Slipped stack

PXX groups in complexes 87-90 can also slipped-stack to form columns located between the Pc columns and sheets. Since the crystal structures and supramolecular assembles of this type of phthalocyanine were well summarized in 2001 [12] and 2005 [79], we will present briefly only one typical Pc %-% supramolecular structure that has not been included in the previous section. As shown in Fig. 23, the Pc units in 89 form a 2D sheet along the ac plane. The overlap mode is type G Pc %-% interactions along both the a- and c-axes. This sheet further interacts with another sheet by type C overlap, forming a double sheet. 

Fig. 8 Local transmission pictures in a superposed benzenoid structure. As the two rings change geometry from an eclipsed pseudo para geometry (upper left) through an eclipsed pseudo meta geometry to a slip-stacked structure to a single tunneling pathway, the transmission at the Fermi energy increases hy roughly a factor of ten. Reprinted with permission from G. C. Solomon et al. J. Am. Chem. Soc. (2010) 132, 7887-7889. Copyright 2011 American Chemical Society...

Finally, a metal- -T 6-arene interaction that generates a supramolecular onedimensional array has been reported in the solid-state structure of the (2,6-diphe-nylpyridine)gold(III) derivative [Au(CN) 2,6-NC5H3(C6H4)2-C,C, N [ [66]. Its crystal structure shows that the planes of the planar molecules are parallel, but slip-stacked via intermolecular Au- -T 6-arene contacts in which the distance between the gold atom and the centroid of the arene is 3.428 A. A representation of this structure is shown in Figure 5.35. 

The second structural motif is exemplified by Ni(bqd)2 (bqd= 1,2-benzoquinonedioximato) (Figure 23). The planar molecules (Table 54) are in a slipped-stacked (SS) arrangement which makes the Ni—Ni directions inclined with respect to the stacking axis. In this type of complex the Ni—Ni distances are longer, the packing is also more efficient and no channels are present. The complexes with SS structure are generally insulators. 

Ni—Ni distance refers to intermolecular metal-metal interaction N (am) and N (ox) mean amine and oxime nitrogen respectively MOM = metal over metal structure SS = slipped-stacked structure. 

The first structural report on a phthalocyanine complex concerned [Ni(pc)J (Table 110 I).2878 In the crystal lattice of this compound the square planar macrocycles are arrayed in slipped stacks such that the distance between the molecular planes along the perpendicular direction is 388 pm. [Ni(pc)] may be prepared by a variety of methods 2873,2871 2880 a convenient one is heating a foil of elemental nickel in o-cyanobenzamide at 270 °C (Scheme 60).2881 [Ni(pc)] is insoluble in the most common organic solvents, but soluble in concentrated sulfuric acid from which it is reprecipitated unchanged upon dilution. This complex is thermally very stable and may be sublimed in vacuo. The reduction of [Ni(pc)] can be accomplished by chemical or electrochemical methods and results in ligand-based reduced anions [Ni(pc)]" ( = 1, 2). Analogously, the electrochemical oxidation results in the oxidized ligand. 3... 

Ni—N, 194,196 planar conformation of macrocycle slipped-stack 2888,2889 arrangement of the molecules... 

Scheme 10 Simplified through-space exchange mechanisms for benzyl radical models, comparison to a dicarbene stacking model, and ambiguity of exchange in a slip stacked dyad.

The structure of diradical benzo-bis(l,3,2-dithiazolyl) 7 consists of discrete (undimerized) molecules which lie on a center of inversion the molecules are planar with the largest deviation from the mean plane being 0.014(3) A. The molecules form strongly slipped stacks along the X d rect on <1997JA2633>. The structure of pyrazinodithiazolyl 9 determined at various (95 and 293 K) temperatures consists of slipped stacks of Jt-dimers <2004JA8256>. 

Fig. 14.12 9,10-Dichloroanthracene (17), 9,10-dibromoanthra-cene (18) and 9,10-diiodoanthracene (19) showing slipped-stacked arrangement and interplanar spacings.

Fig. 2a-c. Some structural motifs for the parallel stacking of planar metallomacrocycles. Motif (a), which is the most important, is often called the metal-over-metal arrangement. Motif (b) is often called the slipped-stack arrangement. Many other motifs are possible, (c) being but one example... 

Fig. 3. Donor-acceptor projections for [Pd(bqd)2][TCNQ] and [perylene][Ni(tfd)2] (inset) showing the unsymmetrical molecular overlaps resulting from the slipped stacking arrangement (Refs. 35, 33 (inset))...

All of the 1 1 metal dithiolene systems listed in Table 7 are composed of a phos-phonium or ammonium cation and a metal111 bis-dithiolene monoanion. These compounds are structurally very similar, consisting of slipped stacks of metal dithiolene anions which are associated in pairs the stacks are surrounded by non-interacting cations. A view of a representative unit cell for this type of system is shown in Fig. 15. Only [n-Bu4N][Cu(mnt)2]92) displays a slightly different association of anion pairs in the... 

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