Imide clusters

Lee, S.C. (2002) Iron-imide clusters and nitrogenase Abiological chemistry of biological relevance In Leigh, G. J. and Winterton, N. (eds) Modem Coordination Chemistry Royal Society of Chemistry, Cambridge, pp. 278-287. 

Iron-Imide Clusters and Nitrogenase A biological Chemistry of Biological Relevance ... 

Iron-Imide Clusters and Nitrogenase Abiological Chemistry of Biological Relevancel... 

When the self-assembly reaction is conducted in toluene, a different product distribution is obtained. Neutral cluster products are still formed in low yields however, terminal imide cluster 7 is now the predominant neutral species, with chlorocubane 5 virtually absent as judged by NMR spectroscopy. The... 

The major product obtained from the reaction of TeCU with (McsSijsN is determined by the stoichiometry. When approximately equimolar amounts of the two reagents in THF are used the dimeric cluster TceNs (stabilized by coordination to four TeCU molecules) is obtained in high yields (Section 5.2.8). When the same reaction is carried out in acetonitrile with a molar ratio of 2 1, followed by treatment of the product with AsFs in SO2, [Tc4N2Cl8][AsF6]2 is obtained Section The dication [Tc4N2Cl8] in this salt is the dimer of the hypothetical tellurium(IV) imide [Cl3Te-N=TeCl]. ... 

Heptagold heteronuclear cluster compounds X-ray crystallography, 39 371-373 Heptasulfur imide, 2 161-164 Herbicide-binding protein, 33 224 Heteroallenes, cycloaddition to iminoboianes, 31 161... 

In earlier work, no molecular structural data were available on mononuclear M amides, but this has changed markedly in the last three (and particularly last two) decades. Another significant development has been the use of the title compounds, and especially the homoleptic dimethylamides M(NMe2)3, as reagents, or synthons for the preparation of bridging binuclear imides 7 (Section 10.3) or cluster imides (e.g. 3 7) (Section 10.4), or Bi[N(SiMe3)2]3 as a precursor for atomic layer deposition.Heteroleptic amidometal chlorides have featured as precursors to cationic metal(III) amides (Section 10.2.4). 

Since the pirn and mpim molecules are quite large, any ab initio calculation including a cluster of metal atoms will necessarily be very tedious. Therefore, it is desirable to model the ligands by a subsystem which includes only the part that is primarily involved in the interaction with the copper surface. As mentioned in the introduction, data from XPS core level spectroscopy show that the nitrogen atom is the primary reaction site in the interaction between pirn and a copper surface, and that the effect of this interaction does not extend significantly into the benzene moiety of the pirn molecule. Therefore, we chose as a model system for pirn the molecule NH(CHO)2 (di-formimide, see Figure 1). As will be shown in the next section, the electronic structure of this model molecule has an electronic structure which very much resembles that of the imide part... 

Among other ruthenium catalysts, the cluster Ru3(CO),2 has been found to efficiently catalyze the N-alkylation of amides, imides, and lactams by alcohols. Acetamide can be converted into A-ethylacetamide with ethanol, according to... 

Mukhopadhyay et al. [98] studied the titanium electrodeposition on a Au(lll) substrate in the l-methyl-3-butyl-imidazolium bis(trifluoromethylsulfone) imide ([BmimJBTA) ionic liquids with 0.24 M TiCl at room temperature. It was found that TiCl is converted to TiCl in a first step, which is subsequently reduced to metallic Ti. Two-dimensional (2D) clusters form preferentially on the terraces in underpotential deposition range. At a potential of -1.8 V, a dense layer of three-dimensional (3D) clusters of titanium of 1-2 nm thickness is formed. The electrochemical reduction of tetravalent titanium species in hydrophobic 1-n-butyl-l-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP]TFSI) room-temperature ionic liquid was studied by Kayayana et al. [182]. It was found that the stepwise reduction from Ti(IV) to Ti(III) and probably Ti(II) in [BMP]TFSI containing TiBr without [BMP] Br. The potentiostatic cathodic reduction gave some deposits at 180°C. The reduction of Ti(rV) species at -2.3 V led to the deposition of some Ti compounds containing... 

This suggests that the water is weakly bound and can freely rotate in the polyimides, but is tightly bound or clustered in the polyamide-imides. 

The synthesis of the imidoiron cubane 4 and the possibility of cluster-bound imide ligands as intermediates during nitrogenase turnover has led us to a general exploration of weak-field iron-imide (Fe-NR) cluster chemistry. Our initial studies establish the existence of a rich reaction manifold that is readily accessible from simple iron(iii) precursors. A recent report from Fenske and co-workers describes additional synthetic routes to Fe-NR clusters,further demonstrating the generality of the chemistry. 

Our preliminary survey of Fe-NR cluster chemistry reveals strong parallels between imide and sulfide ligation on high-spin iron. The dinuclear, trinuclear, and tetranuclear geometries found in imidoiron clusters all have structural counterparts in fundamental biologically-relevant Fe-S cluster motifs (Figure... 

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