Manganese and Rhenium

4 Manganese and Rhenium.- Reports of reactions in which the Cp ligand is implicated in the reactions is particularly common for Re. Lithiation of the ring is the initial product when CpRe(PPhj)(NO)H is treated with BuLi. Subsequent rearrangement gives Li[CpRe(PPh2)(NO)] 

Alternatively, treatment of (6) with CO leads to multiple ligand 

High oxidation state Cp complexes have been made by treating 

Discussions have appeared of the photochemistry of some rhenium phosphite complexes such as trans. msi. ReCl3py2[P(OEt3) ], 

ReCl4[P(OEt)3]2 and of the emission from [Re2Clgl, which seems to originate from the ss excited state of the eclipsed 54 

Sodium pentacarbonylmanganate(—i) displaces chlorine from 1,2-dichloro-tetrafluorocyclobutene, and fluorine from perfluororgrclopentene, to give (8) and (9a), respectively. 

Bromopentacarbonyl-manganese and -rhenium react readily with perfluoro-1-methylpropenylsilver to give good yields of the perfluoro-(l-methylpro-penyl)pentacarbonyl compounds (10).  

Photochemical reactions of Me3M-Mn(CO)6 (M = Si or Ge) with fluoro-olefins and acetylenes give low yields of products resulting from insertion into the M—Mn bond or, presumably, from decomposition of such products (see also p. 201), e.g. 

The fluorocarbon-bridged ligand (12a) reacts with decacarbonyl-diman-ganese and -dirhenium to give the novel dinuclear complexes M2(CO)g(L— L), (13a) and (13b) in each of these a symmetrically bonded (both and 

The bridged compounds rearrange when heated in xylene, and evidently also in the mass spectrometer, since (13a) and (14a) give identical mass spectra, and crystallographic results reveal that the manganese compound possesses structure (14), in which a Mn(CO)4 group has become inserted into 

The X -ray determined structure of [Mn2(M-CF2)2(CO)8] is reported. Photoreactions of [Re2(C0)j g] with ethylene, styrene or isoprene give various di- and tri- nuclear complexes Including structurally characterised [Re3 /i-o n2-C5H-j)(CO)3 3]. Allene and [Mn2(CO)3ol form three dlnuclear species including [Mn2( i-h ii7 -C3H4)(C0)3].  

Reaction of (CpMn(C0)2 THF)] with sulphur ylides (Me2N)RSO(CH2) produces Mn2( t-CH2)(C0)4CP2] or with ben2yl azide, [Mn2 it-CON(CH2Ph)N2 (CO)3Cp2), an intermediate in the formation of benzyl Isocyanate. 

Cocondensation of Re atoms with alkylbenzenes is a synthetic route to K-alkylidene compounds [Re2(n-H)2(fi-L)(n -arene)2] with L = CHAr, CMePh or CHCH2Ph ° cocondensation of Re atoms with benzene and trimethylphosphine forms [Re2 PMe3)4 n -C5Hg)2].  

Triply bonded [Re2X4(dppm)2 ] forms A-frame-like monoadducts with isocyanldes or with and also mixed carbonyl-isocyanide 

A number of complexes have been prepared from the electron-rich ligand 3,5-di(tert-butyl)-l,2,4-triphospholyl these include manganese carbonyl complexes and the manganocene, which has been structurally characterised. A paper explaining the facile silane dissociation in transition metal T -silane complexes Cp(CO)2M[p -H(SiH3 Cl )] (M = Mn, Tc and Re n = 1-3) (see, for example, 28) makes interesting reading.  

In a general paper the synthesis, structure and fluxionality of (p-diphenylsilyl-ene)(fulvalene)tetracarbonyldirhenium has been examined and a double Si-H activation is observed which led to the formation of the first fulvalene silylene, 

The following references are reported in title only form Synthesis, crystal 

An AT-ray crystal structure analysis has shown that the product of the reaction of CFs Rh(CO)6 with carbon disulphide is (0Q4ReS2CS[Re(CX ))4]2SCS2Re(C 0)4. The displaced trifluoromethyl groups were found as hexafluorothioacetone in the reaction mixture.  

