Fe interactions that are mediated by the tin-atom spacer. When benzene solutions of 7 a and 7 b were treated with small amounts of Karstedts catalyst, slower polymerization was observed. Stoichiometric reaction of Pt(1,5-cod) 2 (cod cyclooctadiene) with 7 a yielded the novel trimetallic 1-stanna-2-platina[2]ferrocenophane Fe(h-C 5 H 4 ) 2 Pt(1,5-cod)SntBu 2 (9), which functioned as a sluggish catalyst for the ROP of 7 a and 7 b.