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The synthesis and characterization of a new paramagnetic ligand, 4-(N′-methyl-2′-benzimidazolyl)-1,2,3,5-dithiadiazolyl (MebimDTDA), is presented. MebimDTDA exhibits polymorphism in the solid state. The red microcrystalline form (Form I-red) is diamagnetic below T = 370 K, consistent with typical multi-center two-electron bonding interactions (i.e., pancake bonds) between planar π-radicals. By contrast, the green–black crystalline form (Form II-green) exhibits paramagnetic properties consistent with the observed unusual crystal packing in which some, but not all, of the radicals are arranged in a typical pancake-bonded geometry. Crystallographic analysis, magnetic data, and computational methods are employed to elucidate the structure-property relationship, with an emphasis on the role of crystal packing. [ABSTRACT FROM AUTHOR]

The synthesis and isolation of [Ru(Cp)(PCy2NPh2)(=C=CHPh]PF6 and [Ru(Cp*)(PCy2NCy2)(=C=CHPh)]PF6 was successfully accomplished. Use of these ruthenium vinylidene complexes for stoichiometric reactions with a variety of amines was performed. Upon reaction with alkyl amines, deprotonation of the Cβ hydrogen resulted in formation of acetylide complex [Ru(Cp*)(PCy2NPh2)(−C≡CPh)], and the species was confirmed through independent synthesis. In contrast, reaction of the less basic aryl amine aniline with [Ru(Cp)(PCy2NCy2)(=C=CHPh)]PF6 resulted in outer sphere addition to give a Fischer carbene product. [ABSTRACT FROM AUTHOR]

Boraadamantanes are a privileged class of caged group 13 compounds having a trigonal pyramidal (non-VSEPR) ground-state. The Lewis acid–base chemistry of this type of compound is underdeveloped when compared to acyclic derivatives. This report provides the first examples of bifunctional boraadamantanes with an appended phosphine moiety (also the first boraadamantanes having a phosphorus–boron bond). Using this scaffold, boraadamantane coordination compounds are accessed for the first time. [ABSTRACT FROM AUTHOR]

Since the development of the chemistry and applications of boron dipyrromethene dyes (BODIPYs), numerous other platforms based on boron complexes of N‐donor ligands have emerged as molecular optoelectronic materials. By tailoring the structure of the ligand bound to boron, the optical and electronic properties of a compound can be precisely tuned for unique properties, such as aggregation‐induced emission (AIE) in the case of boron difluoride hydrazones (BODIHYs). We examine the impact of modifying the typical bidentate hydrazone ligand structure used to prepare BODIHYs to enable a tridentate coordination mode to produce boron complexes of tridentate acyl pyridylhydrazones. This change allows for the use of arylboronic acids as sources of boron and facilitates the inclusion of complex organic components at the boron centre, including the formation of dye‐dye conjugates. The synthesized compounds exhibit distinct optical and electronic properties when compared to BODIHYs, such as reversible electrochemical reduction and up to a >300 nm pseudo‐Stokes shift in the solid state, all of which were supported by density functional theory calculations. [ABSTRACT FROM AUTHOR]

Heterocycles that pair main group elements and nitrogen are extremely important within the π‐conjugated heterocycles research community. Compared to the vast number of boron‐nitrogen heterocycles, those that include phosphorus are less common. Furthermore, the use of phosphorus‐nitrogen triple bonds of any type to prepare such compounds is unprecedented. Here, we pair pyridyl hydrazonide ligands with phosphadiazonium cations and demonstrate that the chelated Mes*NP group is directly implicated in the photophysical and redox properties observed for the resulting heterocycles. In doing so, we introduce a novel building block for the production of phosphorus‐containing heterocycles that could find use in small molecule activation and catalysis or as the functional component of emerging organic electronics. [ABSTRACT FROM AUTHOR]