Unexpected intensities of bands in the photoelectron spectra of CF3 Mn(CO)s and CHs Mn(CO)5 originally led to conclusions about the bonding in these compounds which were not in accord with other properties. It is now suggested that the enhanced intensities arise from the r-bonding ai orbital between the CFs (or CHs) and Mn.  

The reaction between NaRe(CO)s and tetrakis(trifluoromethyl)allene at low temperature has been reported to give (10). The chlorine n.q.r. spectrum of (11a) shows one of the lowest shifts in the series studied, in accord with the low electronegativity of the Mn(CO)s substituent.  

irradiation of manganese or rhenium carbonyl in tetrafluoroethylene at — 93 °C results in rapid polymer formation, and the presence of tetrafluoroethylene in other vinyl monomers also allows initiation of polymerization by these carbonyls. Addition of photochemically generated Mn(CO)4 to CaF4 to give the o-bonded radical species (OC)4Mn CF2 CF2 is suggested. 

MeaAs-CHF-CHF AsMea are mainly those of the major (racemic) isomer, but only for X = Br could the minor product be removed. Nevertheless, good n.m.r. spectra of all the complexes were obtained and were analysed in detail in terms of the preferred conformation of the five-membered rings [e.g. (16a, b)].i A similar reaction of Mn(CO)sI with MeaAs-CFa CHCFCFa AsMea gives (17), the n.m.r. spectra of which show equilibration of the six-membered chair conformations. 

Evidence has now appeared for dissociative loss of CO as a second primary process in the solution photolysis of Rej(CO),j,. This reaction is more important in Re iCO), than the corresponding reaction in Mh (CO),o. A FTIR photoacoustic investigation of the surface species resulting from photochemical reaction of Re2(C0),o with silica auid alumina has shown the formation of tricarbonyl species on the surface of both ox ides. 

An ESR study of the photolysis of a Re2(C0),o-Et3SiH system has been described and the rate constcuit for abstraction of H from EtjSiH by Re(CO)s measured. Photosubstitution of a carbonyl group in Re2(C0),o with P(OPh)3 gives four well-characterised products. The observed pattern of disubstituted cmd triply 

5-pentamethylcyclopentadiene at 77 auid catalytic H/D exchauige between benzene, THF, auid a variety of alkauies occurs upon photochemical activation of (n -C,H5)Re(PPh3)H.  

A study of electron transfer catalysed phosphine substitution reactions of Os,(CO),2 and Pe(CO)s initiated by photochemically generated 19-electron species has been 

Ab initio Cl calculations of ground and excited state potential energy surfaces of HCoCCO) have been reported and the two electronic states A auid E found to be close in energy. The molecule reaches by intersystem crossing, and subsequent 

The X-ray structure of the chiral triphenyliriiosphine adduct of [(ii -p-cymene)Ru(L)Q], (L = S-a-mediylbenzylsalicylaldimine), AgC104, has been reported. The X-ray crystal structure of [Ru T -C(CH2)3KTi -C6Hg)] has also appeared.  

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The metal complexes most commonly used in these photoredox systems are manganese and rhenium carbonyls. The proposed mechanism of the photoredox... 

Complexity in the manganese and rhenium pentarbonyl halides substitution arises from the fact that these decompose in inert solvents to form the halogen-bridged dimers [M(CO)4X]2. Both monomers and dimers react with phosphines, arsines, pyridine, aniline etc. to give the disubstituted compounds M(CO)3XL2. Thus three final products or any mixture of them may be obtained, depending upon the precise reaction conditions... 

The discovery of the elements 43 and 75 was reported by Noddack et al. in 1925, just seventy years ago. Although the presence of the element 75, rhenium, was confirmed later, the element 43, masurium, as they named it, could not be extracted from naturally occurring minerals. However, in the cyclotron-irradiated molybdenum deflector, Perrier and Segre found radioactivity ascribed to the element 43. This discovery in 1937 was established firmly on the basis of its chemical properties which were expected from the position between manganese and rhenium in the periodic table. However, ten years later in 1937, the new element was named technetium as the first artificially made element. 

