Tris amine complexes

The [Cr(en)3]2+ and [Cr(pn)3]2+ salts have reflectance spectra (Table 11) resembling those of the hexaammines, and the six N donor atoms are assumed to complete tetragonally distorted octahedra around the metal. Stability constant measurements (Table 39) have shown that the ions [Cr(en)(aq)]2+ (vmax= 18 300 cm-1, e = 25 dm3 mol-1 cm-1) and [Cr(en)2(aq)]2+ (vma = 17 500 cm-1, e = 17 dm3 mol-1 cm-1) exist in aqueous solution, but that, as in the copper(II) system, the third ethylenediamine molecule is only weakly bound, and care is needed to prevent loss of en from tris(amine) complexes in the preparations. Several bis(amine) complexes, e.g. [CrBr2(en)2], have been isolated, and these are assigned trans structures because of IR spectral resemblances to the corresponding oopper(II) complexes. Since the spectrum of [Cr(S04)(en)2] also shows the presence of bidentate sulfate, this is assigned a trans octahedral structure with bridging anions. 

Chromium(II) complexes of bipyridyls, terpyridyl and the phenanthrolines have been discussed in Section 35.2.2.1. Complexes of the ligands 2-aminomethylpyridine (pic, 2-picolyl-amine) and 8-aminoquinoline (amq), which have one heterocyclic and one amino nitrogen donor atom, have been prepared by methods similar to those in Scheme 10. The bis(amine) complexes are typical high-spin, distorted octahedral complexes, and the mono(amine) complexes, from their antiferromagnetic behaviour and reflectance spectra, are six-coordinate, halide-bridged polymers (Table 15).103 No tris(amine) complexes could be prepared so the attempt to find spin isomeric systems in octahedral chromium(II) systems was unsuccessful ([Cr(en)3]X2 are high-spin and [Cr(bipy)3]X3 and [CrX2(bipy)2] low-spin). 

In the tris-pentafluorophenyl analog (TFPC), in contrast to other Co corroles, aromatic amines can substitute PPh3 to form six-coordinate trivalent bis(amine) complexes.788 Bis-chlorosulfon-ation of TFPC occurs regioselectively to give the 2,17-(pyrrole)-bis-chlorosulfonated derivative fully characterized as its triphenylphosphinecobalt(III) complex.789 The amphiphilic bis-sulfonic acid was also obtained. 

Gao, B. Wen, Y. Yang, Z. Huang, X. Liu, X. Feng X. (2008) Asymmetric ring opening of meso-Epoxides with aromatic amines catalyzed by a new proline-based N,N -dioxide-indium tris (triflate) complex,/t/v. Synth. Catal, 350 385- 390. 

C6Hi4Cl2N202Pt, Platinum(ll), cw-dichlorobis-(propanoneoxime)-, 34 82 C6Hi4Cl2N202Pt, Platinumfll), trani-dichloro-bis(propanoneoxime)-, 34 83 C6H18N4, tren, Tris(2-aminoethyl)amine, complex with copper(II), 34 138 CfiNNaOsW, Tungstate(O), pentacarbonylcyano-, sodium, 34 162... 

Both bis and tris ethylenediamine complexes have been described 12 the latter have been formulated [Sc(en)3]X3 (X=C1 or Br), this being supported by IR data. Heating in vacuum leads to formation of c -[ScX2(en)2]X. A number of complexes qf ScCl3 with primary and secondary amines, mainly aliphatic, have been prepared and their thermochemistry and IR spectroscopy studied.13-15 The compounds are ScCl3 (RR NH), where n = 1-4 and R = R = Me, Et, Pr, Bu or Pe or R = H and R1 - Et, Pr, Bu, Pe, phenyl, benzyl or 2-naphthyl. Further investigation would be necessary to establish the structural nature of these complexes. 

