Reaction of [(eta5-C5H4Li)(eta7-C7H6Li)Cr]tmeda with a variety of dialkyl(dichloro)silanes in aliphatic solvents afforded the corresponding [1]silatrochrocenophanes. Structural characterization by X-ray diffraction analysis of the [1]silatrochrocenophanes bearing Me2Si, (iPr)2Si, and silacyclobutane bridges revealed tilt angles alpha of 15.56(12) degrees , 15.8(1) degrees , and 16.33(17) degrees , respectively. Analogously, a [2]silatrochrocenophane (6) was prepared in excellent yield by reaction of [(eta5-C5H4Li)(eta7-C7H6Li)Cr]tmeda with 1,2-dichloro-1,1,2,2-tetramethyldisilane. This complex also was characterized structurally and exhibited a tilt angle alpha of 2.60(15) degrees. The [1]silatrochrocenophane bearing the Me2Si bridge underwent facile and regioselective carbon-silicon bond cleavage with [Pt(PEt3)4] to give a very high yield of an oxidative addition product. The ring-opening polymerization of these novel [1]silatrochrocenophanes afforded ring-opened chromium-based polymers.

The heteroleptic sandwich complex [Cr(eta(5)-C5H5)(eta(7)-C7H7)] (trochrocene) was prepared by subsequent treatment of CrCl3 with NaCp and Mg in the presence of cycloheptatriene in yields of 40%. Selective dimetalation employing tBuLi/tmeda (N, N, N', N'-tetramethylethylenediamine) afforded the highly reactive species [Cr(eta(5)-C5H4Li)(eta(7)-C7H6Li)] x tmeda. An X-ray crystal-structure determination of its thf solvate revealed a symmetrical, dimeric composition in the solid state, that is, a formula of [Cr(eta(5)-C5H4Li)(eta(7)-C7H6Li)]2 x (thf)8, where the C5H4 moieties of both units are connected by two bridging lithium atoms. Addition of different element dihalides to the dilithio precursor facilitated the isolation of ansa complexes with boron and germanium in the bridging position. Structural characterization by X-ray diffraction studies on [Cr(eta(5)-C5H4)-BN(SiMe3)2-(eta(7)-C7H6)] and [Cr(eta(5)-C5H4)-GeMe2-(eta(7)-C7H6)] emphasized the strained character with tilt angles of 23.87(13) degrees and 15.07(17) degrees , respectively. In contrast, the isolation of the appropriate [1]stannatrochrocenophane failed because of the thermal lability of the resulting product. However, the corresponding 1,1'-disubstitued derivatives [Cr(eta(5)-C5H4R)(eta(7)-C7H6R)] (R = B(Cl)NiPr2, SiMe3, GeMe3, SnMe3) were obtained by reverse addition of the dilithio precursor to an excess of the element (di)halide. The unstrained nature was proven by a crystal structure analysis of the 1,1'-diborylated species. The electronic structure of these substituted trochrocene derivatives, as well as of the [2]bora and [n]sila congeners (n = 1, 2), was investigated by means of UV-vis spectroscopy and DFT methods. As a consequence of the strong electronic influence of the B-N pi-system on the LUMOs, the UV-vis studies revealed a complementary correlation of the lowest energy band maxima as a function of molecular distortion for the boron containing species on the one hand, and the boron-free compounds on the other hand. These trends were reproduced fairly well by time dependent DFT calculations.

A comprehensive investigation into the cooperative reactivity of two chemically complementary metal-complex fragments in early-late heterodinuclear complexes has been carried out. Reaction of the partially fluorinated tripodal amidozirconium complexes [HC-(SiMe2NR)3Zr(mu-Cl)2Li(OEt2)2] (R = 2-FC6H4: 2a, 2,3,4-F3C6H4: 2b) with K[CpM(CO)2] (M=Fe, Ru) afforded the stable metal-metal bonded heterodinuclear complexes [HC[SiMe2NR]3-Zr-MCp(CO)2] (3-6). Reaction of the dinuclear complexes with methyl isonitrile as well as the heteroallenes CO2, CS2, RNCO and RNCS led to insertion into the polar metal-metal bond. Two of these complexes, [HC[SiMe2N(2-FC6-H4)]3Zr(S2C)Fe(CO)2Cp] (9a) and [HC-[SiMe2N(2-FC2H4)]3Zr-(SCNPh)Fe(CO)2-Cp] (12), have been structurally characterized by a single crystal X-ray structure analysis, proving the structural situation of the inserted substrate as a bridging ligand between the early and late transition metal centre. The reactivity towards organic carbonyl derivatives proved to be varied. Reaction of the heterobimetallic complexes with benzyl and ethylbenzoate led to the cleavage of the ester generating the respective alkoxozirconium complexes [HC[SiMe2N(2-FC6H4)]3ZrOR] (R = Ph-CH2: 13a, Et: 13b) along with [CpFe-[C(O)Ph](CO)2], whereas the analogous reaction with ethyl formate gave 13b along with [CpFeH(CO)2]; this latter complex results from the instability of the formyliron species initially formed. Aryl aldehydes were found to react with the Zr-M complexes according to a Cannizzaro disproportionation pattern yielding the aroyliron and ruthenium complexes along with the respective benzoxyzirconium species. The transfer of the aldehyde hydrogen atom in the course of the reaction was established in a deuteriation experiment. [HC[SiMe2-N(2-FC6H4)]3Zr-M(CO)2Cp] reacted with lactones to give the ring-opened species containing an alkoxozirconium and an acyliron or acylruthenium fragment; the latter binds to the early transition metal centre through the acyl oxygen atom, as evidenced from the unusuallly low-field shifted 13C NMR resonances of the RC(O)M units. Ketones containing a-CH units react with the Zr-Fe complexes cooperatively to yield the aldol coupling products coordinated to the zirconium complex fragment along with the hydridoiron compound [CpFeH(CO)2], whereas 1,2-diphenylcyclopropenone underwent an oxygen transfer from the keto group to a CO ligand to give a linking CO2 unit and a cyclopropenylidene ligand coordinated to the iron fragment in [HC-[Si(CH3)2N(2,3,4-F3C6H2)]3Zr(mu-O2C)-Fe(CO)[C3Ph2)Cp] (19). The atom transfer was established by 17O and 13C labelling studies. Similar oxygen-transfer processes were observed in the reactions with pyridine N-oxide, dimethylsulfoxide and methylphenylsulfoxide.

