Imido-bridge-cluster

The other two classes of imido complex contain bridging imido ligands between two metal atoms as in [(/u,-NH)(/a-0) Mo-(0)[S2P(0Et)2l2 2], and between three metal atoms as in the iron cluster (37). 

Treatment of a suspension of Nd(NHPh)3(KCl)3 with trimethylalumi-num in hexane yielded the heteroleptic heterobimetallic cluster [Nd[(//.2-Me)2A/Me2]2(M3-NPh)(M2-Me)AlMe 2 in low yield (Fig. 29). The formation of the cyclic byproduct (Me2AlNHPh)3 was proven by means of NMR spectroscopy and X-ray crystallography [217]. The molecular structure of the Nd2Al6 dimer revealed the presence of a doubly deprotonated imido ligand bridging each a neodymium center and two aluminum atoms. 

This year has also seen a variety of new clusters and aggregates bridged by oxo, hydroxo and nitrogen ligands. Of particular interest are a pair of apparent imido clusters. But unsupported terminal imido ligands remain the field s araba fenice ... 

The reaction of the cross-bridged cyclam ligand H2CBC with divalent ytterbium precursors, YbR2 (solvent)2 (solvent = THF or Et20) produced a trinuclear, cationic 3-imido Yb(III) cluster (O Connor et al., 2006). The edifice is made up of three Yb(III)(CBC) units, arranged into a triangular... 

The trinuclear cluster (Pd3(/i-NPh)2(/r-NHPh)(PEt3)3]Cl, containing bridging imido and amido ligands was prepared from Pd(II) according to the reaction (11) ... 

The promoting role of halides in the isocyanate-producing reaction was ascribed to their ability to assume a bridging position in the cluster, which is likely to weaken one of the N-Ru bonds, so rendering the imido fragment more likely to attack a... 

Notice that in this complex, where one imido group is replaced by a CO (2 e donor) with respect to compound 1, a third Fe-Fe bond is present. A tetranuclear cluster, Fe4(C0)8(p4-NEt)(p4-0NEt) was also obtained in very low yield. This is a rare example of an imido ligand bridging four metal atoms [58]. Moreover, even the p4 coordination of the EtNO ligand is very unusual. 

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