A polyradical consisting of alternating triarylamine and perchlorotriphenylmethyl radical moieties was synthesized by Horner-Emmons reaction. This compound is the first polymeric neutral mixedvalence compound that shows an intervalence charge transfer (IV-CT) band in the NIR. Comparison of the absorption spectra of the polymer with those of a reference monomer shows that the IV-CT transition is confined to one repeating unit. HOMO and LUMO levels are at -5.5 and -4.5 eV vs vacuum, respectively, as estimated by cyclic voltammetry. A very low exciton binding energy is indicated by comparison with the optical band gap (1.2 eV). The electron transfer properties of the polymer were investigated in solution by fs-pump-probe transient absorption spectroscopy. After optical excitation, the polymer shows a biexponential decay in the ps time regime. The short-living, solvent-dependent component refers to the direct decay from the IV-CT state to the ground state and the long-living, solvent-independent component is tentatively attributed to an equilibrium formation of the IV-CT state and a completely charge separated state. The charge-transport properties were investigated in films in organic field-effect transistor (OFET) devices. Electron and hole mobilities are both about 3 Â 10 -5 cm 2 V -1 s -1 , demonstrating ambipolar transport behavior of the polymer.

The triarylborane acceptor in poly[9-((4-dimesitylboryl)-3,5-dimethylphenyl)-9H-carbazole]-3,6diyl P2 has a strong impact on the optical properties of this 3,6-linked carbazole main chain polymer and results in an enhanced fluorescence quantum yield because of a low-lying fluorescent CT state. In contrast, the same acceptor substituent does not influence the optical properties of poly[9-((4-dimesitylboryl)-3,5-dimethylphenyl)-9H-carbazole]-2,7-diyl P1. In the latter polymer, the optical properties are governed by conjugation along the carbazole backbone. This interpretation is supported by comparison with poly[9-(4-(diphenylmethyl)-phenyl)-9H-carbazole]-2,7-diyl P3, which serves as a reference polymer. Synthesis and characterization by gel permeation chromatography, NMR spectroscopy, absorption, and fluorescence measurements in solution and solid state and cyclic voltammetric measurements of the three polymers are presented.

During the last two decades, boron compounds have become established as versatile reagents in organic synthesis, and different methods have been developed for their preparation. Along with hydroboration, [1][2][3][4] transition-metalcatalyzed diboration [5] has become useful for the functionalization of unsaturated organic compounds. [6,7] This reaction is widely applicable to substrates such as alkynes [8,9] arynes, [10] alkenes, [11][12][13] carbenoids, [14,15] as well as diazo [16] and carbonyl compounds. [17][18][19][20] Although bis(catecholato)diborane(4) and bis(pinacolato)diborane(4) represent by far the most commonly employed diborane(4) species, the reaction is not restricted to their use. For instance, several diboranes(4) with interesting properties are derived from [2]borametalloarenophanes. The first example of this class of organometallic compound, the [2]boraferrocenophane 1, was prepared by Herberhold, Wrackmeyer and co-worker, [21] while the molecular structure along with an alternative synthesis was published by our group.[22] Subsequently, a series of [2]borametalloarenophanes has appeared. [23-28b] These ansa complexes show tilted molecular structures, thus featuring significant molecular strain. In 2006, we successfully exploited this ring strain in oxidative addition reactions of [2]borametalloarenophanes to low-valent platinum centers, affording[3]diboraplatinametalloarenophanes. In addition, we demonstrated the suitability of [2]borametalloarenophanes as diboranes(4) in the platinum-mediated diboration of alkynes to form [4]diboradicarbametalloarenophanes.[29] By expansion of this strategy, we also achieved the diboration of diazo compounds [16] and isocyanides.[30]Herein, we report on the two diastereomeric [4]diboradicarbaferrocenophanes 4 and 5, which were obtained by double diboration of the conjugated dialkyne 3 either by a platinum-mediated route employing the [2]boraferrocenophane 1 in the presence of [PtA C H T U N G T R E N N U N G (PEt 3 ) 3 ], or stoichiometrically by using the [3]diboraplatinaferrocenophane 2, directly (Scheme 1). In contrast to related transformations of monoalkynes, [29] monitoring the reaction progress by multinuclear NMR spectroscopy revealed the gradual disappearance of the starting materials, and the formation of two distinct compounds in benzene solution at elevated temperatures. Both species feature similar resonances in the 1 H, 11 B, and 13 C NMR spectra, which we rationalized by the generation of diastereomeric species. Complexes 4 and 5 were eventually isolated after workup as orange, moderately moisture-sensitive powders. The NMR spectroscopic data of both diastereomers are fully consistent with the presence of doubly bis(borylated), conjugated triene systems bearing two ferro-