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Titanocene dichloride, [Ti]Cl2 (1) ([Ti] = Ti(η5-C5H4SiMe3)2), with one equiv. of the lithium thiolates LiSCHR-2-cC4H3S (2a, R = H; 2b, R = Me) gave the appropriate [Ti](Cl)(SCHR-2-cC4H3S) compounds (3a, R = H; 3b, R = Me) under mild reaction conditions. Further treatment of 3a,b with another equiv. of thiolates 2a,b produced the respective bis(thiolates) species [Ti](SCHR-2-cC4H3S)2 (4a,b). Titanocenes 4a,b are also accessible, when 1 is reacted with 2a,b in a 1:2 M ratio. The hydrolysis reaction of 4a,b produced the titanoxane cluster 5, consisting of a [Ti′]6O9 cage ([Ti′] = Ti(η5-C5H4SiMe3)) with a silsesquioxane analog structure. The molecular structure of 5 in the solid state is the first example of a trigonal prismatic Ti6-polyhedron. Upon treatment of 4a,b with MCl2 (M = Pd, Pt), aiming to obtain heterobimetallic coordination complexes, however, either 1 or 3a,b were formed, depending on the reaction conditions. All the compounds have been characterized by elemental analysis, IR, NMR (1H, 13C{1H}) spectroscopy and mass-spectrometry.

Treatment of Ti(η 5-1-SiMe3C9H6)Cl3 (1) with LiOR (2a, R = 2,6-tBu2C6H3; 2b, R = 2,6-Ph2C6H3; 2c, R = iC3H7; 2d, R = tC4H9) in a 1:1 M ratio produced half-sandwich compounds Ti(η 5-1-SiMe3C9H6)(Cl)2(OR) (3a, R = 2,6-tBu2C6H3; 3b, R = 2,6-Ph2C6H3; 3c, R = iC3H7; 3d, R = tC4H9) in high yield. Compounds 3c,d were also accessible, when 1 was reacted with a onefold excess of HOR (2c, R = iC3H7; 2d, R = tC4H9) in refluxing benzene. The molecular structure of 3b in the solid state was determined by single-crystal X-ray diffraction studies, confirming the piano-stool geometry. Quantum chemical calculations at the B3LYP/6-31g(d)+LANL2DZ level of theory were carried out for 1 and 3a–d in order to better understand and rationalize the nature of bonding and thus demonstrate the effect of different substituents on the structural and electronic properties in these compounds. The studies reveal a high electron density on the Ti(IV) ion for 3c and 3d as compared to 3a and 3b, and also showed the possibility of controlling and fine tuning the electron density on the Ti(IV) ion through the introduction of different alkyloxy or aryloxy substituents.

Heterobimetallic {cis-[Pt](μ-σ,π-C CPh)2}[Cu(N CMe)]BF4 (3a: [Pt] = (bipy)Pt, bipy = 2,2′-bipyridine; 3b: [Pt] = (bipy′)Pt, bipy′ = 4,4′-dimethyl-2,2′-bipyridine) is accessible by the reaction of cis-[Pt](C CPh)2 (1a: [Pt] = (bipy)Pt, 1b: [Pt] = (bipy′)Pt]) with [Cu(N CMe)4]BF4 (2). Substitution of N CMe by PPh3 (4) can be realized by the reaction of 3a with 4, whereby [{cis-[Pt](μ-σ,π-C CPh)2}Cu(PPh3)]BF4 (5) is formed. On prolonged stirring of 3 and 5, respectively, N CMe and PPh3 are eliminated and tetrametallic {[{cis-[Pt](η2-C CPh)2}Cu]2}(BF4)2 (6) is produced. Addition of an excess of N CMe to 6 gives heterobimetallic 3a. When instead of N CMe or PPh3 chelating molecules such as bipy (7) are reacted with 3a then the heterobimetallic π-tweezer molecule [{cis-[Pt](μ-σ,π-C CPh)2}Cu(bipy)]BF4 (8) is formed. Treatment of 8 with another equivalent of 7 produced [Cu(bipy2)]BF4 (9) along with [Pt](C CPh)2. However, when 3b is reacted with 1b in a 1:1 molar ratio then 10 and 11 of general composition [{[Pt](C CPh)2}2Cu]BF4 are formed. These species are isomers and only differ in the binding of the PhC C units to copper(I). A possible mechanism for the formation of 10 and 11 is presented. The solid state structures of 6, 10 and 11 are reported. In 11 the [{cis-[Pt](μ-σ,π-C CPh)2}2Cu]+ building block is set-up by two nearly orthogonal positioned bis(alkynyl) platinum units which are connected by a Cu(I) ion, whereby the four carbon–carbon triple bonds are unsymmetrical coordinated to Cu(I). In trimetallic 10 two cis-[Pt](C CPh)2 units are bridged by a copper(I) center, however, only one of the two PhC C ligands of individual cis-[Pt](C CPh)2 fragments is η2-coordinated to Cu(I) giving rise to the formation of a [(η2-C CPh)2Cu]+ moiety with a linear alkyne–copper–alkyne arrangement (alkyne = midpoint of the C C triple bond). In 6 two almost parallel oriented [Pt](C CPh)2 planes are linked by two copper(I) ions, whereby two individual PhC C units, one associated with each Pt building block, are symmetrically π-coordinated to Cu.

