Centrosymmetric dimer observables

Figure 12.9 illustrates the neighboring molecules in the crystal structure of trichloroacetic acid. One can observe the centrosymmetric dimers of acid connected... 

Nitrate anions can be substituted on bismuth nitrate by reaction with polyethylene glycols effecting deprotonation (or ionization) of one end of the ligand chain (101). Centrosymmetric dimers of the general form 29 are observed, with nitrate anions asymmetrically coordinated, staggered, and trans to one another [Bi-0 2.240(l)-2.28(2) A] in [Bi(N03)2(Heo3)]2, [Bi(N03)2(Heo4)]2(MeOH)2, and [Bi(N03)2... 

As expected from the presence of the potential NH donor groups and the potential oxygen acceptor atoms, the zwitterions in the crystals of 6a-0.7CH3CN and 6b form N-H - O hydrogen bonds. In the crystal of 6a-0.7CH3CN, tetramers consisting of two molecules A and two molecules B were observed, whereas the crystal lattice of 6b is built up by centrosymmetric dimers. 

The metal complex in [RhClj(C8Hi502)(4-methylpyridine)j2,(4-methyl-pyridine) is a centrosymmetric dimer with two bridging chlorine atoms the molecular structure, with the observed bond lengths, is shown in Figure... 

One of the shortest N ->Ln bonds has been observed in the centrosymmetrical dimeric structure of [(MeC5H4)2YbNH2]2 [46]. The Yb-N distances in this molecule (2.29 and 2.32 A) are almost equal to each other. The average Yb-C T] -distance and the (MeC5H4 centroid)Yb(MeC5H4 centroid) angle are 2.62 A and 130.5°. 

The crystal structures of Ag(Gly)69 and Ag(HGly)NOs405 have been determined. For the latter compound, the silver ions bridged centrosymmetrically related carboxyl groups to form dimers of glycine. The actual composition was best represented as (NH3CH2C02 Ag+)2(NOi )2. Below —55 °C the compound was found to be ferroelectric. It was the first crystal containing either silver or the nitrate ion in which ferroelectridty was observed.406... 

The structure of 73 was substantiated spectroscopically (5 nB = 82.5 ppm) and confirmed crystallographically. A centrosymmetric chloro-bridged dimeric structure with tricoordinate copper centers was observed. The pendant character of the borane is apparent from the rather long the B- Cu (3.05 A) and B- Cl (4.06 A) distances associated with a trigonal planar geometry around boron. Compared to related mononuclear palladium and rhodium complexes (see Section IV.B), the presence of the chloro-bridge disfavors the formation of Cl-B interactions (coordination mode F) in 73. 

At last, in his model, the ACF playing the role of [GD iv(Vj] in Eq. (309), is extracted from the two other models playing the role of [G rmi(f)] and [O0(t)IP]T. They give a numerical expression, which after Fourier transform, is assumed to give the peeled-off spectral density, that is, the SD of the H-bonded centrosymmetric cyclic dimer that would be observed if the Fermi resonances were missing. 

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