Tetrahedral neutron diffraction studies

The long-known K2Hg(CN)4 and related compounds are still the object of structural studies. Thus, a neutron-diffraction study confirmed the spinel structure of K2Hg(CN)4 at room temperature (298 K) with exactly tetrahedral anions, Hg(CN)42 (r(Hg—C) 215.2, r(C—N) 114.9 pm).112... 

Neutron Diffraction Studies of Tetrahedral Cluster Transition Metal Hydride Complexes HFeCo3(CO)9-(P(OCH3)3)3 and H3Ni4(C5H5)4... 

Interestingly, the isoelectronic iron/ruthenium analogue [HFeRu3(CO)13] 222> has a different structure a tetrahedral geometry with normal CO groups. In a recent neutron diffraction study, the H atom was located on one of the Ru-Ru edges, making Ru-H and Ru-H-Ru parameters of 1.821(3) A and 106.4(2)°, respectively. 

The structure of LiIn(CH3)4 (56) (76) is a three-dimensional network. Each lithium atom is surrounded by a tetrahedral array of carbon atoms. The structure of LiB(CH3)4 (57) (79) consists of planar sheets of lithium atoms bridged by tetramethylboron groups. A unique feature is the presence of both linear and bent Li—C—B units. A neutron diffraction study of LiB(CH3)4 (79) illustrates the Li—H—C interactions present in... 

Thiosulphates and Thionates. A neutron-diffraction study has shown that in barium thiosulphate monohydrate the tetrahedral 8203 anion has the bond lengths S—8=1.979 and 8—0= 1.472-1.483 A the Ba—8 distances are 3.355 and 3.424 A. A crystal structure determination of bis(ethylenethiourea)zinc(ii) thiosulphate has shown that each zinc atom is tetrahedrally surrounded by three sulphur atoms (two from etu and one from the thiosulphate group, with the mean distance Zn—8 = 2.320 A) and one oxygen atom from the 82O3 group. Crystalline Zn(NH3)3(8203),H20 and Cd(NH3)3(8203) have been prepared and characterized spectral data indicate that the 8203 ion is unidentate and is bonded to the metal through sulphur. 

The mechanism of the activation of H2O2 by TS-1 and related catalysts has been the subject of much research using spectroscopic and computational techniques. This has centred on the nature of the active site and its mode of reaction with H2O2, solvents and the organic substrates. Work to elucidate the structure of the active site has concentrated on the coordination chemistry of the titanium. X-ray and neutron diffraction studies, coupled with X-ray absorption, infrared and Raman spectroscopies, give evidence that most of the Ti(IV) in calcined TS-1, in the absence of any adsorbate molecules, is in tetrahedral coordination. Upon addition of one molecule of water, one of the Ti-OSi bonds is hydrolysed and the titanium adopts tetrahedral coordination as Ti(0Si)30H. Addition of a further water molecule gives rise to a pentaco-ordinated titanium. ... 

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