Birte Ahrens

Synthesis, characterisation and optical spectroscopy of diynes and poly-ynes containing derivatised fluorenes in the backbone

A series of trimethylsilyl-protected and terminal mono- and bis-alkynes based on 9,9-dioctylfluorene, 2-(trimethylsilylethynyl)-9,9-dioctylfluorene 1a, 2-ethynyl-9,9-dioctylfluorene 1b, 2,7-bis(trimethylsilylethynyl)-9,9-dioctylfluorene 2a, 2,7-bis(ethynyl)-9,9-dioctylfluorene 2b, have been synthesised. Reaction of trans-[(PnBu3)2PtCl2] with 2 equivalents of the terminal ethyne 1b yields the mononuclear platinum(II) diyne 3, reaction of trans-[(Ph)(Et3P)2PtCl] with 0.5 equivalents of the diterminal ethyne 2b gives the dinuclear platinum(II) diyne 4 while 1 ∶ 1 reaction between trans-[(PnBu3)2PtCl2] and 2b gives the platinum(II) poly-yne 5. Treatment of 2,5-dioctyloxy-1,4-diiodobenzene with 1b in 1 ∶ 2 stoichiometry produces the organic di-yne 6 while 1 ∶ 1 reaction between 2,5-dioctyloxy-1,4-diiodobenzene and 2b, 2,7-bis(ethynyl)fluorene or 2,7-bis(ethynyl)fluoren-9-one produces the organic co-poly-ynes 7–9. All the new materials have been characterised by analytical and spectroscopic methods and the single crystal X-ray structures of 2a and 3 have been determined. The diynes and poly-ynes are soluble in organic solvents and are readily cast into thin films. Optical spectroscopic measurements reveal that the attachment of octyl side-chains on the fluorenyl spacer reduces inter-chain interaction in the poly-ynes while a fluorenonyl spacer creates a donor–acceptor interaction along the rigid backbone of the organometallic poly-ynes and organic co-poly-ynes.

Synthesis, characterisation and optical spectroscopy of platinum(II) di-ynes and poly-ynes incorporating condensed aromatic spacers in the backbone

A series of protected and terminal dialkynes with extended pi-conjugation through a condensed aromatic linker unit in the backbone, 1,4-bis(trimethylsilylethynyl)naphthalene, 1,4-bis(ethynyl)naphthalene, 9,10-bis(trimethylsilylethynyl)anthracene, 9,10-bis(ethynyl)anthracene, have been synthesized and characterized spectroscopically. The solid-state structures of and have been confirmed by single crystal X-ray diffraction studies. Reaction of two equivalents of the complex trans-[Ph(Et(3)P)(2)PtCl] with an equivalent of the terminal dialkynes 1,4-bis(ethynyl)benzene and, in (i)Pr(2)NH-CH(2)Cl(2), in the presence of CuI, at room temperature, afforded the platinum(II) di-ynes trans-[Ph(Et(3)P)(2)Pt-C[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-Pt(PEt(3))(2)Ph](R = benzene-1,4-diyl; naphthalene-1,4-diyl and anthracene-9,10-diyl ) while reactions between equimolar quantities of trans-[((n)Bu(3)P)(2)PtCl(2)] and under similar conditions readily afforded the platinum(II) poly-ynes trans-[-((n)Bu(3)P)(2)Pt-C[triple bond]C-R-C[triple bond]C-](n)(R = naphthalene-1,4-diyl and anthracene-9,10-diyl ). The Pt(II) diynes and poly-ynes have been characterized by analytical and spectroscopic methods, and the single crystal X-ray structures of and have been determined. These structures confirm the trans-square planar geometry at the platinum centres and the linear nature of the molecules. The di-ynes and poly-ynes are soluble in organic solvents and readily cast into thin films. Optical spectroscopic measurements reveal that the electron-rich naphthalene and anthracene spacers create strong donor-acceptor interactions between the Pt(II) centres and conjugated ligands along the rigid backbone of the organometallic polymers. Thermogravimetry shows that the di-ynes possess a somewhat higher thermal stability than the corresponding poly-ynes. Both the Pt(II) di-ynes and the poly-ynes exhibit increasing thermal stability along the series of spacers from phenylene through naphthalene to anthracene.

