Diarylboron diketonates were successfully prepared by the reaction of 1,3-diketone derivatives and arylboron compounds such as triphenylborane [BPh3] and fluorobis(pentafluorophenyl)borane diethyl etherate [(C6F5)2BF x OEt2]. The fluorescent emission of their complexes took place depending on the substituent of the arylboron moiety. In particular, a boron 1,3-bis(4-methoxyphenyl)-1,3-diketonate chelated by a strong electron-withdrawing C6F5 group exhibited the most intense fluorescence.

No abstract

Novel 1,4-diarsa-2,5-cyclohexadiene, i.e., 1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(tert-butoxycarbonyl)-1,4-diarsinine, was synthesized by radical reaction of pentamethylcyclopentaarsine (cyclo-(MeAs) 5 ) and di-tert-butyl acetylenedicarboxylate. Two steroisomers, cis-DHDAtBu and trans-DHDAtBu, were obtained as crystals, of which structures were determined by X-ray crystallography. The six-membered ring in cis-DHDAtBu has a boat form, and both the methyl groups on the arsenic atoms are in equatorial positions. Two different polymorphs of trans-DHDAtBu were obtained as a pale yellow platelet crystal and a colorless crystalline fiber. The colorless crystal has a boat-shaped sixmembered ring, and the yellow crystal has a nearly flat chair-shaped ring. The double bonds connected with the two arsenic atoms were longer than that of the boat-shaped DHDAtBu. The UV-vis absorption spectra of cis-DHDAtBu and trans-DHDAtBu in CH 2 Cl 2 showed long-wavelength absorption maxima at 272 and 300 nm, respectively.

Mono- and dinuclear trans-dichloroplatinum(II) complexes, i.e., trans-PtCl2(cis-DHDAtBu)2 and trans,trans-Pt2Cl4(cis-DHDAtBu)2, respectively, using cis-1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(tert-butoxycarbonyl)-1,4-diarsinine (cis-DHDAtBu), which was prepared by the radical reaction of pentamethylcyclopentaarsine (cyclo-(MeAs)5) and di-tert-butyl acetylenedicarboxylate, were obtained individually as only products by stoichiometric addition of cis-bis(benzonitrile)dichloroplatinum to cis-DHDAtBu. Replacement of chloride with iodide by adding KI into acetone solutions of trans-PtCl2(cis-DHDAtBu)2 and trans,trans-Pt2Cl4(cis-DHDAtBu)2 gave trans-PtI2(cis-DHDAtBu)2 and trans,trans-Pt2I4(cis-DHDAtBu)2, respectively. The structures of all the obtained compounds were confirmed by 1H and 13C NMR spectra, X-ray crystallography, and elemental analysis. The interior angles around the arsenic and the As−CC bond angle were significantly varied in a series of the present platinum(II) complexes. These observations suggest that the flexibility of the bond angles around the arsenic center is an inherent property in the present organoarsenic compounds. The intermetallic interaction was induced in the dinuclear platinum(II) “face-to-face” complex using cis-DHDAtBu by the replacement of chloride with iodide. The distance of the Pt−Pt of trans,trans-Pt2I4(cis-DHDAtBu)2 was shortened compared with that of trans,trans-Pt2Cl4(cis-DHDAtBu)2, and the new broad absorption band at around 562 nm was observed in the solution of trans,trans-Pt2I4(cis-DHDAtBu)2. Density functional theory calculations indicate that the frontier molecular orbitals in trans,trans-Pt2Cl4(cis-DHDAOH)2, in which H atom surrogates were used in place of the tBu group, show no d−d interaction orbitals. On the other hand, the HOMO level in trans,trans-Pt2I4(cis-DHDAOH)2 has mainly d xz contributions in the π*-antibonding MO.

New through-space conjugated polymers comprising the pseudo-ortho-linked [2.2]paracyclophane moiety were synthesized by the Sonogashira coupling reaction. All the synthesized polymers were soluble in common organic solvents and could form thin films. The UV-vis absorption spectra of the synthesized polymers revealed an extension of the conjugation length owing to the through-space interactions. The polymers exhibited a blue-light emission in both solution and film states.