Tripodal ligand

Classic A/-heterocychc ligands, eg, bipyridyl (bipy), terpyridyl, imidazole, pyrazine, phenanthroline, piperazine (including alkyl- and aryl-substituted derivatives), and polypyrazol-l-yl-borates (bis, tris, and tetra), have all been found to coordinate Th(IV) chlorides, perchlorates, and nitrates. The tripodal hydrotris(pyrazolyl)borates, HBPz, have been used to stabilize organometaHic complexes (31). Bis-porphyrin Th(IV) "sandwich" complexes have been... 

Other 5-coordinate Co compounds which have been characterized include [CoBr- N(C2H4NMe2)3 ]+, which is high-spin with 3 unpaired electrons and is trigonal bipyra-midal (imposed by the tripod ligand), and... 

Cirunwald-Winstein analysis, 1,505 thiocyanates, 3, 729 thiourea, 3, 755 tricyanomethides, 3, 709 triethylenetetramine, 3, 722 tripod ligands tetradentate, 3,734... 

With tripodal tris(diphenylphosphinito)fluoroborate [FB(OPPh2)3] ligands and gold(l) complexes two structurally related, completely inorganic cages 81 and 82 are known (Fig. 22) [118, 119]. 

Besides such intermolecular stabilized compounds, intramolecular stabilized compounds have also been reported. Rettig et al. described the synthesis of phosphine-stabilized Al—N monomers by using a tripodal ligand [101]. More recently, Raston et al. reported on the synthesis of compounds of the type [H2A1E(H)R]2, containing only weak Al—H bridges [102]. 

Iron(II) complex of tris(N -tert-butylurea-ylato)-N-ethylene]aminato activates dioxygen at room temperature to afford an iron(III) complex containing a single terminal oxo ligand. X-ray structures show that the three urea molecules act as a tridentate N,N,N-hgand [52]. The tripodal ligand was also used to synthesise complexes of cobalt, iron or zinc with terminal hydroxo ligands (Scheme 8) [53]. 

Figure 3. The molecular structure of the oxygen tripod ligand [Cp 3Cr3(jX3-0)(p2-OH)3) Q ...

Casares, J.A., Espinet, P., Hernando, R., Iturbe, G., Villafane, F., Ellis, D.D. and Orpen, A.G. (1997) Poly(2-pyridyl) phosphines, PPynPh3 (n = 2, 3), and Their P-Substituted Derivatives as Tripodal Ligands in Molybdenum(O) Carbonyl Complexes. Inorganic Chemistry, 36(1), 44-49. 

By far the most studied pyrazole-containing ligand is the symmetrical monoanionic tripod hydridotrispyrazolylborate, Tp (3). Substituents introduced at each of the 3-, 4- or 5-positions (3,5-Me2Tp108, 3-z Pr,4-BrTp109) have led to a number of sterically encumbered threefold symmetric complexes and some remarkable Co coordination chemistry has ensued. Hydride substitution at the B atom is also possible by organic groups such as /z-bromophcnyl, which enables further functionalization of the ligand.110... 

Complexes with polypyrazolylborates and related tripodal ligands 300... 

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