Hydrogen bonding and halogen–halogen interactions in 4-halopyridinium halides

The solid state structures of the 4-halopyridinium halides 4-XC5H4NH+X- (X=Cl, Br, I) all display chains of the form [···X–C5H4N–H+···X-···X–C5H4N–H+···X-···] involving N–H···X- hydrogen bonds and X···X- contacts; the former become longer and the latter shorter (relative to the sum of the van der Waals radii) with increasing size of X.

Synthesis and characterisation of new acetylide-functionalised aromatic and hetero-aromatic ligands and their dinuclear platinum complexes

A new series of rigid rod protected and terminal dialkynes with extended π-conjugation through aromatic and hetero-aromatic linker units in the backbone, 2,5-bis(trimethylsilylethynyl)-1-(2-ethylhexyloxy)-4-methoxybenzene 1a, 2,5-bis(ethynyl)-1-(2-ethylhexyloxy)-4-methoxybenzene 1b, 5,8-bis(trimethylsilylethynyl)quinoline 2a, 5,8-bis(ethynyl)quinoline 2b, 2,3-diphenyl-5,8-bis(trimethylsilylethynyl)quinoxaline 3a, 2,3-diphenyl-5,8-bis(ethynyl)quinoxaline 3b, 4,7-bis(trimethysilylethynyl)-2,1,3-benzothiadiazole 4a and 4,7-bis(ethynyl)-2,1,3-benzothiadiazole 4b, has been synthesised. Treatment of the complex trans-[Pt(Ph)(Cl)(Et3P)2] with half an equivalent of the diterminal alkynes 1b–4b in iPr2NH–CH2Cl2, in the presence of CuI, at room temperature, afforded the platinum(II) di-yne complexes trans-[(Et3P)2(Ph)Pt–CC–R–CC–Pt(Ph)(Et3P)2] [R = 1-(2-ethylhexyloxy)-4-methoxybenzene-2,5-diyl 1c, quninoline-5,8-diyl 2c, 2,3-diphenylquinoxaline-5,8-diyl 3c, 2,1,3-benzothiadiazole-4,7-diyl 4c] in good yields. The new acetylide-functionalised ligands and the platinum(II) σ-acetylide complexes have been characterised by analytical and spectroscopic methods and X-ray single crystal structure determinations for 2c–4c. The absorption spectra of the complexes 2c–4c show substantial donor–acceptor interaction between the platinum(II) centres and the conjugated ligands. The photoluminescence spectra of 1c–3c show characteristic singlet (S1) and triplet (T1) emissions. Both the singlet and triplet emissions as well as the absorption decrease in energy with increasing electronegativity of the spacer groups along the series 1c–4c.

Transition Metal Complexes in Organic Synthesis. Part 57: Synthesis of 1-Azabuta-1,3-dienes and Application to Catalytic Complexation of Buta-1,3-dienes and Cycloalkadienes by the Tricarbonyliron Fragment

The 1-azabuta-1,3-dienes 5a – g were prepared and transformed to the corresponding tricarbonyliron complexes 6 . The efficiency of 6 as tricarbonyliron transfer reagents and the activity of 5a – g for the catalytic complexation with either nonacarbonyldiiron or pentacarbonyliron was investigated. It was shown that the catalytic complexation with pentacarbonyliron using the azadiene 5b as catalyst in dioxane at reflux can be applied to 1-methoxycyclohexa-1,4-diene.

Hydrogen Bonding Networks in Bis(amine)gold(I) Complexes with Disulfonylamide Anions

The use of disulfonylamines as counter-ions allows the synthesis of stable ionic gold(I) complexes with the amine ligands cyclohexylamine, benzylamine, 3-iodobenzylamine, morpholine, pyrrolidine, and piperidine. There is a considerable increase in stability for the morpholine complex compared to the previously synthesised chloro derivative; the benzylamine derivatives displayed better solubility and crystallinity than their chloro analogues. The use of silver disulfonylamine derivatives in the syntheses led in two cases to the incorporation of silver into the products, with concomitantly poor yields. Crystal structure determinations of eight complexes revealed, as expected, extensive systems of N−H···O hydrogen bonds. Amines with NH functions tend to form hydrogen-bonded chain motifs, those with NH2 as donor group form layers of linked ring patterns. It thus seems that the packing can more easily be classified in terms of influence of the cation than of the anion. Some C−H···O hydrogen bonds were also observed, but play a less important role. Aurophilic contacts were not observed, although one mixed gold/silver complex displayed short Au···Ag contacts. Of the two compounds containing iodine, only one showed short I···I contacts.

