Tris methane, structure

The first copper(I) complex of tris(hydroxymethyl)phosphine ((760) tetrahedral) has been reported by Samuelson and co-workers. This group addressed the question of anion-controlled nuclearity and metal-metal distances in copper(I)-bis(diphenylphosphino)methane complexes, and in this endeavor they reported the structures of complexes (761) (Cu-Cu separation 3.005-3.128 A), (762) (Cu-Cu separation 3.165 A) and (763) (tetrahedral Cu-Cu 3.293 A). 6 They synthesized and provided structural evidence of oxy anion- encapsulated copper(I) complexes of this ligand. The complexes (764) (distorted tetrahedral Cu-Cu 3.143 A), (765) (distorted tetrahedral Cu-Cu 3.424A), (766) (distorted trigonal Cu-Cu 3.170A), and (767) (Cu-Cu 3.032-3.077A) were reported. They studied solid-state emission spectra of these complexes.567 During this pursuit they... 

The tris(pyrazolyl)borate and tris(pyrazolyl)methane systems represent an important class of tridentates which lead to spin crossover behaviour in iron(II) but they belong to a totally different structural category and are... 

Although the poly(pyrazolyl)borate complexes of iron(II) have been well known for many years, [1] it is only recently that the complexes with the tris(l-pyrazolylmethane ligand, HC(pz)3, [45-48] have been studied in detail. It should be noted that poly(pyrazolyl)methane ligands, such as the tris(l-pyrazolylmethane ligand, are neutral, whereas the poly(pyrazolyl)bo-rate ligands, such as the tris(l-pyrazolyl)borate ligand, HB(pz)3", are monoanions. As a consequence, the metal(II) poly(pyrazolyl)methane complexes are dications and often have quite different properties from those of the analogous metal(II) poly(pyrazolyl)borate molecular complexes. But, in spite of these differences there are often very close structural similarities between the dicationic complexes and the neutral complexes. Therefore the study of the pyrazolylmethane complexes will parallel that of the borate complexes discussed above. 

Compounds of structure 5 have yet to be realized but terminal tridentates of the tris(pyrazolyl)hydridoborate [49], tris(pyrazolyl)methane [50] or tri-azacyclononane [5] types could be contemplated. 

THAM, or TRIS, is tris-(hydroxymethyl)amino methane. Its structure is (HOCH2)3CNH2. It is a base because it contains the -NH2 group, which accepts a hydrogen ion to form -NH3+. It is useful as a primary standard because it possesses all the qualities sought in a primary standard, as discussed in Section 4.6.2. 

The structures of the bis-ligand iron(II) complexes of the tripodal ligands tiis(pyiidin-2-yl)methane and tris(pyridin-2-yl)phosphine oxide have been determined." " The tetradentate tripodal ligand... 

The structures of the bis-ligand iron(II) complexes of the tripodal ligands tris(pyrazol-l-yl)methane and bis(pyrazol-l-yl)(pyridin-2-yl)methane have been determined the former is a spin cross-over complex." " Polybis(pyrazolateiiron(II) has a ID chain structure with the Fe " " ions doubly bridged by pyrazolates the Fe + ions (-S = 2) are weakly antiferromagnetically coupled. ... 

The potential of the negative chemical-ionization (n.c.i.) technique for obtaining valuable structural information on very small samples of underivatized oligosaccharides has been demonstrated.200 The n.c.i. spectra of several mono-, di-, tri-, and tetra-saccharides were recorded, using methane as the reagent gas, and direct-probe insertion of the samples into the ion source.201 Fairly intense, molecular ions, M-, were observed in each case. A small number of fragment ions were also observed, but could not be interpreted. Use of dichlorodifluoro-... 

Reaction of the bis(diphenylphosphino)methane (dppm) complex PdPt-(yi-dppm)2Cl2 (132) with carbonylate anions affords several tri- and tetranuclear clusters. Reactions are outlined in Scheme 7. Treatment of 132 with 2 mol equivalents of [Fe(CO)3(NO)] (796,797), [Co(CO)4] (196,198), or [Mn(CO)5] (196,197) results in the tetranuclear spiked triangular clusters 133,134, or 135. Crystal structures on the dipalladium analogues of 134 and 135 have been reported (797,799). Grossel et al. (136) and Braunstein et al. (200) have independently reported that reaction of 132 with 1 mol equivalent of [Fe(CO)4]2 at ambient temperatures leads to an inseparable 1 1 mixture... 

It is important to realize that for any arrangement of more than two atoms the strain energy minimized structure does not have ideal (zero strain) distances and angles. This is demonstrated in the case of ethane (Fig. 2.2), where, due to the repulsion of the protons, the experimentally determined C-C distance in ethane of 1.532 A, which is well reproduced by empirical force field calculations, is slightly longer than the ideal C-C separation of 1.523 A used in the MM2 force field1. Further examples are presented in Table 2.1. With increasing substitution of the carbon atoms the C-C separation increases up to 1.611 A in tris(t-butyl)methane. 

Xenon difluoride reacts also with some halosubstituted alkanes18,19 at room temperature in chloroform, carbon tetrachloride, dichloromethane or bromoform, and depending on the nature of the solvent used chloro or bromo derivatives are isolated with imidazo-(l,2-fr)-pyridazine18. Carbon tetrachloride reacts with xenon difluoride at 180°C, while room-temperature transformations are achieved when various catalysts [antimony trifluoride, tantalum(V) fluoride or silica dioxide] are used, whose structure also influences the product distribution20. Tris(fluorosulfonyl)methane gives a fluoro-substi-tuted product in its reaction with xenon difluoride in difluorodichloromethane21. 

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