Transmetalation reactions of ArLi with ECl 3 (E = Al, P, In, Bi) and ArSnBu 3 with ECl 3 (E = B, Ga, Tl, As, Sb) gave rise to the formation of peri-substituted diphenylphosphinoacenaphthyl−element dichlorides ArECl 2 (Ar = 6-Ph 2 PAce-5-), which were characterized by multinuclear NMR spectroscopy and X-ray crystallography. DFT calculations were performed on the compounds at relaxed gas-phase molecular geometries. For the series ArECl 2 containing group 13 elements one structure type featuring regular Lewis pairs with short E−P peri distances (E = B, Al, Ga, In, Tl) was observed. For the series ArECl 2 containing group 15 elements two structural types with very different peri distances (E = P, As, Sb, Bi) were found. The computed electron and pair densities were topologically analyzed according to the atoms-in-molecules (AIM) and electron localizability indicator (ELI-D) spacepartitioning schemes, which facilitates the characterization of the peri interactions and also allows for monitoring minute electronic effects induced by different substituents and/or spatial arrangements. ■ INTRODUCTIONDonor−acceptor interactions between phosphines and maingroup elements have received tremendous interest, 1 which has been recently fueled by the discovery that bulky phosphines and boranes may form frustrated Lewis pairs (FLPs) that are able to activate small molecules, such as dihydrogen and carbon dioxide, without the aid of a transition metal. 2 Peri-substituted (ace)naphthylphosphinoboranes comprise regular Lewis pairs or FLPs depending on the nature of the substituents attached to the B and P atoms in 1,8-and 5,6-positions (Chart 1). Sasamori and Tokitoh et al. 3 communicated two 1-dichlorophosphino-8-naphthyl-diarylboranes 1-(Cl 2 P)-8-(R 2 B)-Nap (Ia, R = 3,5-t-Bu 2 C 6 H 3 ; Ib, R = Mes) and later disclosed structural data. 4 Reduction of Ia,b with Mg proceeded with aryl group migration and gave rise to the formation of unique phosphaboranes. 3 Miqueu and Bourissou et al. 5 reported on the three 1-diisopropylphosphino-8-naphthyl-diorganoboranes 1-(iPr 2 P)-8-(R 2 B)-Nap (IIa, R = Mes; IIb, R = Cy; IIc, R 2 = Flu; Flu = 2,2′-biphenylene), which were structurally elucidated. The different P−B peri distances (Å) of 2.108(2) (Ia), 2.892(2) (Ib), 2.173(3) (IIa), 2.076(2) (IIb), and 2.011(2) (IIc) demonstrate that the bulk and electronic effect of the substituents attached to the B and P atoms determines the nature of the peri interaction: namely, if it is dominated by attractive or repulsive forces.Our group described 1-diphenylphosphino-8-naphthyl-dimesitylborane (1-(Ph 2 P)-8-(Mes 2 B)-Nap, IIIa) and the closely related 5-diphenylphosphino-6-acenaphthyl-dimesitylborane (5-(Ph 2 P)-6-(Mes 2 B)-Ace, IIIb), possessing the same substituents at the B and P atoms with albeit quite different B−P peri distances of 2.162(2) and 3.050(3) Å, which is due to the fact that the naphthyl framework accommodates a higher degree of conformational flexibility in comparison to the rigid acenaphthyl framework. 6 Wang et al. also conducted an ...

A series of water-soluble silver(i) complexes of the type [Ag(MTZ)2X] [MTZ = 1-(2-hydroxyethyl)-2-methyl-5-nitro-1H-imidazole (metronidazole drug); X = NO3(-), ClO4(-), CF3COO(-), BF4(-) and CH3SO3(-)] was synthesised by the reactions of various Ag(i) salts with metronidazole (MTZ). All the complexes were characterized by ESI-MS spectrometry, solution NMR ((1)H and (13)C) and IR spectroscopy, and elemental analysis. Further evidence for the formation and molecular structure of all the complexes was provided by X-ray single-crystal crystallography. The different counter ions affect the crystal packing of the complexes and thus have an impact on the final geometries. The antimicrobial activities of the complexes against two Gram-positive strains: Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, three Gram-negative strains: Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922, Proteus hauseri ATCC 13315 and yeast Candida albicans ATCC 10231 were evaluated and compared with antibacterial and antifungal properties of appropriate silver salts, metronidazole and silver sulfadiazine drugs. The newly synthesized compounds exhibited significant antibacterial activity against Gram-positive bacteria, better than the referenced silver sulfadiazine. The best active silver(i)-metronidazole complex contains a methanesulphonate counter-ion. Moreover, the complex inhibited the growth of yeast Candida albicans at a concentration 3-fold lower than that required for silver sulfadiazine. In addition, the complexes containing a tetrafluoroborate and a perchlorate as counter-ions were characterized as effective antibacterial agents against the tested Gram-negative bacteria.

DEDICATION: Dedicated to Wolf-Walther du Mont on the occasion of his 70 th birthday.KEYWORDS: peri-substitution, phosphorus-tellurium, through-space spin-spin coupling, acenaphthene 2 ABSTRACT: A series of peri-substituted phosphorus-tellurium systems R'Te-Acenap-PR 2 (R' = Ph, pAn, Nap, Mes, Tip; R = i Pr, Ph) exhibiting large "through space" spin-spin coupling constants and the "onset" of three-centre four-electron type interactions are presented. The influence of the substituents at the phosphorus and tellurium atoms as well as their behavior upon oxidation (with S, Se) or metalcoordination (Pt, Au) is discussed using NMR spectroscopy, single crystal X-ray diffraction, and advanced DFT studies including NBO, AIM and ELI-D analyses.

Two crystalline modifications of the tripeptide L-Ala-L-Tyr-L-Ala, which have different solvent molecules in the crystal structure (water and ethanol for modifications 1 and 2), were the subject of experimental charge density studies based on high resolution X-ray data collected at ultra-low temperatures of 9 K (1) and 20 K (2), respectively. The molecular structures and the intermolecular interactions were found to be rather similar in the two crystal lattices, so that this study allowed the reproducibility of the charge density of a given molecule in different (but widely comparable) crystalline environments to be examined. With respect to bond topological and atomic properties, the agreement between the two modifications of the title tripeptide was in the same range as found from the comparison with the previously reported results of tri-L-alanine. It follows that the reproducibility and transferability of quantitative topological data are comparable and that within the accuracy of experimental charge density work the replacement of the central amino acid residue L-Ala by L-Tyr has no significant influence, neither on bond nor on the atomic properties of the oligopeptide main chain. Intermolecular interactions in the form of hydrogen bonds were characterized quantitatively and qualitatively by topological criteria and by mapping the charge density distribution on the Hirshfeld surface.