Matrix Infrared Spectroscopic and Theoretical of the Difluoroamino Metal Fluoride Molecules: F₂NMF (M = Cu, Ag, Au)

The difluoroamino coinage metal fluoride molecules F₂NMF (M = Cu, Ag, Au) have been made via spontaneous reactions of coinage metals and NF₃ in solid argon and neon matrixes during sample annealing without formation of the M­(NF₃) complexes. Comparisons between the matrix infrared spectra and the density functional frequency calculations provide strong support for identification of the F₂NMF molecules, which are found to have doublet ground states with <i>C</i>_2<i>v</i> or near <i>C</i>_2<i>v</i> geometries. The F₂NCuF molecule can isomerize to the less stable FNCuF₂ isomer upon UV–visible irradiation, while no similar reactions were observed for the silver and gold species. The M–N bonds in the F₂NMF molecules are stronger than those in the FNMF₂ isomers with the Ag–N bond being longest and weakest in both cases

Formation and Characterization of the Uranyl–SO₂ Complex, UO₂(CH₃SO₂)(SO₂)⁻

The uranyl–SO₂ adduct, UO₂(CH₃SO₂)­(SO₂)⁻, was prepared and characterized by mass spectrometric studies as well as by density functional theory. Collision induced dissociation of UO₂(CH₃SO₂)₂^– in an ion trap resulted in the formation of UO₂(CH₃SO₂)­(SO₂)⁻, which spontaneously reacted with O₂ to give UO₂(CH₃SO₂)­(O₂)⁻, with SO₂ released. The UO₂(CH₃SO₂)­(SO₂)⁻ complex is computed to have a triplet ground state at the B3LYP level, and the SO₂ ligand is coordinated to uranium through two oxygen atoms, similar to the coordination mode of SO₂ in its complexes with hard metals. On the basis of the calculated geometric parameters and vibrational frequencies of the SO₂ ligand, the UO₂(CH₃SO₂)­(SO₂)⁻ complex can be considered as a U^VO₂⁺ cation coordinated by SO₂^– and CH₃SO₂^– anions. The UO₂(CH₃SO₂)­(O₂)⁻ complex is computed to have a peroxo ligand, suggesting that U^V in UO₂(CH₃SO₂)­(SO₂)⁻ is oxidized to the U^VI state upon O₂ substitution for SO₂

Crown Ether Complexes of Uranyl, Neptunyl, and Plutonyl: Hydration Differentiates Inclusion versus Outer Coordination

The structures of actinyl–crown ether complexes are key to their extraction behavior in actinide partitioning. Only UO₂(18C6)²⁺ and NpO₂(18C6)⁺ (18C6 = 18-Crown-6) have been structurally characterized. We report a series of complexes of uranyl, neptunyl, and plutonyl with 18-Crown-6, 15-Crown-5 (15C5), and 12-Crown-4 (12C4) produced in the gas phase by electrospray ionization (ESI) of methanol solutions of AnO₂(ClO₄)₂ (An = U, Np, or Pu) and crown ethers. The structures of 1:1 actinyl–crown ether complexes were deduced on the basis of their propensities to hydrate. Hydration of a coordinated metal ion requires that it be adequately exposed to allow further coordination by a water molecule; the result is that hydrates form for outer-coordination isomers but not for inclusion isomers. It is demonstrated that all the actinyl 18C6 complexes exhibit fully coordinated inclusion structures, while partially coordinated outer-coordination structures are formed with 12C4. Both inclusion and outer-coordination isomers were observed for actinyl–15C5 complexes, depending on whether they resulted from ESI or from collision-induced dissociation. Evidence for the formation of 1:2 complexes of actinyls with 15C5 and 12C4, which evidently exhibit bis-outer-coordination structures, is presented

Using Buffers in Trust Aware Relay Selection Networks with Spatially Random Relays

IEEE It is well recognized that using buffers in relay networks significantly improves the transmission reliability, which is often at the price of higher packet delay. Existing buffer-aided relay networks are all based on the physical links among cooperative nodes. This may however lead to performance degradation in practice, because that cooperative nodes may not trust each other for cooperation even though their physical connection are strong. In this paper, we propose a novel buffer-aided relay selection scheme to align data transmission with both strong and trusted links. By maintaining the buffer lengths as close as possible to the newly introduced target buffer lengths, the proposed scheme is able to balance the outage performance and packet delay. Both the outage probability and average packet delay are analyzed for spatially random relays. Particularly we show that outage performance may have error floors because of the trusts. The analysis shows that using buffers in trust aware relay networks is able to either increase the diversity order or lower the error floor of the outage probability

Coordination Structure and Fragmentation Chemistry of the Tripositive Lanthanide-Thio-Diglycolamide Complexes

Tripositive Ln­(TMTDA)₃³⁺ complexes (Ln = La–Lu except Pm, TMTDA = tetramethyl 3-thio-diglycolamide) were observed in the gas phase by electrospray ionization of LnCl₃ and TMTDA mixtures. Collision-induced dissociation (CID) was employed to investigate their fragmentation chemistry, which revealed the influence of metal center as well as ligand on the ligated complexes. Ln­(TMTDA)₂­(TMTDA-45)³⁺ resulting from C_carbonyl–N bond cleavage of TMTDA and hydrogen transfer was the major CID product for all Ln­(TMTDA)₃³⁺ except Eu­(TMTDA)₃³⁺, which predominantly formed charge-reducing product Eu^II(TMTDA)₂²⁺ via electron transfer from TMTDA to Eu³⁺. Density functional theory calculations on the structure of La­(TMTDA)₃³⁺ and Lu­(TMTDA)₃³⁺ revealed that Ln³⁺ was coordinated by six O_carbonyl atoms from three neutral TMTDA ligands, and both complexes possessed <i>C</i>_3<i>h</i> symmetry. The S_ether atom deviating from the ligand plane was not coordinated to the metal center. On the basis of the CID results of Ln­(TMTDA)₃³⁺, Ln­(TMGA)₃³⁺, and Ln­(TMOGA)₃³⁺, the fragmentation chemistry associated with the ligand depends on the coordination mode, while the redox chemistry of these tripositive ions is related to the nature of both metal centers and diamide ligands

