Ligand structures characterization

Ligands, structurally characterized by an atropisomeric backbone consisting of two interconnected five-membered heteroaromatic units were initially developed by Sannicolo et al. in 1996 (Figure 2). The authors recognized the oxidation potential as a good tool to evaluate the electronic availability of the phosphorous atom in this series of biheteroaromatic diphosphines (00JOC8340). The increasing order of oxidative potential determined by voltametry is N-Me-2-BlNP... 

A number of transition-metal complexes of RNSO ligands have been structurally characterized. Three bonding modes, r(A,5), o-(5)-trigonal and o (5 )-pyramidal, have been observed (Scheme 9.1). Side-on (N,S) coordination is favoured by electron-rich (et or j °) metal centers, while the ff(S)-trigonal mode is preferred for less electron-rich metal centres (or those with competitive strong r-acid co-ligands). As expected ti (N,S)... 

Returning briefly to CO2 as a ligand in addition to the various mono-C02 complexes referred to above, several bis(rj -CO2) transition-metal adducts are known, e.g. /ran -[Mo( ) -C02)2(PMe3)4] (5) and trans.mer-[Mo( 2-C02)2(PMc3)3(CNPr )].< 22 The first homo-bimetallic bridging-C02 complex has also been structurally characterized by X-ray analysis, viz. [(dppp)(CO)2Re(/x, j 0,0 j C)Re(CO)3(dppp)] (6) [dppp = l,3-bis(diphenyl-phosphino)propanc]. 0 3)... 

The complex 23 is the first X-ray structurally characterized metal coordination compound with a benzochalcogenazole ligand in which chalcogen behaves as the ligating atom. 

A structurally characterized gold complex with a C5HPh4 ligand Au(r C5HPh4)(PPh3) (46a) was reported [66], An unusual trinuclear cluster 46b derived therefrom was also characterized by X-ray structural analysis. 

The only structurally characterized derivative of a trisimido organophos-phonate anion is the spirocyclic tellurium(IV) complex (19), which is obtained from the interesting redox reaction between PhPCl2 and [Li2Te(N Bu)3 ] 2 [27]. The phosphorus(V)-centered ligands are generated by imide transfer from tellurium to the phosphorus(III) atoms with concomitant reduction of one-half of the tellurium in the Te(IV) reagent to elemental tellurium [27]. 

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