Nickel complexes spectra

The first Ni Mossbauer spectrum of nickel in a bioinorganic compound with determinable EFG and isomer shift was reported for a nickel complex compound with planar [NiSJ core and considered as a model compound for hydrogenase. This Mossbauer spectrum from the formal Ni compound is presented in Fig. 7.16. The observed quadrupolar interaction can be understood in terms of ligand field theory. In this approach, the b g and levels (d y2 and d ) are not occupied which is expected to cause a large negative EFG contribution [32]. 

Fig. 7.16 Ni Mossbauer spectrum at 4.2 K of a nickel complex compound with planar [NiS4] core known as a model compound for hydrogenase (source Nio.gsCro.is (97% enriched) activated at Mainz Microtron) (from [32])...

Fig. 50 Phosphorus-31 CP/MAS spectrum of the nickel complex shown, which is immobilized on silica gel, recorded at a spinning rate of 4 kHz (lower spectrum) and HRMAS spectrum of an acetone suspension, recorded at a spinning rate of 2 kHz (upper spectrum)...

P.O.59 is a nickel complex which affords very dull yellowish shades of orange. The pigment was used to match deep to medium shades in the yellow and orange part of the spectrum for high grade industrial finishes, as well as for architectural paints. 

Isoelectronic with nickel carbonyl are the anions, Ni(CN)44- and Pd(CN)44-, which are obtained as their potassium salts by reduction of the corresponding cyanides of oxidation state +2 with potassium in liquid ammonia (32, 65, 186). The infrared spectrum of the nickel complex has been reported (67) to show only one band at 1985 cm-1, in the triple-bond... 

The nickel complexes, like those of monothio-jS-diketones, are diamagnetic. The Co11 complex of dithioacetylacetone is low-spin Ip., 2.35 BM) and square-planar the paramagnetic anisotropy and ESR spectrum indicate the ground-state configuration (dxy f (dxz)2 )2(dz2). 249,250 The complexes... 

Thus, the historical development of the chemistry of metallocorrolates until 1980 includes complexes with Cu2+, Ni2+, Pd2+, Fe3+, Co3+, Rh+, Mo5+ and Cr5+. The palladium complex has been isolated as its pyridinium salt since the neutral species was too unstable to be isolated or spectroscopically characterized [19]. The nickel complex was non-aromatic, with one of the potentially tautomeric hydrogens displaced from nitrogen to carbon in such a way as to interrupt the chromophore. In contrast the electronic spectrum of the paramagnetic copper complex is similar to those of the fully conjugated lV(21)-methyl derivatives [11],... 

Figure 12. (A) SIMS spectrum of a nickel complex showing characteristic ions (Cp = C5H5). (B) SIMS spectrum of the same complex in an alumina matrix.

The coordination of stable silylenes to metal complexes was also reported to produce transition metal silylenoids.40,41 Exposure of unsaturated silylene 16 to Ni(CO)4 resulted in the formation of the disilylene-substituted tetrahedral nickel complex 17 (Scheme 7.3).42,43 Similarly, mixing Ph PAuCI with decamethylsilico-cene 18 produced the silylgold complex 19.44 The 29 Si H NMR spectrum of 19 (8 78 ppm) revealed its silylenoid character. In addition to nickel and gold, other metals, including tungsten,41 platinum,45 iron,40 and ruthenium,46 have been utilized to form silylmetal complexes of stable silylenes. 

An x-ray crystal structure was reported for 250. Selected parameters are recorded in Table VIII. The nickel complex is similar to its platinum counterpart in that it has a nearly planar coordination geometry, and most of the parameters are very similar for the two. The most striking difference is in the M-C and M-P bond distances, differences that are comparable to those found in acyclic complexes.94 In the IR spectrum, the triple bond... 

Subjecting 2 or 3 to strongly acidic conditions (e.g. 1 M CF3CO2H or concentrated HQ) leads to rapid demetalation and the production of two isomeric free-base macrocycles 10 and 11 [11, 12]. The structure of 10 was conflrmed by its spectral properties and its remetalation to form the nickel complex 5. On the other hand, the structure of 11 was determined solely by its spectral properties. For instance, the NMR spectrum of 11 demonstrated the presence of a fully unsaturated system. Typical also was the presence of pyrrolic proton signals in the 6-7 ppm range of the NMR spectrum [12]. Compound 11 was very unstable... 

Nickel tetracarbonyl and nickel complexes with mixed carbonyl and alkylphosphine ligands in zeolite Y have been studied with EXAFS, NMR, and FTIR spectroscopies (85,240-242). The loading of Ni(CO>4 in dehydrated zeolite X can be as high as 28 wt%, corresponding to 2.75 Ni(CO>4 molecules per supercages. The IR spectrum of Ni(CO>4 was found to be affected by the cations inside the zeolite supercages. The spectrum of... 

The complex [Ni(2,3-Me2[14]-l,3-diene-l,4,8,lI-N4)] [ZnCU] is square planar and low-spin. The visible spectra show bands near 21.3 kK (characteristic of square planar nickel(II)), near 26.1 kK (due to the imine functions), and near 35.1 kK. The infrared spectra of all of the nickel complexes prepared show absorptions near 3195 and 1595 cm assignable to the N—H stretching vibration and to the symmetric imine vibration, respectively. A strong sharp band also occurs near 1210 cm and is characteristic of the a-diimine function. The NMR spectrum of the perchlorate complex in nitromethane shows a methyl singlet at 2.33 ppm. The ligand can be hydrogenated on nickel(II) with Raney nickel and hydrogen to produce the fully saturated macrocyclic complex [Ni(2,3-Me2[14]-ane-1,4,8,1 1-N4] ... 

In the IR-spectrum of the nickel complexes of CEP-PVP, we observe a band at 1640 which characterizes complexation of nitrogen atom and a decrease of intensity of the ban 1600cm which characterizes free pyridine ring. From these data and elemental analysis can assume that the structure of the nickel complexes with CEP-PVP might be illustrate follows ... 

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