Ferrocene-based tris(1-pyrazolyl)borates: a new approach to heterooligometallic complexes and organometallic polymers containing transition metal atoms in the backbone.

Starting from mono- and bifunctional ferrocene-based tris(1-pyrazolyl)borates, a novel route to oligonuclear complexes is presented, which incorporates transition metal centers differing substantially in their chemical nature. Both binuclear organometallics FcB(pz)3MLn (Fc:  ferrocenyl. pz:  1-pyrazolyl. MLn:  Tl, 1-Tl; Mo(CO)3Li, 1-MoLi; Mo(CO)2(η3-methylallyl), 1-Mo; ZrCl3, 1-Zr) and trinuclear complexes 1,1‘-fc[B(pz)3MLn]2 (fc:  ferrocenylene. MLn:  Tl, 2-Tl; Mo(CO)3Li, 2-MoLi; Mo(CO)2(η3-methylallyl), 2-Mo) have been prepared. The trinuclear compound [FcB(4-SiMe3pz)3]2Fe, 1-FeSi, has been investigated as a model system for organometallic coordination polymers, consisting of the bifunctional linker 1,1‘-fc[B(pz)3]22- and transition metal ions Mn+. X-ray crystallography shows 1-Tl to establish a polymeric structure in the solid state, while 1-Mo features the usual tridentate coordination mode of the scorpionate ligand (C25H25BFeMoN6O2; a = 8.756(1) Å, b = 12.154(1) Å, c = 12.927(1) Å, α = 105.26(1)°, β = 102.29(1)°, γ = 105.09(1)°; triclinic space group P1̄; Z = 2). With the exception of 1,2-Tl, the anodic oxidation of the ferrocene moiety is generally reversible; cyclic voltammetry measurements indicate the two Mo centers in 2-Mo and the two Fc moieties in 1-FeSi to be noncommunicating

Exploring Structure-Property Relations of B,S-Doped Polycyclic Aromatic Hydrocarbons through the Trinity of Synthesis, Spectroscopy, and Theory

Polycyclic aromatic hydrocarbons (PAHs) are prominent lead structures for organic optoelectronic materials. This work describes the synthesis of three B,S-doped PAHs with heptacene-type scaffolds via nucleophilic aromatic substitution reactions between fluorinated arylborane precursors and 1,2-(Me3SiS)2C6H4/1,8-diazabicyclo[5.4.0]undec-7-ene (72-92% yield). All compounds contain tricoordinate B atoms at their 7,16-positions, kinetically protected by mesityl (Mes) substituents. PAHs 1/2 feature two/four S atoms at their 5,18-/5,9,14,18-positions; PAH 3 is a 6,8,15,17-tetrafluoro derivative of 2. For comparison, we also prepared the skewed naphtho[2,3-c]pentaphene-type isomer 4. The simultaneous presence of electron-accepting B atoms and electron-donating S atoms results in a redox-ambiphilic behavior; the radical cations [1•]+ and [2•]+ were characterized by electron paramagnetic resonance spectroscopy. Several low-lying charge-transfer states exist, some of which (especially S-to-B and Mes-to-B transitions) compete on the excited-state potential-energy surface. Consistent with the calculated state characters and oscillator strengths, this competition results in a spread of fluorescence quantum yields (2-27%). The optoelectronic properties of 1 change drastically upon addition of Ag+ ions: while the color of 1 in CH2Cl2 changes bathochromically from yellow to red (λmax from 463 to 486 nm; -0.13 eV), the emission band shifts hypsochromically from 606 to 545 nm (+0.23 eV), and the fluorescence quantum yield increases from 12 to 43%. According to titration experiments, higher order adducts [Agn1m]n+ are formed. As a suitable system for modeling Ag+ complexation, our calculations predict a dimer structure (n = m = 2) with Ag2S4 core, approximately linear S-Ag-S fragments, and Ag-Ag interaction. The computed optoelectronic properties of [Ag212]2+ agree well with the experimentally observed ones.publishe

Luminescent diazaborolyl-functionalized polystyrene

Kuhtz H, Cheng F, Schwedler S, et al. Luminescent diazaborolyl-functionalized polystyrene. ACS Macro Letters. 2012;1(5):555-559.We present two different procedures for the synthesis of poly[4-(1′,3′-diethyl-1′,3′,2′-benzodiazaborolyl)styrene] (3a) and poly[4-(1′,3′-diphenyl-1′,3′,2′-benzodiazaborolyl)styrene] (3b). The new polymers were fully characterized by GPC, multinuclear NMR, and elemental analysis. The thermal properties and stability were studied by DSC and TGA, and the optical characteristics were examined by absorption and time-resolved fluorescence spectroscopy. Remarkably high quantum yields of up to 77% were measured. In comparison to molecular species we found significantly shorter lifetimes, likely as a result of incorporation of the chromophores into the polymer structure