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Boron is an element that has ability to build strong and highly directional bonds with boron itself. As a result, boron atoms form diverse structural motifs, ultimately can yield distinct nano structures, such as planar, quasi-planar, convex, cage, open-cage, tubular, spherical., ring, dome-like, shell, capsule, and so on, i.e., it can take almost any shape. Therefore, a deep understanding of the physical and chemical properties becomes important in boron cluster chemistry. Electronic and geometric structures, total and binding energies, harmonic frequencies, point symmetries, charge distributions, dipole moments, chemical bondings and the highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps of neutral B-n (n=13-20) clusters have been investigated by, density functional theory (DFT), B3LYP with 6-311++G(d,p) basis set. Furthermore, the first and the second energy differences are used to obtain the most stable sizes. We have observed that almost all physical properties are size dependent, and double-ring tubular form of B-20 has the highest binding energy per atom. The icosahedral structure with an inside atom is found as impossible as a stable structure for the size thirteen. This structure transforms to an open-cage form. The structural transition from two-dimensional to three-dimensional is found at the size of 20 and consistent with the literature. The calculated charges by the Mulliken analysis show that there is a symmetry pattern with respect to the x-z and y-z planes for the charge distributions. The unusual planar stability of the boron clusters may be explained by the delocalized pi and sigma bonding characteristic together with the existence of the multicentered bonding. The results have been compared to available studies in the literature.

WOS: 000376050700031, In this study a new monospirocyclic phosphazene derivative, 4',4',6',6'-tetrachloro-3-(2-methoxyethyl)3H,4H-spiro [1,3,2-benzoxazaphosphinine-2,2'- [1,3,5,2,4,6] triazatriphosphinine] (SP1) was synthesized from the reaction of hexachlorocyclotriphosphazene (N3P3CI6) with N/0 donor-type, 2-{[(2-Metoxyethyl) amino]methylphenol. The structural investigations of the compound were verified by elemental analyses, MS, FFIR, 1H, 13C, 11 --P NMR spectroscopy and the single crystal X-ray diffraction analysis. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method (DFT) using 6-311++G (d, p) basis set. The complete assignments of all vibrational modes were performed on the basis of the total energy distributions (TED). Isotropic chemical shifts (31P, 1H and 13C NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. Theoretical calculations of bond parameters, harmonic vibration frequencies and nuclear magnetic resonance are in good agreement with experimental results. The electrophilic and nucleophilic attack centers in SP1 were predicted with the local softness values (sit, and si) of individual atoms and it is confirmed that P atoms of the PCl2 groups are nucleophilic attack centers. (C) 2016 Elsevier B.V. All rights reserved., Kirikkale University, Scientific Research Projects Coordination Unit [2012/14], The authors gratefully acknowledge the financial support from the "Kirikkale University, Scientific Research Projects Coordination Unit" (grant No. 2012/14).