Donor atom sets

The influence of geometry and donor atom set on the spin state of five coordinate cobalt(II) and nickel(II). L. Sacconi, Coord. Chem. Rev., 1972, 8, 351-367 (117). 

Upper limit to Value of R(LT) corresponds to incomplete HS - LS transformation Donor atom set of central Fe atom, the only one showing a spin-state transition Two crystallographically independent iron(III) atoms involved, only one showing a spin-state transition... 

A series of mixed-ligand thiosalicylato complexes of the type PtL(PPh3)Y2] (Y2 = thiosalicylate L = pyridine, 4-methylpyridine, picolinic acid hydrazide, imidazole) have been prepared by the reaction of [PtCl2(COD)] with PPh3, thiosalicylic acid, and A-donor ligand in MeOH solution.375 The X-ray structure of the pyridine derivative (162) was determined, the first example of where a platinum atom is coordinated to a N, O, P, and S donor atom set. 

This review covers the coordination chemistry of technetium(V) and-to some extent-rhenium(V). In this survey, the complexes are arranged according to donor-atom sets in the coordination sphere. 

The comparison of Fe(III) spin transition systems with those of other metal ions reveals the greater variety of chromophores for which spin crossover is observed in iron(III). This is reflected in a generally more diverse coordination environment as well as a far broader range of donor atom sets. For six-coordinate systems the spin crossover generally involves an S=l/2<->S=5/2 change, whereas for five-coordinate materials an intermediate (quartet) spin state is involved in S=l/2<->S=3/2 transitions. There is just one report of such a transition in a six-coordinate system and that is considerably distorted [126]. 

Starting from complex (366) or (367) it is possible to produce a number of different complexes containing from zero to four imine linkages by means of reduction or oxidation reactions (Scheme 37).2639 In these redox reactions the Ni donor atom set remains intact, thus... 

Bidentate Schiff bases have been among those most used in preparing metal complexes. In the following subsections we shall describe the potentially bidentate ligands according to their donor atom set. 

Table 5 Some Geometrical Parameters of Potentially Bidentate Schiff Bases Having an N,N Donor Atom Set ... 

Table Typical Tridentate Schiff Bases with Different Donor Atom Sets...

Applications in the Nuclear Fuel Cycle and Radiopharmacy Table 21 Effect of Donor Atom Set on Tcv Complex Type... 

The number of tridentate ligands meeting the identification criteria is small. These ligands exhibit S3, S2N, or S2C donor atom sets and are summarized in Scheme 1. 

The notations, S3—H2, RS3—H, and so on are introduced in order to indicate donor atom sets and to serve as reading help . They are not to be confused with, for example, trisulfane HSSSH. 

The ligands with S2C donor atom sets have been found only in complexes and cannot be isolated in the free state. Sodium amalgam reduction of mononuclear [Ni(S4C3Me2)J leads to removal of benzenedithiolate and formation of trinuclear [Ni(p-S2C3Me2)]3 (Eq. 1) (10). The trinuclear complex shows cleavage and insertion reactions of interest as CO dehydrogenase model reactions (see below). Tetrahydrofurane = THF. 

---