Canted structure

Figure 6.4. Illustration of the canted structure formed upon adsorption of the n-alkanethiols, CH3(CH2) SH, on copper and silver.

A linear relationship is obtained with a slope of 7.7, predicting a magnetisation value of 10 /Ib per formula unit for total Zn substitution, X = 1, as shown by the broken lines in Fig. 4.21. This relationship is not followed over the entire composition range, however. As Zn content increases, A-O-B interactions become too weak and B-O-B interactions begin to dominate. Instead of a collinear, antiparallel alignment, a canted structure appears, where spins in B sites are no longer parallel. Fig. 4.22. Evidence of this triangular structure has been observed by neutron diffraction (Satya Murthy et al, 1969) a theoretical analysis showed that departure from collinear order depends on the ratio of the A-O-B to... 

Defects in ferrimagnetic structures often lead to noncollinear (canted) spin structures. For example, a diamagnetic substitution or a cation vacancy can result in magnetic frustration which leads to spin-canting such that a spin may form an angle 6c with the collinear spins in the sample [80, 81]. Similarly, the reduced number of neighbor ions at the surface can also lead to spin-canting [80-83]. 

Table 1. Canting angles 0(hkl) (degree) for various reflections (hkl), with nuclear structure factors and scaled scalar magnetic structure factors (Bohr magneton). 

Scheme 2 Four common packing motifs of the BEDT-TTF molecule. The black bars represent and end-on view of the molecule, looking down the long molecular axis. The a-phase, which is quite similar to the 0-phase, is characterized as a herringbone structure, the P -phase contains stacks of slipped dimers, the K-phase contains orthogonally arranged dimers, and the P"-phase is characterized by canted stacks of donor molecules...

Love and coworkers have reported a series of dinuclear cobalt complexes derived from a rigid binucleating macrocycle H4L 18 as shown in Fig. 26 (150). The synthesis of the dicobalt complex [Co2(L18)] (36) was achieved by an anaerobic transamination reaction between H4L18 and [Co(thf) N(SiMe3)2 2] in THF. The unsaturated species 36 forms a bis(pyridine) adduct, 36 py2 (py — pyridine), which has a cleft-like structure reminiscent of pacman diporphyrin complexes (151,152). Both cobalt ions are square pyramidal, with Col and Co2 displaced out of the N4-basal planes by 0.17 and 0.18 A, respectively. The apical sites are occupied by pyridine nitrogen atoms that are exo and endo to the cleft. Interestingly the endo pyridine is canted and reflects the... 

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