Jason G. M. Morton

Trans-spanning acetylenic bispyridine ligands: synthesis and structural characterization of novel organic and organometallic pseudodehydroannulenes

Abstract The synthesis of a novel ferrocene based pincer ligand C5H5-Fe[C5H3(--C5H4N)2] is reported. This pincer ligand was prepared by the Pd-catalyzed reaction of 1,2-diethynylferrocene with 2-iodopyridine. The complex is a trans-spanning ligand and analogous to 1,2-bis(2-pyridinylethynyl)-4,5-dimethoxybenzene. A series of trans-coordinated 1:1 or 2:1 complexes (empirical formulae C51H37ClCuF3N4O7S and C23H18Cl4N2O2Pd) that form from the ligands and (CH3CN)2PdCl2 or Cu(OTf)2 were obtained. These complexes form 13-membered rings. Structurally these complexes resemble a hexadehydro[14]annulene in which two benzene groups are replaced by pyridine rings and one alkyne group is replaced by the co-ordinated metal. All of the trans-spanning complexes were characterized by single crystal X-ray diffraction. Their molecular and solid-state structures are discussed. The Pd-complexes are of interest as potential high activity catalysts for Sonogashira-type couplings of alkynes to aryl halides. The 1,2-(bis-2′-pyridylethyn-1′-yl)ferrocene, was crystallized with PdCl2 to obtain a novel organometallic trans-spanning complex of the formula C24H16Cl2FeN2Pd that was crystallographically characterized.

Synthesis and Structural Characterization of Organometallic Cyclynes: Novel Nanoscale, Carbon‐Rich Topologies

A combination of Pd- and Cu-catalyzed couplings make the ferrocene and cyclobutadiene(cyclopentadienylcobalt)-based halfwheels and the cyclobutadiene(cyclopentadienylcobalt)-based seco-wheel accessible. These targets can formally be constructed by fusing two or three organometallic benzohexadehydro[14]annulenes along an alkyne unit. In addition, a ferrocene-based, enlarged version of the half wheel was prepared. This target compound is obtained by formally fusing two organometallic benzododecadehydro[18]annulenes. Single crystal structures of three target molecules, the cyclobutadiene complex C51H37Co, the ferrocene derivativ eC 51H36Fe, and the cyclobutadiene complex C69H59Co were performed to verify the proposed geometries. # 2003 Published by Elsevier Science B.V.

Synthesis and structural characterization of organometallic cyclynes: novel nanoscale, carbon-rich topologies

A combination of Pd- and Cu-catalyzed couplings make the ferrocene and cyclobutadiene(cyclopentadienylcobalt)-based half-wheels and the cyclobutadiene(cyclopentadienylcobalt)-based seco-wheel accessible. These targets canformally be constructed by fusing two or three organometallic benzohexadehydro[l4]annulenes along an alkyne unit. In addition, a ferrocene-based, enlarged version of the half wheel was prepared. This target compound is obtained by formally fusing two organometallic benzododecadehydro[18]annulenes. Single crystal structures of three target molecules, the cyclobutadiene complex C 1 5 H 1 7 Co, the ferrocene derivative C 1 5 H 3 6 Fe, and the cyclobutadiene complex C 6 9 H 5 9 Co were performed to verify the proposed geometries.

A simple route to (tetraethynylcyclobutadiene)cyclopentadienylcobalt

Abstract Reaction of 2-(trimethylsilylethynyl)-1,3-dioxane with CpCo(CO)2 followed by reaction with Me4NF in and NaH furnishes 1,2- and [1,3-bis[2-dioxanyl]cyclobutadienecyclopentadienylcobalt in an overall combined yield of 95% in a 3.5:1 ratio. Metalation of the 1,2-complex or the 1,3-complex by BuLi is followed by formylation. Transformation of the resulting aldehyde into an alkyne by CH3CO(CN2)PO(OEt)2 and repetition of the reaction sequence furnishes the 1,2-diethynyl- or [1,3-diethynyl(2-dioxanyl)cyclobutadiene]cyclopentadienylcobalt. Deketalization and subsequent Ohira reaction transforms these precursors into a host of different tetraethynylated CpCo-stabilized cyclobutadienes. The synthetic method is solution-phase based and circumvents the cumbersome flash-vacuum pyrolysis step hitherto necessary for the preparation of tetraethynylated CpCo-stabilized cyclobutadiene complexes.

Butterfly topologies: new expanded carbon-rich organometallic scaffolds

Starting from either (tetraethynylcyclobutadiene)cyclopentadienylcobalt or [1,2-diethynyl-3,4-(2-dioxanyl)cyclobutadiene]cyclopentadienylcobalt a sequence of copper and Pd-catalyzed couplings of the Eglinton and the Heck � /Cassar � /Sonogashira � / Hagihara type furnishes five bow-tie shaped doubly annelated dehydroannulenes, the largest of which featuring a (formal) 7,8:13,14:25,26:31,32-tetra(4?alkyl-1?,2?-benzo)tricyclo[18,16,0 2,19 ]hexatricosa-3,5,9,11,15,17,21,23,27,29,33,35-dodecayne1,7,13,19,25,31-hexaene hydrocarbon ligand with a cyclopentadienyl-cobalt stabilized cyclobutadiene complex as its central unit. Single crystal X-ray structures of two of the smaller butterflies are reported and their surprising solid-state packing is discussed herein. # 2003 Published by Elsevier Science B.V.

A supramolecular organometallic?metalorganic squareElectronic supplementary information (ESI) available: experimental, including details of preparation and spectroscopic data for 2?6. See http://www.rsc.org/suppdata/cc/b3/b304169g/

Synthesis and structural characterization of [tetrakis(2-pyrimidinylethynyl)cyclobutadiene][(cyclopentadienyl)cobalt] and its mercury(II)chloride complex are reported; in the complex, the mercury is in an unusual square planar coordination environment.

A solution-phase route to a tetraethynylated (cyclobutadiene)cyclopentadienylcobalt complex with a para-(1,3,2,4)-substitution pattern

The synthesis of a tetraethynylated, CpCo-stabilized cyclobutadiene complex via a metalation/carbonylation/alkynylation route is reported; this synthetic sequence allows, for the first time, the solution phase synthesis of a tetraethynylcyclobutadiene(cyclopentadienyl)cobalt derivative, and sorts the four alkyne substituents into two para-related groups.