The circular dichroism (CD) spectra of optically active di-, tri-, and tetranuclear complexes of chromium(III) and cobalt(III) have been reported and used to establish the complexes absolute configurations (55 59, 111, 115, 116, 152-157). The changes in circular dichroism resulting from ion pairing have been studied for the tetranuclear hexol Co j(OH)2Co(NH,)4J, h+ and have been shown to be attributable to the vicinal effect of the chiral oxygen centers produced stereospecifically by the ion-pair formation (56). For a series of trinuclear cobalt (III) amine complexes, cis-Co(CN)2[(OH)2Co(N4)2 J3 +, it was shown that the main CD contributions due to the two chiral Co(OH)4(CN)2 and Co(N4)(OH)2 centers are additive (155). In the case of the related tetranuclear complex Co((OH)2Co(en)2J,< + this postulate of additivity of CD spectra proved unsatisfactory (57). 

All the linear triamines (27)-(31) are commerically available and there are others, such as 6,6-tri, which, as yet, do not appear to have been used in the preparation of coordination complexes. These linear polyamine ligands can coordinate in either meridional or facial topology and both bis(tri-amine) and mono(triamine) complexes are possible for octahedral central metal ions. 

Metal template syntheses of complexes incorporating the p-amino imine fragment have been introduced by Curtis as a result of his discovery that tris(l,2-diaminoethane)nickel(II) perchlorate reacted slowly with acetone to yield the macrocyclic complexes (40) and (41) (equation 8).81-83 In this macrocyclic structure the bridging group is diacetone amine imine, arising from the aldol condensation of two acetone molecules. This reaction is widely general, in the same way that the aldol reaction is, and can be applied to many types of amine complexes. The subject has been reviewed in detail with respect to macrocyclic complexes by Curtis.84... 

Hydroxylation of alkenes with m-chloroperbenzoic acid is efficiently catalysed by an Ni(II)-tris(2-pyridylmethyl)amine complex. The participation of an NiO+ (nickel-oxo) active species has been suggested.230... 

Figures 4 and 5 illustrate this point. The electronic lines in the facial tris(glycinato) complex are all more intense than the associated vibronic structure. This complex is fairly distant from centrosymmetry, because each amine group is nearly opposite a carboxylate. In the spectrum of the tris(ethylenediamine) complex, however, vibronic structure is more prominent. Though there is no actual inversion center, amines are nearly opposite amines, and the geometry is not far from centrosymmetric.

Another type of tri-imine complexes containing terpyridyl type ligands, in which the inner pyridyl ring has been replaced by an amino moiety, such as di-(2-pyridylmethyl)-amine (dpma) and di-(2-pyridylmethyl)methylamine (medpma) has been described... 

As a reductive condition, treatment of a,a,a-trichloroacetate (233) with a Cu1+-tris(pyridylmethyl)amine complex generates macrocyclic polyether (234) through initial SET from Cu1+ to trichloride, generation of a,a-dichloroacetate radical, 18-endo-trig ring closure, and abstraction of a chlorine atom from the a,a,a-trichloroacetate (233) by the formed carbon-centered radical as shown in eq. 3.92 [239]. 

Two reports included multidentate ligands as supports for amination chemistry. First, 4,4 -Di-tert-butyl-2,2 -bipyridyl ( Bu2bpy) stabilizes the thermally sensitive [LuR 3] unit, giving the [(tBu2bpy)Lu(R )3]- This tris(alkyl) complex readily reacts with Ph3COH, 2,6- Pr2C6H3NH2, 2,4,6-tBu3C6H2NH2, and N,N -dicyclohexylcarbodiimide to afford a variety of Lu(III) tris(alkoxide),... 

Most of the template syntheses of nonbenzenoid macrocycles originated with Curtis (39) and involve the condensation of metal-amine complexes with aliphatic carbonyl compounds, e.g., the reaction of acetone with tris(diaminoethane)nickel(II) perchlorate at ambient temperature leads to the isolation of three products, two of which may be represented as cts-XLIX and trans-L and the other is formed by a further interconversion of complex L in solution (39,143). With Cu(II) diaminoperchlorates, a mixture of cis and trans complexes analogous to XLIX and L is formed, but with Co(II) only the trans analog of L has been isolated. When ketones containing bulky groups are used, the reaction is much slower, e.g., there is only a small yield of LI from... 

---