This facile approach to the carbene chemistry of rhenium has not yet been investigated with technetium. Further reactions with the technetium cluster 44a have been performed in C6H6/HC1 to yield the compound [( 6H6)Tc(CO)3]+ (66) which previously had only been described for manganese and rhenium [81]. "Tc-NMR of the latter compound exhibits a resonance at -1983 ppm (relative to [Tc04]- ), and it therefore fits very well into the range proposed for Tc(I) complexes. 

Reaction of the manganese and rhenium carbonyls, M2(CO)10, with Ru3(CO)12 or Os3(CO)12 in a 3 1 ratio yields the products [M(CO)5]2M (CO)4, with M = Re or Mn, M = Ru or Os. These are considered to be linear trinuclear metal systems. The only other trinuclear carbonyl derivative isolated is OsCo2(CO)n, obtained as one of a number of compounds from the reaction of Co2(CO)8 with H2Os(CO)4. No structural data are available for this compound (241). 

The infrared, NMR, and electronic absorption spectra of the two complexes H2FeRu2Os(CO)i3 and H2FeRuOs2(CO)13 have been taken to indicate a structure for these compounds similar to H2FeRu3(CO)13. However, the infrared and low-temperature proton NMR spectra of both compounds indicate that they exist as a mixture of isomers the two projected isomers for H2FeRu2Os(CO)13 are shown in Fig. 58 (247). The mixed manganese and rhenium-osmium complexes, H3MOs3(CO)13, have been prepared by acidification of the reaction mix-... 

Table 13. Enthalpy of formation, AHf (g) and disruption, AH (kj mol x) of alkyl and acyl derivatives of manganese and rhenium carbonyls...

The lower frequency, axial CO stretching mode, peak is well separated in the manganese and rhenium compounds. As suggested by Fig. 8 this is a situation in which intermediate mode behaviour may be expected. Figure 10 shows that this is... 

Indirect Reduction with Mediators Containing Manganese and Rhenium... 

Scheme 28. Manganese and rhenium tricarbonyl complexes with sohd phase linkers (68).

To examine the chemical behavior of these new ligands 48-50 in coordination chemistry, tricarbonyl complexes with manganese and rhenium were synthesized from [MnBr(CO)s] and [ReBrCCOls] as described earlier for the other heteroscorpionate ligands (Scheme 28). The purpose of these tricarbonyl complexes was to verify tripodal binding of the solid-bound ligand. The protected OH linker in 50 acts as model for the solid phase bound ligand. 

Silicon and germanium hydrides react with cobalt, manganese and rhenium carbonyls affording complexes having a silicon (or germanium)-metal bond. These reactions, described previously for inactive compounds have been used in the synthesis of optically active silyl and germyl-transition metals ... 

Like rhenium and ruthenium it crystallizes in a closest packed hexagonal lattice with the metal atoms having the coordination number 12. In Table 2 some properties of technetium are compared with those of manganese and rhenium. 

Existence of technetium was predicted from the vacant position in the Periodic Table between manganese and rhenium. Noddack, Tacke, and Berg reported its discovery in 1925 and named it masurium. The metal actually was never isolated from any source by these workers. Its existence, therefore, could not be confirmed. Perrier and Segre in 1937 produced this element by bombarding molybdenum metal with deuterons in a cyclotron. They named the element technetium derived from the Greek word technetos, meaning artificial. 

The complexes [M(CO)5(> 2-C2H4)] [A1C14] (M = Mn, Re) were first prepared by abstraction of the chloride ligand in M(CO)sCl using aluminum-trichloride under ethylene pressure.14 The preparation of [BF4] salts of these cationic pentacarbonylethene complexes of manganese and rhenium proceeds under very mild conditions (1 bar) and gives high yields.6... 

F,MnO SC6, Manganese( I), pentacarbonyl-(trifluoromethanesulfonato)-, 26 114 F,0 CH, Acetic acid, trifluoro-tungsten complex, 26 222 F,02C,H, Acetic acid, trifluoro-ruthenium complex, 26 254 FjOjSCH, Methanesulfonic acid, trifluoro-iridium, manganese and rhenium complexes, 26 114, 115, 120 platinum complex, 26 126 F304PtSC,4H,5, Platinum(II), hydrido-(methanol)bis(triethylphosphine)-Irans-, trifluoromethanesulfonate,... 

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