A convenient synthesis method was developed for the preparation of C-stapled homodimeric bis-lexitropsins connected through the nitrogen atoms of the central pyrrole ring with a bis-methylene linker. This lexitropsin is designed as a standard for other bis-lexitropsins with longer chains in biological evaluation and NMR studies. The key step in this method is the treatment of ethyl 4-nitropyrrole-2-carboxylate with flame-dried potassium carbonate in DMF followed by the addition of 1,2-dibromoethane to form the 1,2-dipyrroloethane derivative.

The electronic interaction between the iron atom and the indenyl ligands with one and two trimethylsilyl substituents in different isomeric positions in bis(indenyl)iron has been studied using cyclic voltammetry and UV–vis spectroscopy. Results and interpretation are supported by theoretical PM3-calculations.

The synthesis of the bis(η5-indenyl)iron sandwich complexes (η5-1-SiMe3–C9H6)2Fe (3a), (η5-2-SiMe3–C9H6)2Fe (3b), [η5-1,2-(SiMe3)2C9H5]2Fe (4a) and [η5-1,3-(SiMe3)2C9H5]2Fe (4b), by the reaction of the appropriate lithium indenide salts [prepared from 1-SiMe3–C9H7 (2a), 2-SiMe3–C9H7 (2b), 1,2-(SiMe3)2C9H6 (2c) or 1,3-(SiMe3)2C9H6 (2d)] with ferrous chloride (1) in a 2:1 molar ratio is discussed. The solid-state structure of 4b was determined by single-crystal X-ray diffractometry. Complex 4b exists in a gauche conformation, showing that the indenyl ligands are sterically imposed by the bulk of the Me3Si substituents. The average Fe–C distance is 2.091(3) A. Cyclovoltammetric studies indicate that 3 and 4 are redox-active with one-electron oxidations [E1/2=−270 to −360 mV versus Fc/Fc+, Fc=(η5-C5H5)2Fe].

The preparation of the shape-persistent carbosilane-functionalized porphyrins H2TPP(4-SiRR’Me)4, Zn(II)- TPP(4-SiRR’Me)4 (R = R’ = Me, CH2CHvCH2, CH2 CH2CH2OH; R = Me, R’ = CH2 CHvCH2, CH2CH2CH2OH; TPP = tetraphenyl porphyrin), H2TPP(4-Si(C6H4-1,4-SiRR’Me)3)4, and Zn(II)-TPP(4-Si- (C6H4-1,4-SiRR’Me)3)4 (R = R’ = Me, CH2CHvCH2; R = Me, R’ = CH2CHvCH2) using the Lindsey condensation methodology is described. For a series of five samples their structures in the solid state were determined by single crystal X-ray structure analysis. The appropriate 0th and 1st generation porphyrin-based 1,4-phenylene carbosilanes form 2D and 3D supramolecular network structures, primarily controlled by either π–π interactions (between pyrrole units and neighboring phenylene rings) or directional molecular hydrogen recognition and zinc–oxygen bond formation in the appropriate hydroxyl-functionalized molecules. UV-Vis spectroscopic studies were carried out in order to analyze the effect of the dendritic branches on the optical properties of the porphyrin ring. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

The asymmetrical titanocene dichloride (1,3- t Bu 2 C 5 H 3 )( t Bu 2 C 5 H 4 )TiCl 2 ( I ) has been prepared from (1,3- t Bu 2 C 5 H 3 )TiCl 3 and ( t BuC 5 H 4 )Li. The reactions of I and of (1,3- t Bu 2 C 5 H 3 ) 2 TiCl 2 with an excess of ammonium thiocyanate afforded the S-bonded thiocyanato complexes (1,3- t Bu 2 C 5 H 3 )( t BuC 5 H 4 )Ti(SCN) 2 ( IV ) and (1,3- t Bu 2 C 5 H 3 ) 2 Ti(SCN) 2 ( V ) respectively. A similar reaction of ( t BuC 5 H 4 ) 2 TiCl 2 with excess anmmonium thiocyanate produced the S-bonded thiocyanato complex ( t Bu C 5 H 4 ) 2 Ti(SCN) 2 ( II ) as a minor product and the N-bonded thiocyanato complex ( t BuC 5 H 4 ) 2 Ti(NCS) 2 ( III ) as the major product. Similar reaction of ( t BuC 5 H 4 ) 2 TiCl 2 with ammonium thiocyanate in 1 : 1 molar ratios gave ( t BuC 5 H 4 ) 2 Ti(Cl)(NCS) ( VI ). Crystal structure of III was determined.

The compounds (1,3-tBu2C5H3)2TiCl2 (I) and (1,3-tBu2C5H3)TiCl3 (II) were prepared in good yields from TiCl4 and (1,3-tBu2-C5H3)Li. Reactions of II with methanol, ethane-1,2-diol, sodium oxalate, and 2-pyrazine carboxylic acid afforded various organotitanium complexes. The crystal structure of II was determined.