3- dinickel

Dinickel trioxide Nickel dioxide Nickel monoxide Nickel subsulphide Nickel sulphide Potassium chromate Potassium dichromate... 

The side-on structure (3) has been established in two dinickel complexes which have very complicated structures involving lithium atoms also in association with the bridging It also... 

AGE965, 86AGE1099, 880M2316). Species /x-h h -(2-benzyl-l,3,4,5-tetramethyl-2,3-dihydro-l,3-diborolyl)(i7 -allyl)(i7" -l,5-hexadiene)dinickel and /x-i7 i7 -[2-(2,4,6-trimethylbenzyl)-l,3,4,5-tetramethyl-2,3-dihydro-l,3-diborolyl](i7 -allyl)(i7" -l,5-hexadiene)dinickel serve as representative tripledecker complexes (01ZN(B)73). 

In contrast to the abundance of Fe-proteins, there are only six known nickel-containing enzymes hydrogenase, CO dehydrogenase (CODA), acetyl-CoA synthase (ACS), superoxide dismutase, urease, and S-methyl-CoM methylreductase. Among these enzymes, it exists in very diverse environments, including a dinickel site (urease), a Ni-Fe heterobinuclear site (hydrogenase), a Ni-Fe4S4 heterometallic... 

Template condensation reactions of the nickel(II) complex of 3,7-bis(2-aminoethyl)-l,3,5,7-tetraazabicyclo[3.3.1]nonane with formaldehyde and the appropriate primary diamines such as ethylenediamine, 1,4-butanediamine, and p-xylenediamine yield dinickel(II) complexes of bis-heptaazamacrocyclic ligands (716)-(718). Similarly, the dinuclear Ni11 complexes (719) and (720) were prepared by using [Ni(2,3,2-tet)](C104)2, formaldehyde, and NH2—(CH2)ra—NH2 ( = 2, 3, 4, 5, 6, 10) or melamine, respectively. 

The denticity of the ligand compartments in bis(macrocyclic) Ni11 complexes can be increased by adding donor substituents to the macrocycles. For example, type (723) dinickel(II) complexes... 

Pyrazolato-bridged bis(tacn) ligands and their dinickel complexes are mentioned in Sections 6.3.4.12.6 and 6.3.4.12.7. 

In most cases the Ni11 ions are low spin and in square planar coordination environment. Dinickel(II) complexes [Ni2L(pyrazolate)] of dinucleating ligands like (725) and dinickel complexes such as (726) feature two nearly reversible electrode processes at very negative potential,... 

Various dinickel(II) complexes related to (724d) but with a phenolate bridging moiety, type (724e), have been investigated. To illustrate the great variety, (729) and (730) are depicted as examples.1883 1884... 

The flexible ligand (731) forms stable dinickel(II) complexes both in solution and in the solid state. The crystal structure of [Ni2(731)Cl3] reveals the bridging phenolato-O, a secondary Cl bridge, and two terminal Cl ligands, i.e., six-coordinate metal ions.1885... 

Attempts have been made to exploit the intrinsic C2 symmetry of the phenolate-based dinickel core in enantioselective catalytic reactions. Therefore, enantiomerically pure C2-symmetric ligands such as (736a) and the corresponding dinickel systems (736b) have been prepared ( Equation (27)),1890 and (736b) was tested in the epoxidation of unfunctionalized alkenes with sodium hypochlorite as the oxidant. The catalytic reaction was found to be highly pH dependent with an optimum at a pH of 9. While the complex is catalytically active, significant enantioselectivity was not achieved. 

DinickelQI) complexes of general type (781) macrocycles have been studied in detail since the early 1990s.1952-1 (782) is the most prominent scaffold employed, and the structures of its dinickel(II)... 

Thiolate-bridged dinickel complexes and, in particular, heterobimetallic Ni/Fe complexes have attracted much interest as model systems for the hydrogenase enzymes. A review covering this... 

Type (820) dinickel complexes offer the opportunity of substrate binding within the bimetallic pocket, and highly preorganized complexes of this type have also been employed as model systems for the urease metalloenzyme (see Section 6.3.4.12.7). The Ni—Ni separation in type (820) complexes can be... 

In the case of macrocyclic tacn side arms, stability constants of type (820) dinickel complexes are considerably higher and six-coordination can be achieved due to the binding of additional coligands, either at both Ni11 (in (828))2031 or at only one of them (in (829)).2082... 

Unsymmetrical compartmental pyrazole ligands with different chelating side arms in the 3- and 5-positions have been developed for the controlled synthesis of unsymmetric dinickel(II)... 

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