Zwitterionic dicoordinate phosphorus(I) compounds (1 and 2), formally a charge neutral triphosphenium ion or phosphanide, are shown to coordinate to a variety of late transition metals. The reaction of the phosphanide proligands with [{Rh(COD)Cl}.sub.2] results in an equilibrium process that varies as a function of temperature or reaction stoichiometry. Palladium(II) compounds have a tendency to chlorinate the borate backbone while giving dimeric coordination compounds (1Pd) and also a decomposition product (3) where the P(I) atom was replaced. Both 'lone pairs' of electrons on phosphorus are utilized simultaneously in the dominant product from the reaction of 1 and [[Pt[Me.sub.2](pμS[Me.sub.2])].sub.2], while each platinum center ortho-metallated a phenyl substituent on the flanking phosphorus atoms (1Pt). Stable, isolable, and fully characterized dimeric mercury complexes (1Hg and 2Hg) are produced nearly quantitatively from the reaction of the phosphanide proligand with Hg[Cl.sub.2]. All compounds described were structurally characterized using single crystal X-ray diffraction and represent a growing series of zwitterionic P(I) coordination compounds that cannot be isolated when a cationic triphosphenium ion is used. Key words: phosphorus, zwitterions, coordination chemistry, main group chemistry. Resume: Les composes zwitterioniques bis-coordonnes de phosphore(I) (1 et 2), qui sont en fait des ions triphosphenium neutres ou des phosphanures, se sont reveles capables de se coordonner a divers metaux de transition de fin de serie. La reaction des proligands phosphanures avec le complexe [[Rh(COD)Cl].sub.2] entraine un processus d'equilibre qui varie en fonction de la temperature ou de la strechiometrie de la reaction. Les composes de palladium(II) ont tendance a chlorer la chaine principale boratee et a donner, pour leur part, les composes de coordination dimeriques (1Pd) ainsi que le produit de decomposition (3) dans lequel l'atome de P(I) a ete remplace. Les deux doublets non liants des electrons du phosphore sont engages simultanement dans le produit majoritaire provenant de la reaction entre le compose 1 et le complexe [[Pt[Me.sub.2](μ-S[Me.sub.2])].sub.2]. Quant aux noyaux de platine, chacun d'eux s'est insere en position ortho de l'un des substituants phenyles de l'atome de phosphore voisin (1Pt). Des complexes dimeriques de mercure (1Hg et 2Hg) stables, isolables et entierement caracterises sont produits de facon quasi quantitative par la reaction du proligand phosphanure avec le Hg[Cl.sub.2]. Tous les composes decrits ont ete structurellement caracterises par diffraction des rayons X d'un cristal unique et representent une serie en expansion de composes zwitterioniques de coordination P(I) ne pouvant pas etre isoles lorsqu'un cation triphosphenium est utilise. [Traduit par la Redaction] Mots-cles: phosphore, zwitterions, chimie de coordination, chimie des elements du groupe principal., Introduction Tertiary phosphines and N-heterocyclic carbenes are ubiquitous two-electron donor ligands that have been shown to form stable coordination compounds to essentially every transition metal or main group element spanning [...]

The new, unsymmetrical azobenzene-tagged ligand 4-(4-azobenzene)-3,6-di(2-pyridyl)pyridazine, adpp, forms complexes with platinum(II) and platinum(IV), which exist as a mixture of geometrical isomers. The complexes are characterized primarily by their NMR spectra, while the structures of the ligand and its complexes [Pt[Me.sub.2](adpp)], [PtBr[Me.sub.2](C[H.sub.2][C.sub.6][H.sub.4]-4-t-Bu)(adpp)], and [PtBr[Me.sub.2](C[H.sub.2][C.sub.6][H.sub.3]-3,5-t-[Bu.sub.2])(adpp)] have been structurally characterized. In solution, the compounds undergo easy photochemical trans-cis switching of the azobenzene group, with subsequent slow thermal isomerization back to the more stable trans-azobenzene isomer. Key words: platinum, azobenzene, photochemistry, organometallic. Le nouveau ligand marque par l'azobenzene, la 4-(4-azobenzene)-3,6-di(2-pyridyl)pyridazine, ou adpp, forme des complexes avec le platine(II) et le platine(IV), presents sous forme d'un melange d'isomeres geometriques. Les complexes sont< principalement caracterises a l'aide de leur spectre RMN et le ligand et ses complexes, [Pt[Me.sub.2](adpp)], [PtBr[Me.sub.2](C[H.sub.2][C.sub.6][H.sub.4]-4-t-Bu)(adpp)| et [PtBr[Me.sub.2](C[H.sub.2][C.sub.6][H.sub.3]-3,5-t-[Bu.sub.2])(adpp)| par leur structure chimique. En solution, les composes subissent facilement une transposition photochimique trans-cis du groupe azobenzene, qui redevient, par isomerisation thermique lente, l'isomere transazobenzene, plus stable. [Traduit par la Redaction] Mots-cles : platine, azobenzene, photochimie, organometallique., Introduction There is continuing interest in the use of azobenzene derivatives in artificial photochromic systems because the azobenzene unit can be switched reversibly between trans and cis isomers, which have [...]

The preparation and characterization of a series of functionalized radical anion semiquinone (SQ-Ar) ligands and their [Mn.sup.II]- and [Cu.sub.II]hydro-tris(3-cumenyl-5-methylpyrazolyl)borate complexes are reported. The results show that mesomeric substituents, Ar, would decrease the ferromagnetic contribution via direct exchange to the [M.sup.II]-SQ exchange parameters (J) for LCu(SQ-Ar) but in a series of SQ-Ar ligands, a more-withdrawing Ar would have a more ferromagnetic.

The synthesis and characterization of a series of [Cu.sub.1] methyl, phenyl, anilido, ethoxide, and phenoxide complexes with the NHC ligands IPr, IMes [IMes = 1,3-bis(2,4,6-trimethylphenyl)imidiazol-2-ylidene], and SIPr [SIPr = 1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] are discussed. Details of characterization, solid-state structures, comparative relevant to the observed reactivity are provided.