Metal-metal bonds between group 12 metals and tin: structural characterization of the complete series of Sn-M-Sn (M=Zn,Cd, Hg) heterodimetallic complexes

Reaction of the lithium triamidostannate [MeSi[SiMe(2)N(p-Tol)](3)SnLi(OEt(2))] (1) with 0.5 molar equivalents of MCl(2) (M=Zn, Cd, Hg) in toluene afforded the corresponding heterodimetallic complexes [MeSi[SiMe(2)N(p-Tol)](3)Sn](2)M [M=Hg (2), Cd (3), and Zn (4)]. The molecular structures of the mercury and cadmium complexes were determined by X-ray diffraction and found to adopt a linear Sn-M-Sn metal-metal bonded array (d(Sn-Hg) 2.6495(2), d(Sn-Cd) 2.6758(1) A), these being the first Hg-Sn and Cd-Sn bonds to be characterized by X-ray diffraction. That the Hg-Sn bonds are shorter than the Cd-Sn bonds in the isomorphous complexes is attributed to relativistic effects in the mercury system. In contrast, the structure of the Zn analogue is unsymmetrical with one stannate unit being Sn-Zn bonded (d(Sn(1)-Zn) 2.5782(4) A), while the Zn(II) atom bridges two amido functions of the second stannate cage, thus representing a second isomeric form of these complexes. The different degree of metal-metal bond polarity is reflected in the (119)Sn NMR chemical shifts of the three complexes. Variable-temperature NMR studies and a series of (1)H ROESY experiments of the cadmium complex 3 in solution revealed a dynamic exchange between the two isomers.     

Acoustical analysis and model-based sound synthesis of the kantele

The five-string Finnish kantele is a traditional folk music instrument that has unique structural features, resulting in a sound of bright and reverberant timbre. This article presents an analysis of the sound generation principles in the kantele, based on measurements and analytical formulation. The most characteristic features of the unique timbre are caused by the bridgeless string termination around a tuning pin at one end and the knotted termination around a supporting bar at the other end. These result in prominent second-order nonlinearity and strong beating of harmonics, respectively. A computational model of the instrument is also formulated and the algorithm is made efficient for real-time synthesis to simulate these features of the instrument timbre.     

Anomalouse + e − pairs in heavy ion collisions and solar neutrinos

The production of anomalouse ⁺ e ^–pairs in heavy ion collisions and the solar neutrino puzzle are two seemingly unrelated problems of the standard model of electroweak interactions. According to the observations made at Homestake and Kamiokande, the flux of solar neutrinos is too small. Furthermore, the observations made at Homestake (neutrino-nucleon scattering) show anticorrelation of the solar neutrino flux with sunspots, unlike the observations made in Kamiokande (neutrino-electron scattering). According to the previously proposed model inspired by T(opological) G(eometro) D(ynamics), anomalouse ⁺ e ^–pairs result from the decay of the leptopion, which can be regarded as a bound state of color excited electrons. In this paper we show that the generalization of PCAC ideas leads to a prediction for the lifetime and production cross section of the leptopion in agreement with data. The model is also consistent with constraints coming from Babbha scattering and supernova physics. Leptopion exchange implies a new weak interaction between leptons at low cm energies (of the order of a few MeVs), which explains the Kamiokande-Homestake puzzle. Part of the solar neutrinos are transformed in the convective zone of the Sun to right-handed neutrinos inert with respect to ordinary electroweak interactions, but interacting with electrons via leptopion exchange so that they are observed in Kamiokande. A correct average value for the neutrino flux at Kamiokande is predicted using as input the Homestake flux, and the anticorrelation with sunspots in Kamiokande is predicted to be considerably weaker than in Homestake.     

Intensity fluctuations and degree of polarization in three-dimensional thermal light fields

The normalized intensity fluctuations of arbitrary electromagnetic wave fields obeying Gaussian statistics are expressed in terms of the three-dimensional degree of polarization. This general formulation implies an important physical result concerning the polarization of planar fields and the dimensionality of the formalism. The results are expected to be particularly useful in intensity interferometry.     

An efficient synthesis of phthalocyanines based on an unprecedented double-addition of oximes to phthalonitriles

A novel and efficient method is reported for the preparation of phthalocyanines from phthalonitrile or its derivatives which utilizes low-cost reagents of hydrolytic stability, high simplicity, and easy accessibility, i.e., oximes, and proceeds via an unprecedented double addition of oximes to the nitrile group.     

Syntheses and structural characterization of the heavier alkali-metal stannates bearing the tripodal triamino framework: structural trends in the series of [MeSi(SiMe2N(4-CH3C6H4))3Sn][M] (M = Na,K, Rb)

Treatment of the lithium stannate [MeSi(SiMe(2)N(4-CH(3)C(6)H(4)))(3)SnLi(OEt(2))] (1) with AgCl yielded the corresponding distannane [MeSi(SiMe(2)N(4-CH(3)C(6)H(4)))(3)Sn](2) (2) as the product of an oxidative coupling in good yield. The distannane (2) underwent reductive cleavage with the heavier alkali metals (sodium, potassium, rubidium) in a non-coordinating solvent (toluene or cyclohexane), to afford the solvate-free stannates(II) [MeSi(SiMe(2)N(4-CH(3)C(6)H(4)))(3)Sn][M] (M = Na (3), K (4), and Rb (5)), which were structurally characterized. The Na atom in 3 is directly bonded to two of the three amido-N atoms of the stannate cage and additionally solvated by pi-coordination of a tolyl substituent of a neighboring stannate cage. In contrast, the group 1 metal cations in the two isomorphous compounds 4 and 5 are further removed from the nitrogen functions and are pi-coordinated by three tolyl arene rings. The Sn-K distances in 4 were found to be 3.635 and 3.870 A, whereas the Sn-Rb contacts in 5 are 3.708 and 3.908 A; these are the first such Sn-Rb bonding contacts to be characterized in a molecular compound by X-ray diffraction.     

A high-resolution study of the 14.4-μm infrared band of deuterofluoroform

The FT-IR spectrum of the ν₃ parallel band of deuterofluoroform has been recorded at a resolution of 0.0045 cm^?1. Nine independent spectral parameters were determined which reproduce some 650 observed wavenumbers with a standard error of 3 × 10^?4 cm^?1. The constants derived for the ν₃ band are (in cm^?1): ν₀ = 694.2822(3); B₀ = 0.3309321(9); B₃ = 0.3302464(11); α^B = 6.859(10) × 10^?4; α^C = 1.429 × 10^?4; D₃^J = 3.168(3) × 10^?7; D₀^J = 3.188(3) × 10^?7; D_JK³ = 4.766 × 10^?7; D_JK⁰ = 4.864 × 10^?7; and D_K⁰ ? D_K³ = 2 × 10^?10.