Reactions of Laser-Ablated Aluminum Atoms with Cyanogen: Matrix Infrared Spectra and Electronic Structure Calculations for Aluminum Isocyanides Al(NC)_1,2,3 and Their Novel Dimers

Laser-ablated Al atoms react with (CN)₂ in excess argon during condensation at 4 K to produce AlNC, Al­(NC)₂, and Al­(NC)₃, which were computed (B3LYP) to be 27, 16, and 28 kJ/mol lower in energy, respectively, than their cyanide counterparts. Irradiation at 220–580 nm increased absorptions for the above molecules and the very stable Al­(NC)₄^– anion. Annealing to 30, 35, and 40 K allowed for diffusion and reaction of trapped species and produced new bands for the Al­(NC)_1,2,3 dimers including a rhombic ring core (C)­(AlN)₂(C) with C’s attached to the N’s, a (NC)₂Al­(II)–Al­(II)­(NC)₂ dimer with a computed Al–Al length of 2.557 Å, and the dibridged Al₂(NC)₆ molecule with a calculated <i>D</i>_2<i>h</i> structure and rhombic ring core like Al₂H₆. In contrast, the Al­(NC)₄^– anion was destroyed on annealing presumably due to neutralization by Al⁺. B3LYP calculations also show that aluminum chlorides form the analogous molecules and dimers. In our search for possible new products, we calculated Al­(NC)₄ and found it to be a stable molecule, but it was not detected here

Matrix Infrared Spectra of Manganese and Iron Isocyanide Complexes

Mono and diisocyanide complexes of manganese and iron were prepared via the reactions of laser-ablated manganese and iron atoms with (CN)₂ in an argon matrix. Product identifications were performed based on the characteristic infrared absorptions from isotopically labeled (CN)₂ experiments as compared with computed values for both cyanides and isocyanides. Manganese atoms reacted with (CN)₂ to produce Mn­(NC)₂ upon λ > 220 nm irradiation, during which MnNC was formed mainly as a result of the photoinduced decomposition of Mn­(NC)₂. Similar reaction products FeNC and Fe­(NC)₂ were formed during the reactions of Fe and (CN)₂. All the product molecules together with the unobserved cyanide isomers were predicted to have linear geometries at the B3LYP level of theory. The cyanide complexes of manganese and iron were computed to be more stable than the isocyanide isomers with energy differences between 0.4 and 4 kcal/mol at the CCSD­(T) level. Although manganese and iron cyanide molecules are slightly more stable according to the theory, no absorption can be assigned to these isomers in the region above the isocyanides possibly due to their low infrared intensities

Gas Phase Uranyl Activation: Formation of a Uranium Nitrosyl Complex from Uranyl Azide

Activation of the oxo bond of uranyl, UO₂²⁺, was achieved by collision induced dissociation (CID) of UO₂(N₃)­Cl₂^– in a quadrupole ion trap mass spectrometer. The gas phase complex UO₂(N₃)­Cl₂^– was produced by electrospray ionization of solutions of UO₂Cl₂ and NaN₃. CID of UO₂(N₃)­Cl₂^– resulted in the loss of N₂ to form UO­(NO)­Cl₂^–, in which the “inert” uranyl oxo bond has been activated. Formation of UO₂Cl₂^– via N₃ loss was also observed. Density functional theory computations predict that the UO­(NO)­Cl₂^– complex has nonplanar <i>C_s</i> symmetry and a singlet ground state. Analysis of the bonding of the UO­(NO)­Cl₂^– complex shows that the side-on bonded NO moiety can be considered as NO^3–, suggesting a formal oxidation state of U­(VI). Activation of the uranyl oxo bond in UO₂(N₃)­Cl₂^– to form UO­(NO)­Cl₂^– and N₂ was computed to be endothermic by 169 kJ/mol, which is energetically more favorable than formation of NUOCl₂^– and UO₂Cl₂^–. The observation of UO₂Cl₂^– during CID is most likely due to the absence of an energy barrier for neutral ligand loss

Dual Antenna Selection in Self-Backhauling Multiple Small Cell Networks

This letter investigates self-backhauling with dual antenna selection at multiple small cell base stations. Both half-duplex (HD) and full-duplex (FD) transmissions at the small cell base station are considered. Depending on instantaneous channel conditions, the FD transmission can have higher throughput than the HD transmission, but it is not always the case. Closed-form expressions of the average throughput are obtained and validated by the simulation results. In all cases, the dual receive and transmit antenna selection significantly improves backhaul and data transmission, making it an attractive solution in practical systems

Physical Layer Network Security in the Full-Duplex Relay System

This paper investigates the secrecy performance of full-duplex relay (FDR) networks. The resulting analysis shows that FDR networks have better secrecy performance than half duplex relay networks, if the self-interference can be well suppressed. We also propose a full duplex jamming relay network, in which the relay node transmits jamming signals while receiving the data from the source. While the full duplex jamming scheme has the same data rate as the half duplex scheme, the secrecy performance can be significantly improved, making it an attractive scheme when the network secrecy is a primary concern. A mathematic model is developed to analyze secrecy outage probabilities for the half duplex, the full duplex and full duplex jamming schemes, and the simulation results are also presented to verify the analysis