DMF molecules

Fig. 13 Parallel a and perpendicular b views of the 2D Pc sheet arrangement in 26 solvate DMF molecules are omitted for clarity...

Monte Carlo simulations were carried out to determine the free energy curve for the reaction in solution. The simulations were executed for the solute surrounded by 250 water molecules (or 180 DMF molecules) in the isothermal-isobaric ensemble at 25 °C and 1 atm, including periodic boundary conditions. As a consequence, the Gibbs free energy is obtained in this case. There is sufficient solvent to adequately represent the bulk participation in the chemical reaction. 

As mentioned above, for the simulation in dimethylformamide (DMF) of the same reaction [53], the parameters for the substrate were not changed from the parametrization in water. For DMF the parameters were adopted from the OPLS parametrization of the pure liquid. The transferability was tested in part by performing a Monte Carlo simulation for CT plus 128 DMF molecules and evaluating the heat of solution for the chloride ion. The obtained value compares favorably with the experimental estimate. It is important to remark here that when potentials are used to simulate different solutions to the ones used in the parametrization process, they no longer are "effective" potentials. This fact becomes more evident in the simulation of solutions of small ions with localized charge that polarizes the neighboring solvent molecules. In this case it is convenient to consider the n-body corrections. 

X-Ray investigation of the thiazolo[3,2-A][l,2,4]triazine compound 61 <2001H(55)2189> showed that this compound in the crystal phase exists as a solvate with dimethylformamide (DMF), the amide group is coplanar to the benzene ring (the respective torsion angles are below 4°), and intermolecular hydrogen bonds with the DMF molecules can be found. 

The polyhedron around La(III) in La(Py0)8(C104)3 has been described as a square antiprism, highly distorted toward that of the cube 149). Distorted square antiprismatic geometry has also been found in Eu(thd)3(DMF)2 283). In this complex, two of the thd moieties form one square face, and one thd and two DMF molecules form the other square face. The DMF molecules occupy cis positions on the square face. As in the case of Eu(thd)3 DMSO 283), Eu(thd)3(DMF)2 also shows two nonequivalent conformations in the same unit cell. 

Figs. 12 and 13 show the crystal structure of 6-Gd. Four of the linear POM-catalyst dicarboxylic acid units, 5, are linked by di-lanthanide paddle wheel junctions (Fig. 12) into the open-framework material 96). Fig. 13 shows the large channels in 6-Gd. These are filled with dimethylformamide (DMF) molecules that are hard to remove (the boiling point of DMF at 1.0 atmosphere — 151 °C). Thus while the solvent-accessible internal volume of 6-Gd is 50.5% of the crystal... 

Fig. 13. The structure of 6-Gd along the 100) direction showing the large channels (cross-section = ca. 28 x 20 A) pores. (H atoms and DMF molecules omitted for clarity.)...

DMF, and Nbl jSDMF have been shown to involve O-bonded DMF molecules by i.r. studies. The latter compound may be constituted as [Nb-(DMF)g]l4 since no bands attributable to Nb—I were observed, and this formulation is supported by preliminary conductance data in DMF solution. E.s.r. studies of NbCl4,2L complexes (L = DMF, DMA, THA, dioxan, dimethoxyethane, hexamethylphosphoramide, or AA -diethylformamide) indicate that they adopt a trans-octahedral geometry. 

Fig. 47. X-Ray structure of the hydrogen-bonded, ribbon-like species formed by self-assembly of the self-complementary component 168. In the schematic representation (right) the two DMF molecules contained in each cavity between the octyl chains are omitted [9.122].

The structural characterization of a mononuclear Eu-calix[6]arene complex reveals a more unusual complexation mode. In Eu(H4LXOHXDMF)6 (H6L = p-tm-butylcalix[6]arene Table 13) the Eu cation is placed outside the cavity forming only one monodentate bond to the calixarene ligand [193]. Six DMF molecules and most likely a hydroxyl group accomplish 8-coordination. The smaller sized calix[4]arene [194] and ether-extended bis(homooxa)-p-tert-... 

Figure 11.13. (a) Crystal structure of two [Ag3(7)2]3+ units linked by two Ag(I) atoms through Ag-N and Ag-S coordination to give a [Ag7(7)4]7+ unit (b) [Ag7(7)4]7+ tube with inclusion of two DMF molecules and two perchlorate anions (c) schematic drawing of the tube (d) [Ag7(7)4]7+ tubes linked by four-coordinate silver atoms to form an infinite ID chain. The hydrogen atoms, solvent molecules, and anions have been omitted for clarity. 

Channel structure of MOF-75 (a) ball-and-stick representation of inorganic SBU (b) SBUs connected by thiophene links. The DMF molecules and nitrate ions have been omitted for clarity. From N. L. Rosi, J. Kim, M. Eddaoudi,... 

Within the cage M8[Ti4(L21)4] (M = Li+, Na+ or K+) four counterions are bound to the internal oxygen atoms of the titanium tris(catecholate) units together with three DMF molecules per cation. Those counterions could be exchanged successively with primary ammonium ions as shown in Fig. 18. This exchange could be monitored by hi NMR spectroscopy, e.g. for the Lig[Ti4(L21)4] complex [139]. 

The dimetallic complexes with p-/-butylcalix[8]arene containing DMF molecules, [Ln2(H2butCx[8])(DMF)5]-(DMF)4 are efflorescent and exhibit polymorphism associated... 

In sharp contrast the DPM complexes of Eu with attached pyridine, the corresponding [Eu(DPM)3 (DMF)2] complex is square antiprismatic with the two DMF molecules in cis positions on the same square face [69], the three chelate rings span the S edges. It is obvious from this that any extrapolation of structures from solid to solution must be done with extreme caution. 

The existence of a tetracyanocobaltate(II) ion in aqueous solution has been inferred from studies at high dilution and a brown polymeric complex of composition K2[Co(CN)4] has been isolated from solutions of [Co(SCN)2] and KCN in ammonia.20 Recently, the monomeric air-sensitive complex [(PPh3)2N]2[Co(CN)4] DMF has been crystallized from DMF solution.29 The complex is essentially square planar but does feature a very weak axial interaction to a neighbouring DMF molecule (Co—O separation 264 pm). The [Co(CN)4]2 anion appears to be the sole example of a square-planar low-spin (ji = 2.15 BM) cobalt(II) complex containing solely unidentate ligands. 

Figure 80. Molecular structure of the ID compound [TpFe (CN)3] [Mn (dmf)2]2( l-OTs)2] = (only the O atoms of the dmf molecules are illustrated for clarity).

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