Coordination compounds square-planar

Thus, the crystal structure of the copper compound obtained from Cu(OAc)2 H2O and the ligand BSI (Fig. 9, Ri = SPr and R2 = Bu ) in methanol confirms the formation of a monomeric, four-coordinate, distorted square planar Cu(II) complex (Fig. 10). It should be noted that a complex with the very same (chiral) ligand framework was already published almost fifty years ago by Lions and Martin (75). 

Gold Compounds. The chemistry of nonmetallic gold is predominandy that of Au(I) and Au(III) compounds and complexes. In the former, coordination number two and linear stereochemistry are most common. The majority of known Au(III) compounds are four coordinate and have square planar configurations. In both of these common oxidation states, gold preferably bonds to large polarizable ligands and, therefore, is termed a class b metal or soft acid. 

Simple nickel salts form ammine and other coordination complexes (see Coordination compounds). The octahedral configuration, in which nickel has a coordination number (CN) of 6, is the most common stmctural form. The square-planar and tetrahedral configurations (11), iu which nickel has a coordination number of 4, are less common. Generally, the latter group tends to be reddish brown. The 5-coordinate square pyramid configuration is also quite common. These materials tend to be darker in color and mostiy green (12). 

The most common oxidatiou states and corresponding electronic configurations of rhodium are +1 which is usually square planar although some five coordinate complexes are known, and +3 (t7 ) which is usually octahedral. Dimeric rhodium carboxylates are +2 (t/) complexes. Compounds iu oxidatiou states —1 to +6 (t5 ) exist. Significant iudustrial appHcatious iuclude rhodium-catalyzed carbouylatiou of methanol to acetic acid and acetic anhydride, and hydroformylation of propene to -butyraldehyde. Enantioselective catalytic reduction has also been demonstrated. 

The most common oxidation states and corresponding electronic configurations of platiaum are +2 which is square planar, and +4 which is octahedral. Compounds in oxidation states between 0 and +6 [t) exist. Platiaum hydrosilation catalysts are used in the manufacture of siHcone polymers. Several platiaum coordination compounds are important chemotherapeutic agents used for the treatment of cancer. 

Since X-ray determinations of structure were too time-consuming to be widely used in the l9-2()s and 1940s and. in addition, square-planar geometry was a comparative rarity, any paramagnetic compound, which on the basis of stoichiometry appeared to be 4-coordinate, was presumed to be tetrahedral. 

Compound [PtCl( Bu2PCMe2CH2)2l reacts with pyrazole or 3,5-dimethyl-pyrazole in the presence of sodium hydroxide to form 242 (R = H, Me) [84ICA (82)L9]. The chelate ring is not planar in this case, and the trans strucmre of the pyrazolate derivative was demonstrated. Tlie four-coordinated platinum atoms are characterized by a distorted square-planar coordination. 

In synthesis (b), the initial product is a 5-coordinate (sp) iridium(III) hydride complex, which is rapidly oxidized in solution to the planar iridium(II) complex. Both of the compounds are paramagnetic with one unpaired electron, as expected for square planar d7 complexes. 

There is significant metal-metal bonding in the platinum compound, whose geometry involves a square of platinum atoms another important difference is that the coordination geometry is square planar in palladium acetate but octahedral in the platinum analogue. Different oligomers exist in solution, broken down by adduct formation. Palladium(II) acetate may be obtained as brown crystals from the following reaction [65] ... 

Spot tests, 1, 552 Square antiprisms dodecahedra, cubes and, 1, 84 eight-coordinate compounds, 1,83 repulsion energy coefficients, 1, 33, 34 Square planar complexes, 1,191, 204 structure, 1, 37 Square pyramids five-coordinate compounds, 1,39 repulsion energy coefficients. 1,34 Squares... 

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