Chelating ligands adducts

Cyanide binds to a series of Ni complexes with N302 chelate ligands, and EPR spectra of the adducts indicate quasi-axial symmetry with a g pattern typical of low-spin, six-coordinate complexes with axial elongation and with a 2Ay ground state. No direct spin interaction of the unpaired electron with the carbon atom of the cyanide takes place.70... 

Many 1,4-diazabutadiene adducts of dialkylzinc compounds show unusual reactivities (see also Section 2.06.10.7), such as the intramolecular electron transfer from zinc to the chelating ligand and the subsequent dimerization of these radicals.127 In solution, the carbon-carbon coupled dimer [MeZn(ButN=CHCH=NBut)2ZnMe] 71 is in equilibrium with its radical monomers (Scheme 56). Addition of potassium to a THF solution of the dimer produced cleanly 72, the first heteroleptic alkyldiamidozincate. 

The presence of water in the crystals can be explained by humid crystalization conditions and is proven by elemental analysis. The water adduct formation shows, that k 0, 0 -carboxylato ligands are hemilabile, chelating ligands, which can be easily displaced from one coordination site by a solvent. Thus, the carboxylato complexes 37a and 37b are equivalent to 16 VE fragments stabilized by the hemilabile carboxylato complexes. 

Four-coordinate, monomeric aluminium amides. Monomeric, four-coordinate aluminium amido derivatives are now quite numerous, yet none had been structurally characterized before 1980. They may be divided into two broad categories those which are Lewis base adducts and those in which four-coordination for aluminium is a result of complexation by a chelating ligand. 

The possibility of carrying out the type-programmed synthesis (preparation of different types of coordination compounds from the same ligands) is directly related to the problem discussed [10-12,14], On the basis of the data given above, it follows that both ICC and molecular adducts [Schemes (4.19), (4.24), and (4.34)] can be obtained from chelating ligands. Heteroaromatic ligands form [(4.13) and (4.15)] molecular and -complexes. 

The inert hydroxo-bridged species were also a product of (very fast) hydrolysis of p-cymene osmium complexes with glycinate, L-alaninate, a-aminobutyrate and p-alaninate. However, complexes with picolinate as the chelating ligand, [Os(r 6-/> cym)Cl(pic)] 8 and [Os(r 6-biph)Cl(pic)] 9, with pyridine as /V-donor and carboxy-late as O-donor, hydrolyzed with half-lives of 0.20 and 0.52 h (298 K), and aqua adduct pKa values (pk L value for solutions in D20) of 6.67 and 6.33, respectively. Complexes 8 and 9 were cytotoxic towards A2780 human ovarian cancer cells, with IC50 values of 8 and 4.2 pM, respectively [64],... 

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