Search

Iminosulfane(phosphane)carbon(0) derivatives (iSPCs; Ar3P→C←SPh2(NMe); Ar=Ph ( 1), 4-MeOC6H4 ( 2), 4-(Me2N)C6H4 ( 3)) have been successfully synthesized and the molecular structure of 3 characterized. Carbone 3 is the first thermally and hydrolytically stable carbone stabilized by phosphorus and sulfur ligands. DFT calculations reveal the electronic structures of 1- 3, which have two lone pairs of electrons at the carbon center. First and second proton affinity values are theoretically calculated to be in the range of 286.8-301.1 and 189.6-208.3 kcal mol−1, respectively. Cyclic voltammetry measurements reveal that the HOMO energy levels follow the order of 3> 2> 1 and the HOMO of 3 is at a higher energy than those of bis(chalcogenane)carbon(0) (BChCs). The reactivities of these lone pairs of electrons are demonstrated by the C-diaurated and C-proton-aurated complexes. These results are the first experimental evidence of phosphorus- and sulfur-stabilized carbones behaving as four-electron donors. In addition, the reaction of hydrochloric salts of the carbones with Ag2O gives the corresponding AgI complexes. The resulting silver(I) carbone complexes can be used as carbone transfer agents. This synthetic protocol can also be used for moisture-sensitive carbone species. [ABSTRACT FROM AUTHOR]

Electronic effects on the central carbon atom of carbone, generated by the replacement of the SIV ligand of carbodisulfane (CDS) with other chalcogen ligands (Ph2E, E=S or Se), were investigated. The carbones Ph2E→C←SPh2(NMe) [E=S( 1) or Se( 2)] were synthesized from the corresponding salts, and their molecular structures and electronic properties were characterized. The carbone 2 is the first carbone containing selenium as the coordinated atom. DFT calculations revealed the electronic structures of 1 and 2, which have two lone pairs of electrons at the carbon center. The trend in HOMO energy levels, estimated by cyclic voltammetry measurements, for the carbones and CDS follows the order of 2> 1>CDS. Analysis of a doubly protonated dication and trication complex revealed that the central carbon atom of 2 behaves as a four-electron donor. [ABSTRACT FROM AUTHOR]

A newly designed electron donor-acceptor conjugate consisting of an endohedral dimetallofullerene (La2@ Ih-C80) and phenoxazine (POZ) was successfully synthesized under Prato conditions. Our results document that the 1,3-dipolar cycloaddition took place across the [5,6] junction to afford exclusively the corresponding [5,6] cycloadduct. The structure of the conjugate was characterized by means of NMR spectroscopy, absorption spectroscopy, and electrochemical studies. Computational calculations suggest that the electron density of the highest occupied molecular orbital (HOMO) is distributed on the POZ moiety, whereas that of the lowest unoccupied molecular orbital (LUMO) is located at the endohedral La atoms, leading to efficient separation of the HOMO and LUMO in the conjugate. Time-resolved absorption spectroscopic investigations and spectroelectrochemical measurements corroborate the formation of the energetically low-lying (La2@ Ih-C80).−-(POZ).+ radical-ion-pair state by means of ultrafast through-space electron transfer. [ABSTRACT FROM AUTHOR]

Bis(sulfane)carbon(0) (BSC; Ph2S→C←SPh2 ( 1)) is successfully synthesized by deprotonation of the corresponding protonated salt 1⋅HTfO. The diprotonated salt 1⋅(HTfO)2 as the starting material can be also easily accessed by the deimination of iminosulfane(sulfane)carbon(0) (iSSC) ⋅HBF4. Density functional theory calculations revealed the peculiar electronic structure of 1, which has two lone pairs of electrons at the central carbon atom. The largest proton affinities (PA(1): 297.5 kcal mol−1; PA(2): 183.7 kcal mol−1) and the highest energy levels of the HOMOs (HOMO: −4.89 eV; HOMO−1: −5.02 eV) for 1 among the two-sulfur-stabilized carbones clearly indicate the strong donor ability of carbon center stabilized by two SII ligands. The donating ability of these lone pairs of electrons is demonstrated by the C-diaurated and C-proton-aurated complexes, which provide the first experimental evidence for two-sulfurstabilized carbones behaving as four-electron donors. Furthermore, the syntheses and application of AgI carbone complexes as carbone transfer agents are also reported. [ABSTRACT FROM AUTHOR]

The cover page of the 2014 issue of the journal "Angewandte Chemie," International Edition is presented.

The cover picture shows the molecular structure of a La2@Ih‐C80–phenoxazine conjugate and its differential absorption spectra observed upon femtosecond flash photolysis in tetrahydrofuran. Spectroscopic investigations corroborate the formation of the energetically low‐lying radical‐ion‐pair‐state by means of ultrafast through‐space electron transfer. Details are given in the Full Paper by Takeshi Akasaka, Dirk M. Guldi and co‐workers on page 1067 in Issue 7, 2017 (DOI: 10.1002/cplu.201600391). [ABSTRACT FROM AUTHOR]

Two‐sulfur‐stabilized carbones: the presence of a “second” lone pair on a coordinated atom significantly enhances the electron‐donating ability of the central carbon in carbones. The strongest electron‐donating ability of bis(sulfane)carbon(0) (BSC) among the two‐sulfur‐stabilized carbones was demonstrated by the generation of diprotonated salt BSC⋅H2+. The C‐digold(I) complexes of two‐sulfur‐stabilized carbones provide the first experimental proof of their four‐electron‐donating ability. More information can be found in the Full Paper by T. Fujii et al. on page 8694. [ABSTRACT FROM AUTHOR]