Artificial enzymes are required to catalyse non-natural reactions. Here, a hybrid catalyst was developed by embedding a novel Ru complex in the transport protein NikA. The protein scaffold activates the bound Ru complex to produce a catalyst with high regio- and stereo-selectivity. The hybrid efficiently and stably produced α-hydroxy-β-chloro chlorohydrins from alkenes (up to 180 TON with a TOF of 1050 h).

Stable ruthenium-allenylidene complexes based on pentacenequinone have been synthesized. The complexes show an electronic absorption in the NIR region that arises from [a] 5181 forbidden MLCT transitions, as explained by DFT calculations. The crystal structure reveals promising features for the formation of metal-influenced organic FETs.

The syntheses of the two dicarbonyl complexes [Ru(bdmpza)Cl(CO)2] (3) and [Ru(2,2-bdmpzp)Cl(CO)2] (4), bearing a bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) or a 2,2-bis(3,5-dimethylpyrazol-1-yl)propionato (2,2-bdmpzp) scorpionate ligand, are described. Both complexes are obtained by reacting the polymer [RuCl2(CO)2] n with either K[bdmpza] or K[2,2-bdmpzp]. Reaction of the acid Hbdmpza with [Ru3(CO)12] results in the formation of two structural isomers of a hydrido complex, [Ru(bdmpza)H(CO)2] (5a,b). Under aerobic conditions conversion of [Ru(bdmpza)H(CO)2] (5a,b) to form the Ru(I) dimer [Ru(bdmpza)(CO)(μ-CO)]2 (6) seems to be hindered in comparison to the case for the η5-C5H5 (Cp) analogues. Dimer 6 is obtained via a reaction of Hbdmpza with catena-[Ru(OAc)(CO)2] n instead. The molecular structures of 3, 4, and 6 have been obtained by single-crystal X-ray structure determinations. The precatalytic properties of the two dicarbonyl complexes 3 and 4 toward the catalytic oxidation of cyclohexene with different oxidizing agents are discussed as well.

A series of ruthenium allenylidene complexes bearing polyaromatic substituents have been prepared starting from [Ru(bdmpza)Cl(PPh 3 ) 2 ] (1) (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetato). Reacting 1 with 1,1-bis(3,5-ditert-butylphenyl)-1-methoxy-2-propyne results in the formation of two structural isomers of an allenylidene complex [Ru(bdmpza)Cl(CCC(Ph t Bu 2 ) 2 )(PPh 3 )] (5A/5B), as well as the related carbonyl complex [Ru(bdmpza)Cl(CO)-(PPh 3 )] (4A/4B). Conversion of 9-ethynyl-9-fluorenol leads to the corresponding allenylidene complex [Ru(bdmpza)Cl(CC(FN))(PPh 3 )] (7A/7B) (FN = fluorenyl). Based on anthraquinone, a new synthetic route toward 10-ethynyl-10-hydroxyanthracen-9-one via the trimethylsilyl-protected propargyl alcohol is described, and subsequent conversion of this compound to the allenylidene complex ([Ru(bdmpza)Cl(C C(AO))(PPh 3 )] (12A/12B) (AO = anthrone) is reported. The synthetic route from 7H-benzo[no]tetraphen-7-one to the propargyl alcohol 7-ethynyl-7H-benzo[no]tetraphen-7-ol is described, which is followed by the transformation into the allenylidene complex [Ru(bdmpza)Cl(CC(BT))(PPh 3 )] (17A/17B) (BT = benzotetraphene). The molecular structures of 4B, 7A, 7B, 12A, 12B, 13A, and 17A have been characterized by single-crystal X-ray crystallography, and these analyses suggest that 17A might function as a "metal-tuned organic field effect transistor". The electrochemical properties of the allenylidene complexes have been studied via cyclic voltammetry, and time-dependent DFT calculations have been conducted to assign weak absorptions in the NIR region to forbidden MLCT transitions. ■ INTRODUCTIONOrganometallic complexes containing allenylidene moieties are of considerable interest due to their characteristic chemical and physical properties. 1 The synthesis of cumulene based complexes has benefited immensely from the methodology published by Selegue. 2 The reaction of substituted propargyl alcohols with a variety of ruthenium based metal complexes allows for the direct formation of ionic and neutral complexes, and this has dramatically simplified the synthetic demand for such work. π-Conjugated systems based on ruthenium are important in systems that allow exchange of electrons via the cumulenylidene unit between remote terminal groups, 3 thus leading to interesting properties and potential applications in molecular-scale electronic, magnetic, and optical devices. 4 Special attention has been put on dinuclear compounds that can communicate along the allenylidene unit. The linking between the two metal centers can be achieved either via functionalization of the allenylidene with nitrogen based donor substituents, as in the bis(pyridyl)allenylidene−ruthenium(II) complex trans-[Cl(16-TMC)RuCCC(2-py) 2 ] + 5,9,5,9, py = pyridyl), 5 or via all carbon linked systems such as trans-[Cl(dppe) 2 Ru−CC−C(CH 3 )C(H)−C(CH 3 )CC Ru(dppe) 2 Cl]BF 4 , which results from the coupling of the diynyl and allenylidene moieties. 6 Nevertheless, classical mononuclear ruthenium allenylide...