Binuclear ligands systems

Ort/io-substituted TPP derivatives have been used as binuclear ligand systems by choosing suitable substituents on the phenyl rings. For example, treatment of a,a,a,a-H2(TAn,PP) 129 with maleic anhydride gave the tetrakis(o-maleamoylphenyl)porphyrin... 

Rh4Cl). The two binuclear Rh2 CN(CH2)3NC)3+ units have approximately eclipsed ligand systems but are nearly perfectly staggered with respect to each other. The Rh -Rh distance between the binuclear units is 2.775 A and within the binuclear units Rh-Rh is 2.932 and 2.923 A. Bond orders of 1 are proposed for these bonds, giving effectively a Rh(l)Rh(II)Rh(II)Rh(I) chain (357). 

In the following section we will concentrate on the most important classes of compounds which have been studied with the dimethylsilyl-bis(cyclopentadienyl) ligand system (30). In Scheme 14, five different types of complexes are portrayed, showing two principally different coordination modes of type 30 connection of two metal centres in binuclear units (type 38, 39 and 40) and chelation of one metal centre in mononuclear complexes (type 41 and 42). 

Modification of ligand systems in azine complexes was studied for the example of reactions (3.223) of r 6-coordinated 2,4,6-collidinechromiumtricarbonyl 773 (L = CO) [294] and its monotriphenylphosphine derivative 773 (L = PPh3) [492] with Lewis acids (AlBr3, SnCl4 TiCl4), leading to binuclear structures 774 ... 

In general, the preparation of binuclear complexes with the features in which we are interested is hampered by the poor solubility of the intermediates. Furthermore, there are only a few ligands which will enhance the donor properties of, e.g., Pt(II). This led us to investigate a new ligand system, propene-thione-thiol (PTT) or dithiomalonaldehyde,... 

The h-p and the a-b electron pairs are triplet coupled (S = 1) in the determinants that cause spin polarization in the ligands. Which values can be assigned to the total spin by coupling the two S = 1 electron pairs Are aU spin states relevant to the binuclear Cu + system under study ... 

H2 or O2 from water in the presence of a sacrificial reductant or oxidant employ a mthenium complex, typically [Ru(bipy)2], as the photon absorber (96,97). A series of mixed binuclear mthenium complexes having a variety of bridging ligands have been the subject of numerous studies into the nature of bimolecular electron-transfer reactions and have been extensively reviewed (99—102). The first example of this system, reported in 1969 (103), is the Creutz-Taube complex [35599-57-6] [Ru2(pyz)(NH3. 

A similar type of oxygen complex has been observed during the oxidation of [Con(CN) s]-3 but it was not possible to show that this species was formed in the initial reaction step since with this system, as with the cobaloxime(II) system, the 1 1 adduct apparently reacts very rapidly with another molecule of pentacyanocobaltate(II) to form a diamagnetic binuclear complex with a bridging peroxide ligand 116). It appears that in the Bi2-system the bulk of the corrin ring does not allow formation of the diamagnetic binuclear complex. 

Mono and binuclear platinum(II) complexes with diphosphines have been reported as catalysts in the hydroformylation reaction. Dppp and related diphosphines are used as ligands in platinum/Sn systems for the hydroformylation of different substrates.99-107... 

Some representative co-facial systems. The series (138)—(140) of mixed thiaaza donor ligands have been synthesized and all three have been shown to form binuclear complexes with transition metal ions (Lehn, 1980). In these, each metal ion is associated with one cyclic subunit as shown in (141) for (138). Complexes containing two Cu(n) ions or two Cu(i) ions have been obtained with each of (138)-(140) while (139), the... 

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