The electron distribution within a mesityl ligand bridging a cyclopentadienyliron fragment attached to the mesityl π system and a second metal fragment connected to the ipso carbon of the mesityl ring has been probed using a copper(I) halide as a component in [CpmFe (μ,η5 :η1-C6H2Me3)CuCl] (2) and its copper bromide derivative 3. This approach minimizes steric effects and allows for DFT calculations the results of which are in very good agreement with structural data. The calculations show a significant carbene character already for the bare phenyl anion as a result of electrostatic repulsion of the lone pair pushing the π electrons away from the ipso carbon towards the para carbon atom of the aromatic ring. π Coordination of a cyclopentadienyliron(II) fragment to the phenyl anion to form a hypothetical sandwich complex does not change this situation. The iron center rather follows the unsymmetric distribution of π charge with an unsymmetrical coordination to the π system. Coordination of a copper(I) chloride moiety to the phenyl anion or to the hypothetical π complex [CpFe(C6H5)] in both cases equally lowers that carbene character by attracting the lone pair of the ipso carbon and thus decreasing its repulsive influence on the π electrons.
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Routes of white phosphorus activation in the coordination sphere of the nickel complexes with different ligands are shown. The first route is based on the coordination of a P 4 molecule with the metal, resulting in the deformation of the P 4 tetrahedron without destruction. This case is characteristic of the NiX 2 L complexes, which are reduced at higher cathodic potentials (|E red | > 0.9 V) (X = BF 4 , Br, and Cl; L is bpy in DMF, MeCN, and acetone; 2,9 dimethyl 1,10 phenanthroline (phen) and PPh 3 in DMF and acetone). To cleave the P-P bonds in the P 4 molecule, this complex should be reduced on the electrode. The second route is the oxidation of white phosphorus in the coordination sphere of the Ni II complex. It occurs when the complex has a sufficiently high oxidizing ability and is reduced rather easily (|E red | < 0.9 V) (X = BF 4 , L is 1,1,1 tris(diphenylphosphinomethyl)ethane (triphos) in acetone; 1,1´,5,5´ bis[methylenedi(p phenylene)]di(3,7 diphenyl 1,5 diaza 3,7 diphosphacyclooctane) (n 2 p 2 ) in DMF; phen and PPh 3 in MeCN). The P 4 molecule opening is observed to form a new Ni I complex containing the (P 3 ) fragment, for example, [(triphos)Ni(P 3 )Ni(triphos)](BF 4 ) 2 .The electrochemical activation of reagents in processes involving organometallic compounds is very efficient. 1-4 This approach combines advantages of catalysis by metal complexes and activation by means of electrochemical electron transfer. The activation of white phosphorus is a practically important task because of the necessity to search for new routes of direct syntheses of organophos phorus compounds. Numerous reactions of P 4 tetrahedron transformation were described, which resulted in various polyphosphorus structures among which metal complexes with cyclic P 3 , P 5 , and P 6 ligands, 4 as well as the P 4 ligand, 5,6 seem to be most interesting. The P 4 molecule is activated due to the deformation of the P 4 tetrahedron and, as a consequence, the P-P bond length changes. In ultimate cases, these bonds can cleave to form new polyphosphorus structures. Until now, P 4 transformation was studied only by NMR spectroscopy, and very stable compounds were examined. Evidently, the more stable these structures, the more difficult is the preparation of related basis organophosphorus compounds, i.e., the main task of the elemental phosphorus chemistry is the direct transformation of phosphorus into organophosphorus compounds (OPC), excluding traditional steps of its chlo rination. At the same time, metal complexes with poly phosphorus ligands can possess a set of useful properties: semiconductivity, corrosion resistance, and others 7 and act as stable intermediates in various reactions, which are of independent interest.In this work, we attempted to estimate the reactivity of several nickel complexes with σ donor ligands toward white phosphorus using cyclic voltammetry (CV), pre parative electrolysis, and 31 P NMR spectroscopy. The nickel complexes were chosen, because they are catalysts of some reactions of white phosphorus functio...
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