Lengths neutron diffraction

The presence or absence of hydrogen bonds in solid hydroxides, which is not trivial to decide in all cases, can be proved by the observed interionic H(D) X distances, the OH or OD stretching frequencies, and their temperature dependence [50,53]. In the case of OH" OH" hydrogen bonds, to which the discussion is restricted in this paragraph, H(D) - O bond lengths (neutron diffraction data, X-ray data and 0---X distances are much less suitable for such... 

F H, O Kennard, D G Watson, L Brammer, A G Orpen and R Taylor 1987.1 ables of Bond Lengths determined by X-ray and Neutron Diffraction. 1. Bond Lengths in Organic Compounds. Journal of he Chemical Society Perkin Transactions 11 51-519. 

O-H bond length was 1.08A, a value similar to that previously reported by Szy-tula et al. in a neutron diffraction study of Ni(OH)2 [23]. The O-H bond is both well crystallized and as precipitated materials is parallel to the c-axis. The difference between well-crystallized and as precipitated material is important since the well-crystallized material is not electrochemi-cally active. The differences between the materials are attributed to a defective structure that accrues from the large concentration of surface OH ion groups in the high-surface-area material [22]. These are associated with absorbed water. This is a consistent with an absorption band in the infrared at 1630cm 1. This is not seen in the well-crystallized material. 

It is a somewhat surprising fact that information about vibrational frequencies and bond lengths in very common and important ions is very sparse. Clearly, many more such determinations are necessary. Only this year, for example, have data become available which enable metal-ligand displacements on electron removal for the aquo Fe(II)/Fe(III) and Co(II)/Co(III) systems to be obtained. In view of the importance of these partially unpublished data, I have reproduced them in Table VI. The values of A for the Fe and Co systems are 0.128-0.137, and 0.208 8 respectively. The variability of the Fe results points to the fact that caution must be exercised in using data obtained in crystal lattices for a solution environment. Spin-polarized neutron diffraction studies on the structure of solu-... 

Figure 57 The molecular structure of [Fe(dppe)2(H2) (H)]+. The H-H bond length is 0.82 A at the neutron diffraction and 0.87 A at X-ray diffraction, respectively...

Dimensions Bond length, Proton location, / a-h Bond angle, L AHB X-Ray or neutron diffraction... 

Since these early X-ray diffraction experiments, several other crystals have been subjected to analysis by X-ray and neutron diffraction and the F bond length has remained virtually unchanged. The location of the proton has been the point at issue. Early ir studies on KHF2 were interpreted as evidence for a double minimum potential well (Ketelaar, 1941 Glocker and Evans, 1942), but later studies questioned this (Pitzer and Westrum, 1947 Cote and Thompson, 1951 Newman and Badger, 1951) and led to a revision of earlier opinions (Ketelaar and Vedder, 1951). 

Glucose. The improvement in the calculated structure which is obtained by use of the new PEFs is indicated in Table II which includes comparison with previous results (8,11). The measured values pertain to neutron-diffraction data for a-glucose (12) and x-ray diffraction data for /9-glucose (13). The separate treatment of anomer carbon implies that the largest deviation in bond length is no longer found for the anomeric C-0. 

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