Solid-state complexation

The structure of the active catalyst and the mechanism of catalysis have not been completely defined. Several solid state complexes of BINOL and Ti(0-/-Pr)4 have been characterized by X-ray crystallography.158 Figure 2.4 shows the structures of complexes having the composition (BIN0Late)Ti2(0-/-Pr)6 and (BINOLate)Ti3(O-/-Pr)10. 

Table 4. Formation of solid-state complexes between cyclodextrins and hydrophobic poly-mers/oligomers with various chain sectional area... 

As chiral molecules, CD hosts are one of the best chiral selectors [23]. They can also induce circular dichroism signal in an achiral guest. As shown by Zhang and Nau [24] for the complexes of p-CDwith bicyclic azaalkanes 290 or 291, this effect may allow one to determine the orientation of the latter molecule in the CD cavity. An interesting example of the influence of 11 on the guest conformation was reported by Brett and coworkers [25]. They have shown that p-amino-/ -nitrobiphenyl 292, which is planar in the solid state, becomes nonplanar in the solid state complex with 3-CD. 

Selected nickel(II) complexes with C-substituted diamines are listed in Table 41. In solution the square planar coordination is favoured,700 while both square planar and six-coordinate complexes have been isolated in the solid state. Complexes with l,2-diphenyl-l,2-diaminoethane (stilbendiamine, stien) and l-phenyl-l,2-diaminoethane have been widely studied.701-706 Using CI2CHCO2 as counterion, two complexes have been obtained with the former ligand, one blue, monoclinic, P2Jc ( Ueif = 3.16BM), the other yellow-green, triclinic,... 

According to X-ray diffraction data, in the solid-state complex 87 adopts a six-membered metallacyclic structure, as the result of P-Pd-Cl-B bridging coordination. The interaction of the borane moiety with the chlorine atom is apparent from the short Cl-B distance (2.165(2) A) and the pyramidalization of the boron environment (EBa = 349.1°). The bridging coordination of the Pd-Cl bond by the PB 7b contrasts with the B-pendant coordination mode adopted by complex 72, deriving from the related ligand 7e featuring mesityl groups at boron (see Section IV.A). This illustrates the role of steric factors in the participation, or not, of the Lewis acid in the coordination assembly. 

In a similar way it is widely believed that the mutual interaction of two binding partners in solution involves just one binding mode (the so-called associated-dissociated two-state postulate). Such an assumption appears to be a prerequisite to informed improvement of the molecular design and is based on a plentitude of solid-state complex structures and additionally on the observation of massive exothermicities (negative AH) in many, but by no means in all, cases of molecular complex formation. 

Figure 13. A view of one unit of the chain structure created with the solid state complexation of KF by 40.91...

Three different ways have been developed to produce nanoparticle of PE-surfs. The most simple one is the mixing of polyelectrolytes and surfactants in non-stoichiometric quantities. An example for this is the complexation of poly(ethylene imine) with dodecanoic acid (PEI-C12). It forms a solid-state complex that is water-insoluble when the number of complexable amino functions is equal to the number of carboxylic acid groups [128]. Its structure is smectic A-like. The same complex forms nanoparticles when the polymer is used in an excess of 50% [129]. The particles exhibit hydrodynamic diameters in the range of 80-150 nm, which depend on the preparation conditions, i.e., the particle formation is kinetically controlled. Each particle consists of a relatively compact core surrounded by a diffuse corona. PEI-C12 forms the core, while non-complexed PEI acts as a cationic-active dispersing agent. It was found that the nanoparticles show high zeta potentials (approximate to +40 mV) and are stable in NaCl solutions at concentrations of up to 0.3 mol l-1. The stabilization of the nanoparticles results from a combination of ionic and steric contributions. A variation of the pH value was used to activate the dissolution of the particles. 

In conclusion it was shown that the solid-state complexes formed by poly(L-arginine), poly(L-histidine) and poly(L-lysine) cations and retinoic acid can be prepared as films and nano-particles. The high content of retino-ate moieties, the absence of crystallinity and low particle sizes could make these complexes interesting as a new carrier for the delivery of retinoic acid, either transdermal or in body fluids. It may be speculated that supramolecu-lar structures such as the smectic A-like nano-particles of the tart-type pre-... 

Bis(pentametiiylcyclopentadienyl)actinide(IV) mono- and dialkyl complexes are readily prepared from Cp 2 Cl2. A rather large number of alkyl groups have been employed, and compounds of this class are generally prepared by metathesis (equation 59). In the solid state, complexes of formula Cp 2" n 2 adopt a pseudotetrahedral coordination geometry about the actinide metal. A neutron diffraction study of the thorium neopentyl complex Cp 2Th(CH2-t-Bu)2 also revealed agostic Th-H-C interactions with the q -CH bonds. ... 

Figure 22-22. Structure of (a) L-proline stationary phase and (b) A -(3,5-dinitrobone-zoyl)leucine amides. The right ORTEP diagram illustrates showing the numbering system depicting the conformations present in the solid state complex. (Reprinted from reference 96, with permission.)...

Storage Liquid, Compressed Gas, and Solid State (complex... 

Kunkely and Vogler reported on the excited state properties of [Cu(hfa)bta], with the absorption at 324 nm assigned to a spin-allowed Cu+ Jt bta MLCT transition. The solid state complex shows a broad emission band at 601 nm arising from MLCT. Besides, the photochemical behavior of this complex is in accordance with MLCT instead of LMCT. 

It was a long-standing puzzle in the 1930s that intense color was seen in crystals and solutions of weak stoichiometric (1 1) complexes (benzene (1) with iodine (I2), or naphthalene (2) with trinitrobenzene (TNB, 7)) and other similar systems. This intense color formed when the components are mixed in solution, and cocrystallized as stoichiometric solid-state complexes. These solutions and crystals showed, almost unchanged, the full optical absorption spectrum of the neutral components, plus an extra broad, intense absorption band with little or no vibrational structure one seemed to get something (color) for nothing (no change in other properties). 

Complex Formation Involving Calixarenes 7.1 Solid State Complexes with Neutral Molecules... 

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