EPR and ESI-MS/MS evidence is presented that in the absence of an olefinic substrate the reaction between the MnIII(salen) complexes A1 (X = Cl) and A2 (X = PF6) and PhIO or NaOCl as oxygen sources leads to paramagnetic MnIV(salen) complexes. Depending on the solvent and the counterion, two distinct MnIV(salen) complexes intervene. In CH2Cl2, regardless of the counterion, a ClOMnIV(salen) complex (B1) and a HOMnIV(salen) complex (B1‘) are formed by Cl and H atom abstraction from CH2Cl2, and the latter deprotonates to the neutral OMnIV(salen) complex (B2). In EtOAc as solvent, only the complex B2 is obtained from A1 (X = Cl), presumably by inner-sphere electron transfer from the chloride ion. The MnIV(salen) complexes display the following reaction modes toward 1,2-dihydronaphthalene (1), styrene (2), and the radical probe 3 as substrates:  Complex B1 chlorinates the olefins 1/2 through an electrophilic pathway to yield the 1,2-dichloro adducts 1a/2a and the chlorohydrins 1b/2b (nucleophilic trapping of the initially formed benzylic cation), while with olefin 3 the ring-opened dichloro product 3a results. Complex B2, however, epoxidizes these olefins through a radical pathway, as evidenced by the formation of isomerized stilbene oxide 4c (cis/trans ratio 36:64) from cis-stilbene (4). The relevance of these paramagnetic MnIV(salen) species in Jacobsen−Katsuki catalytic epoxidations is scrutinized.

The enzyme Coprinus peroxidase (CiP) was employed for the kinetic resolution of racemic hydroperoxides 1 and the asymmetric sulfoxidation of prochiral sulfides 4. Eleven hydroperoxides 1a-k were reduced by CiP and guaiacol as reductant under conditions of kinetic resolution with enantioselectivities of up to >98% for the (S)-hydroperoxide 1 and 90% for the (R)-alcohol 2. In the absence of a reductant, the hydroperoxide 1a afforded with CiP enantiomerically enriched hydroperoxide 1a (ee up to 54%) and alcohol 2a (ee up to 40%), as well as ketone 3a (which is also formed simultaneously in all other reactions) and molecular oxygen. Catalase activity was established for CiP with hydrogen peroxide. When aryl alkyl sulfides 4 were used as oxygen acceptors, three products, sulfoxides 5, alcohols 2, and hydroperoxides 1, were obtained, all in enantiomerically enriched form. The highest ee value (89%) was achieved for the sulfoxide derived from naphthyl methyl sulfide (4f). Thus, CiP may be utilized for the asymmetric synthesis of optically active hydroperoxides 1, alcohols 2, and sulfoxides 5.

Mono- and dinuclear hydroxopalladium complexes (kappa 2-TpiPr2,X)(py)Pd-OH (1; X = H, Br) and (mu-OH)2[Pd(kappa 2-TpiPr2)(H2O)]2 (2) are prepared by base hydrolysis of the corresponding chloride complexes (kappa 2-TpiPr2,X)(py)Pd-Cl (3) and (mu-Cl)2[Pd(kappa 3-TpiPr2)]2 (4), respectively. Functionalization of the OH part in 1 is effected via dehydrative condensation with protic substrates (H-A) to give a series of substituted products, (kappa 2-TpiPr)(py)Pd-A (5), and treatment of the dinuclear complex 2 with excess acetic acid affords the mononuclear diacetato complex 6, (kappa 2-TpiPr2-H)Pd(OAc)2(HOAc). Complexes 1-4 and 6 have been characterized crystallographically, and it is revealed that complexes 2 and 6 involve cyclic hydrogen-bonding interaction among the nitrogen atom of the pendent noncoordinated pyrazolyl group, the hydrogen atom in the protic part of the ligand (OH, AcOH), and, in the case of 2, an external water molecule.

Newly developed polymerisable nematic liquid crystalline materials in the Paliocolor® family with medium and high birefringence (0.16 and 0.20, respectively) are described. They enable the manufacturing of optical films, such as retardation films, brightness enhancement films and color filters, with superior quality and extremely reduced thickness by using coating techniques.