DOI: 10.1002/chem.201200953 Cyclic and Linear Polyferrocenes with Silicon and Tin as Alternating Bridges Bidraha Bagh, [a] Nora C. Breit, [a] Subhayan Dey, [a] Joe B. Gilroy, [b] Gabriele Schatte, [c] Klaus Harms, [d] and Jens Müller* [a] Introduction Since the discovery that the thermal ring-opening polymeri- zation (ROP) of sila[1]ferrocenophanes 1a and 1b results in high-molecular-weight polymers, [1] the field of metallopoly- mers has been extended to various transition metals and bridging elements. [2] Poly(ferrocenylsilane)s, in particular compound 2a, are one of the most-studied metallopolymers and have been used in various applications, for example, as precursors to ceramics, [3] as tunable component of photonic crystals displays, [4] and as redox-tunable capsules. [5] The living anionic ROP of sila[1]ferrocenophanes allows excel- lent control over the molecular weights of the block copoly- mers, which have recently been shown to self-assemble into block-selective solvents to give nanoscopic aggregates of dif- ferent morphologies. [6] Half a century ago, Nesmeyanov and Kritskaya first re- ported the synthesis of [1.1]ferrocenophanes ([1.1]FCPs ; Figure 1); [7] these ferrocene derivatives were bridged by carbon atoms and were later confirmed as syn isomers. [8] The first anti isomer of a dicarbaACHTUNGTRENNUNG[1.1]ferrocenophane was structurally characterized a few decades later. [9] Since the synthesis of the first [1.1]FCPs in 1956, [7] this family of com- pounds has grown significantly with the incorporation of B, [10] Al, [11] Ga, [11b, 12] In, [11b, 13] Si, [14] Sn, [15] Pb, [16] P, [17] As, [18] S, [19] Zn, [20] and Hg [21] atoms as heteroatom bridges. In addi- tion to these [1.1]FCPs, other [1.1]metallacyclophanes have been synthesized, such as [1.1]ruthenocenophanes, [14a, 22] [1.1]chromarenophanes, [23] [1.1]molybdarenophanes, [23] and mixed [1.1]metallacyclophanes [22] that contained Fe/Ru or Fe/Co metal combinations. In contrast to [1]metallacyclo- phanes, their formal dimers lack ring strain and no report of Abstract: The synthesis and characteri- zation of ferrocene-based oligomers that contained two different elements (Si and Sn) as alternating bridges is de- scribed for the first time. The salt- metathesis reaction of R 2 SiACHTUNGTRENNUNG[(C 5 H 4 )Fe- ACHTUNGTRENNUNG(C 5 H 4 Li)] 2 (R = Me, Et) with R’ 2 SnCl 2 (R’ = Me, nBu, tBu) afforded a mixture of oligomers (6 Me SnMe 2 , 6 Et SnMe 2 , 6 Me SnnBu 2 , 6 Et SnnBu 2 , 6 Me SntBu 2 , and 6 Et SntBu 2 ). These oligomers were char- acterized by 1 H, 13 C, 29 Si, and 119 Sn NMR spectroscopy and by mass spectrometry. MS (MALDI-TOF) stud- ies of 6 Et SnMe 2 revealed the presence of linear (l) and cyclic (c) species that contained up to 20 ferrocene moieties. The molecular weights of the polymers were determined by gel-permeation chromatography (GPC) and by dynam- ic-light scattering (DLS). GPC analysis revealed average molecular weights of 2100–6300 Da with respect to polystyr- ene as a standard. DLS analysis yielded very similar results. Some compounds, c-(6 Me SnMe 2 ) 1 , c-(6 Me SntBu 2 ) 2 , c- (6 Et SnMe 2 ) 1 , c-(6 Et SntBu 2 ) 2 , l- (6 Me SnnBu 2 ) 2 , and l-(6 Me SnnBu 2 ) 3 , which contained up to six ferrocene moieties, were isolated in their pure form either by column chromatography or by crystallization. The Si- and Sn- bridged macrocycles that contained four ferrocene units (c-(6 Me SntBu 2 ) 2 and c-(6 Et SntBu 2 ) 2 ) were structurally characterized by single-crystal X-ray analysis. Keywords: ferrocene · macrocycles · metallocenes · silicon · tin [a] B. Bagh, N. C. Breit, S. Dey, Prof. Dr. J. Müller Department of Chemistry, University of Saskatchewan 110 Science Place, Saskatoon Saskatchewan S7N 5C9 (Canada) Fax: (+ 1) 306-966-4730 E-mail: jens.mueller@usask.ca [b] Dr. J. B. Gilroy School of Chemistry, University of Bristol Bristol BS8 1TS (UK) [c] Dr. G. Schatte Saskatchewan Structural Sciences Centre University of Saskatchewan 110 Science Place, Saskatoon Saskatchewan S7N 5C9 (Canada) [d] Dr. K. Harms Fachbereich Chemie, Philipps-Universität Marburg Hans-Meerwein-Strasse, 35032 Marburg (Germany) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201200953. Figure 1. [1]Ferrocenophanes (1a, 1b), poly(ferrocenylsilane)s (2a, 2b), and [1.1]ferrocenophanes.  2012 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim Chem. Eur. J. 2012, 18, 9722 – 9733 9722