ansa‐[2]Borabis(benzene)chromophane and ansa‐[2]boraferroarenophane were treated with alkynes in the presence of catalytic amounts of platinum or palladium/charcoal (see example) to afford the corresponding ansa‐bis(boryl)alkenes in excellent yields and without detectable side products. The use of Pt and Pd are the first examples of diboration reactions of alkynes to be conducted under heterogeneous conditions.

Reaction of [Cr(η 6 -C 6 H 5 Li) 2 ]‚tmen with (RR′)-NBCl 2 (R ) R′ ) SiMe 3 ; R ) R′ ) iPr; R ) SiMe 3 , R′ ) tBu) and B 2 Br 2 (NMe 2 ) 2 , respectively, in hexane yielded the strained [1]borachromoarenophanes [Cr{(η 6 -C 6 H 5 ) 2 -BNRR′}] (4a-c; R ) R′ ) SiMe 3 ; R ) R′ ) iPr; R ) SiMe 3 , R′ ) tBu) and [2]borachromoarenophanes [Cr-{(η 6 -C 6 H 5 ) 2 (BNMe 2 ) 2 }] (5), respectively, in moderate yields as dark red solids; compounds 4c and 5 were structurally characterized. 4c exhibits the largest arenearene tilt angle (26.6(3)°) reported for any [n]metalloarenophane.

Pyridine-phosphine ligands 1-5 have been used to prepare neutral nickel dichloride complexes, neutral methylpalladium chloride complexes, and cationic methylpalladium complexes. The ligands consist of a diphenylphosphine and a pyridine moiety and differ in the backbone connecting those donor groups. Nickel complexes 9-13 are paramagnetic complexes, and they were characterized by elemental analysis, high-resolution mass spectrometry, and, for 10 and 12, single-crystal X-ray diffraction. Neutral palladium complexes 14-18 were fully characterized. Single-crystal X-ray diffraction was performed on complexes 15 and 16, and variable-temperature NMR demonstrated that 16 exhibits slow inversion of the metallacycle. Cationic palladium species 19-23 were obtained from the neutral complexes after chloride abstraction. Like its neutral precursor, 21 showed slow ring inversion. The nickel species were evaluated as ethene oligomerization catalysts after activation with MAO. All complexes were highly active, with TOFs between 24 × 10 3 and 85 × 10 3 (mol C 2 H 4 ) • (mol Ni • h) -1 . Butenes were the major product in all cases, forming 76 to 96 mol % of the product. Selectivities for 1-butene were between 10% and 40%. The cationic palladium species showed a very low productivity for ethene oligomerization, with TOFs e16 (mol C 2 H 4 ) • (mol Pd • h) -1 and 38 to 88 mol % butenes as the main product.

TroVacene (1) was prepared by two noVel procedures, employing readily aVailable Vanadium precursors and after dimetalation conVerted into the [2]boratroVacenophane 2 and the [1]boratroVacenophane 4. The reactiVity of the boronboron bond in 2 toward [Pt(PEt 3 ) 4 ] was studied and afforded the oxidatiVe addition product 3. X-ray crystallographic studies on 2-4 reVealed mutual tiltings of the carbocyclic rings of 11.4, 4.98, and 28.23°, respectiVely.

Chromsandwich mit „Henkel“: Ein [2]Boratrochrocenophan mit Dibor‐Brücke (Schema links) wurde synthetisiert und an [Pt(PEt3)4] oxidativ addiert. Das so erhaltene [3]Boraplatinatrochrocenophan, das erste Beispiel eines ansa‐[3]Boraplatina‐Sandwichkomplexes, wurde in Lösung und im Kristall charakterisiert.