Herein, we report a semiconductive, proton-conductive, microporous hydrogen-bonded organic framework (HOF) derived from phenylphosphonic acid and 5,10,15,20-tetrakis[pphenylphosphonic acid] porphyrin (GTUB5). The structure of GTUB5 was characterized using single crystal X-ray diffraction. A narrow band gap of 1.56 eV was extracted from a UV-Vis spectrum of pure GTUB5 crystals, in excellent agreement with the 1.65 eV band gap obtained from DFT calculations. The same band gap was also measured for GTUB5 in DMSO. The proton conductivity of GTUB5 was measured to be 3.00 × 10 −6 S cm −1 at 75°C and 75% relative humidity. The surface area was estimated to be 422 m 2 g −1 from grand canonical Monte Carlo simulations. XRD showed that GTUB5 is thermally stable under relative humidities of up to 90% at 90°C. These findings pave the way for a new family of organic, microporous, and semiconducting materials with high surface areas and high thermal stabilities.

The reactions of the monopentafulvene complexes Ti1a and Ti1b with the general formula [Cp*Ti(Cl)(π-η 5 :σ-η 1 -C 5 H 4 CR 2 )] (R = p-tolyl (Ti1a); CR 2 = adamantylidene (Ti1b)) with the bidentate P,O-ligand precursor L1, featuring a diphenylphosphine and a hydroxyl functional group, are reported, yielding the corresponding complexes Ti2a and Ti2b in good yields as the result of deprotonation. A chloride/methyl exchange reaction and subsequent reaction with B(C 6 F 5 ) 3 was envisaged to yield the corresponding cationic complexes. Instead, the methylation reactions of Ti2a and Ti2b with methyllithium or methylmagnesium bromide selectively yielded the doubly methylated titanium complexes Ti3a and Ti3b with abstraction of LiCl and the lithium salt of the bidentate P,O-ligand. To avoid this reaction, the P,O-ligand precursor L2 was prepared, featuring a carbonyl group instead of the hydroxyl functional group. This change in the general reaction sequence allowed the preparation of a new family of cationic titanium complexes Ti6a and Ti6b and was transferred to the heavier congeners zirconium (Zr4) and hafnium (Hf4). Every step of the reaction pathway was performed under mild reaction conditions and in good to very good yields. The insertion of the carbonyl group into the M−C exo bond of the monopentafulvene complexes Ti1a, Ti1b, Zr1, and Hf1, and consequently the formation of a C−C bond, proved to be mandatory for the methylation and subsequent abstraction of the methyl group by B(C 6 F 5 ) 3 . In effect, a tridentate Cp,O,P-ligand was directly introduced into the coordination spheres of the respective group 4 metals within the cationic complexes. In all cases the phosphorus shows a persistent interaction between the Lewis acidic metal center and the Lewis basic phosphine moiety, as shown by NMR analyses and in the solid state. Every complex was thoroughly characterized, including several X-ray diffraction analyses of each class of compounds reported here.

<p>We report the first semiconductive, proton-conductive, microporous hydrogen-bonded organic framework (HOF) derived from phenylphosphonic acid and 5,10,15,20‐tetrakis[<i>p</i>‐phenylphosphonic acid] porphyrin (known as GTUB5). The structure of GTUB5 was characterized using single crystal X-ray diffraction (XRD). A narrow band gap of 1.56 eV was extracted from a UV-Vis spectrum of pure GTUB5 crystals, in excellent agreement with the 1.65 eV band gap obtained from density functional theory calculations. The same band gap was also measured for GTUB5 in DMSO. The proton conductivity of GTUB5 was measured to be 3.00 ´ 10^-6S cm^-1 at 75 °C and 75 % relative humidity. The surface area of GTUB5’s hexagonal voids were estimated to be 422 m² g^-1 from grand canonical Monte Carlo simulations. XRD showed that GTUB5 is thermally stable under relative humidities of up to 90 % at 90 °C. These findings pave the way for a new family of microporous, organic, semiconducting materials with high surface areas and high thermal stabilities. Such materials could find applications in printed electronics, optoelectronics, and electrodes in supercapacitors.<br></p>

The reactions of monopentafulvene complexes Ti1, Zr1, and Hf1 with bidentate O,P-ligand precursors L1-L3 to form the corresponding cationic complexes employing an established three-step synthetic protocol [insertion, methylation, activation with B(C 6 F 5 ) 3 ] are investigated. Ligands L1-L3 are designed to have different sized spacers between the carbonyl and diphenylphosphine functional groups. The attempts to react Ti1, Zr1, and Hf1 with acetyldiphenylphosphine (L1) proved to yield undesired products at various steps in the synthetic sequence. When Ti1 is used, Ti2 is formed and diphenylphosphine is released at the same time. Compound Ti2, with the exocyclic double bond, is the formal product of insertion of the smallest ketene (H 2 C=C=O) into the Ti-C exo bond. Starting with [a] 5146 Scheme 2. Targeted cationic group 4 metal complexes of this work. 5147 isolation and purification steps before synthesizing the corresponding complexes. In contrast, our approach allows the preparation of densely functionalized Cp,D,P-tridentate ligands directly in the coordination sphere of the respective group 4 metals in good to excellent yields and under mild reaction conditions. [11,12] As a continuation of our efforts, we herein report on limitations and possibilities to expand and modify the tridentate Cp,O,P-ligand framework of this family of cationic complexes with focus on the ring size of the resulting M,O,P-heterocycles (Scheme 2). Results and Discussion Attempts to Synthesize Cationic Group 4 Metal Complexes with Four-Membered M,O,C,P-UnitsScheme 5. Synthesis of complexes Zr2 and Hf2. 5149Scheme 8. Three-step synthesis of cationic group 4 metal complexes Ti6, Zr6, and Hf6 by reacting monopentafulvene complexes Ti1, Zr1, and Hf1 with L2, subsequent methylation and final activation with B(C 6 F 5 ) 3 . Synthesis of Hf5:To a solution of complex Hf4 (0.200 g, 0.232 mmol) in 15 mL of tetrahydrofuran was added a methyllith-

Previous work found the gas hold-up in a tall, 0.15 m 3 vessel, agitated by three impellers, to decrease considerably with temperature. This was attributed to either a decrease in liquid viscosity, a decrease in surface tension or a decrease in gas density. The aim of this work was to investigate the influence of gas density on the gas hold-up. First of all, it was attempted to reproduce the data found in literature. It was shown that contaminants had a significant impact on the gas hold-up. Experiments with increasing and decreasing amounts of tap water (as source of the contamination) found the gas hold-up to be affected by a strongly absorbing nonionic surface active agent. Experiments in a system exhibiting low conductivity and low gas hold-up showed that the gas hold-up decreased 15 % for temperatures between 295 K and 350 K. Experiments with helium as sparging gas found that gas density does have a lowering effect on the gas hold-up. The gas hold-up increased again for temperatures above 350 K, which may be due to the increased presence of micro-bubbles in a near-boiling system.