Diana Hoppe

Nb and Ta adducts: connecting d0 metal chlorides and phosphorus sulfide cages.

Phosphorus sulfide cages alpha-P(4)S(4), alpha-P(4)S(5), beta-P(4)S(5), and beta-P(4)S(6) and transition-metal chlorides TaCl(5) and NbCl(5) form molecular adducts in CS(2)/n-hexane. The crystal structures of the adducts (TaCl(5))(alpha-P(4)S(4)), (TaCl(5))(alpha-P(4)S(5)), (TaCl(5))(beta-P(4)S(5)), (NbCl(5))(beta-P(4)S(5)), and (TaCl(5))(beta-P(4)S(6)) are reported and their conformation and energetic stability are discussed on the basis of ab initio electronic structure calculations. Furthermore bond lengths of coordinated and noncoordinated phosphorus sulfide cages obtained from experiment and theory are compared, emphasizing the changes within the cages that emerge upon coordination.

Phosphorus-rich phosphorus selenides P14+xSe (x=1, 5)

Abstract New phosphorus-rich phosphorus selenides P14+xSe (x = 1, 5) were synthesized by reaction of amorphous red phosphorus and SeO2. The crystal structures of P15Se and P19Se were solved from single-crystal X-ray data (space group Pnma (No. 62); P15Se: a = 9.963(2) Å, b = 3.231(1) Å, c = 13.412(3) Å; P19Se: a = 9.917(2) Å, b = 3.230(1) Å, c = 13.410(3) Å). The structures consist of pentagonal tubes packed collaterally with two-dimensional disorder, which was confirmed by TEM investigations.

Structural Characterization of Phosphorus‐Based Networks and Clusters: 31P MAS NMR Spectroscopy and Magnetic Shielding Calculations on Hittorf’s Phosphorus

The (31)P MAS NMR spectrum of Hittorfs phosphorus has been measured and assigned to the 21 crystallographically distinct phosphorus atoms based on two-dimensional dipolar correlation spectroscopies. Application of such 2D techniques to phosphorus-based networks is particularly challenging owing to the wide chemical shift dispersions, rapid irreversible decay of transverse magnetization, and extremely slow spin-lattice relaxation in these systems. Nevertheless, a complete assignment was possible by using the combination of correlated spectroscopy (COSY) and radiofrequency-driven dipolar recoupling (RFDR). The assignment is supported further by DFT-based ab initio chemical shift calculations using a cluster-model approach, which gives good agreement between experimental and calculated chemical shift values. The (31)P chemical shifts appear to be strongly correlated with the average P-P bond lengths within the P(P(1/3))(3) coordination environments, whereas no clear dependence on average P-P-P bond angles can be detected. Calculations of localized Kohn-Sham orbitals reveal that this bond-length dependence is reflected in energy variations in the corresponding localized p-p-σ orbitals influencing the paramagnetic deshielding contribution in Ramseys equation. In contrast, the contributions of the lone pairs to shielding differences are small and/or do not vary in a systematic manner for the different crystallographically distinct phosphorus sites. The combined spectroscopic and quantum chemical approach applied here and the increased theoretical understanding of (31)P chemical shifts will facilitate the structural elucidation of other phosphorus-based clusters and networks.

Adduct Compounds (MCl5)2(β-P4Ch4) with M = Nb, Ta and Ch = S, Se

Adduct compounds of the general composition (MCl5)2(β -P4Ch4), M = Nb, Ta and Ch = S, Se, were obtained from solutions of M2Cl10 and P4Ch3 in CS2 / n-hexane. The compounds are isotypic with (NbCl5)2(β -P4S4), crystallizing in the monoclinic space group P 21/n (no. 14) with Z = 4. The lattice constants are a = 6.304(2), b = 13.071(3), c = 26.552(6) Å , β = 93.74(3)◦, V = 2183(1) Å3 for (TaCl5)2(β -P4S4), a = 6.360(2), b = 13.322(3), c = 26.710(6) Å , β = 93.81(3)0, V = 2258(1) Å3 for (TaCl5)2(β -P4Se4), and a = 6.334(2), b = 13.267(6), c = 26.583(7) Å , β = 93.71(3)0, V = 2229(2) Å3 for (NbCl5)2(β -P4Se4). The adduct molecules consist of two MCl5 units which are linked with two of the basal phosphorus atoms of the central β -P4Ch4 cage. Graphical Abstract Adduct Compounds (MCl5)2(β-P4Ch4) with M = Nb, Ta and Ch = S, Se