The Role of N–H···Cl Hydrogen Bonds in Gold(I) Complexes with Aliphatic Amine Ligands

Various gold(I) complexes of aliphatic amines have been prepared by the reaction of chloro(tetrahydrothiophene)gold(I) with the respective amines. The stability of these complexes can be attributed partly to the formation of hydrogen bonds involving the N–H functions, and partly to aurophilic interactions. Analysis of these secondary contacts suggests an inverse correlation between lengths of aurophilic interactions and hydrogen bonds.

Structural characterisation of a series of acetylide-functionalised oligopyridines and the synthesis, characterisation and optical spectroscopy of platinum di-ynes and poly-ynes containing oligopyridyl linker groups in the backbone

A series of trimethylsilyl-protected bis(ethynyl)oligopyridine derivatives Me3SiCC–R–CC–SiMe3 (R = 2,2′-bipyridine-5,5′-diyl (1a), 2,2′-bipyridine-6,6′-diyl (2a), 2,2′:6′,2″-terpyridine-6,6″-diyl (3a), 4′-phenyl-2,2′:6′,2″-terpyridine-6,6″-diyl (4a)) has been synthesised and 2a–4a have been characterised by single crystal X-ray crystallography. The corresponding terminal di-ynes H–CC–R–CCH (1b–4b) and their dinuclear platinum(II) complexes trans-[(Et3P)2(Ph)Pt–CC–R–CC–Pt(Ph)(Et3P)2] (1M–4M) have been characterised spectroscopically and by single-crystal X-ray crystallography for 2M. Novel platinum(II) poly-yne polymers trans-[Pt(PBun3)2–CC–R–CC–]n (1P–4P) containing the oligopyridyl linker groups in the backbone have been synthesised by the CuI-catalysed dehydrohalogenation polycondensation reaction of 1b–4b and trans-[(Bu3P)2PtCl2] in Pri2NH–CH2Cl2. The polymeric materials exhibit decreasing thermal stability with increasing number of pyridine units in the linker group. In the absorption and phosphorescence spectra, the platinum(II) poly-yne and di-yne complexes 1P, 1M show red shifts whereas the complexes 2P–3P, 2M–3M show blue shifts of the S1 and T1 states. At room temperature, the phosphoresence spectra indicate some excimer formation whereas at 10 K, only intra-chain emission occurs. The results of the photophysical studies are compared with those obtained for other platinum(II)-containing poly-ynes and related organometallic polymers.

Gold(I) complexes with amine ligands. 3 Competition between auriophilic and hydrogen bonding interactions in dimeric species

The gold(I) complexes (pip)2Au+Cl- and (Cy2NH)AuCl (pip=piperidine, Cy=cyclohexyl) crystallise as loose dimers; in the ionic species N–H···Cl- hydrogen bonding is the main secondary interaction, whereas in the neutral complex the N–H···Cl hydrogen bonding is weaker but is compensated by an auriophilic interaction.

Gold(I)-Komplexe mit Aminliganden, II. (Methylpyridin)-Komplexe von Gold(I) Gold(I) / Complexes with Amine Ligands, II. Methylpyridine Complexes of Gold(I)

Abstract Gold(I) complexes of overall formula LAuCl (L = various methylpyridines) are non-conducting in acetone. X-ray structure analyses show that the solid state structure of the cor responding complex 1 (L = 2-picoline) is molecular; the 3-picoline derivative 2 is however ionic (L2Au)+(AuCl2)-. 3-Picoline forms a molecular complex LAuC6F5 (3) and also the ionic (L2Au)+(SbF6)- (4). Complexes 1, 2 and 4 display short Au ··· Au contacts, leading to chains of gold atoms; additionally, complexes 3 and 4 show weak Au ··· F contacts. The (3-picoline)-gold(III) complex trans-(L2AuCl2)+(SbF6)- (5) was obtained as a by-product; it too contains short Au ··· F contacts.