Delocalized electronic interactions in chiral cyclopentadienylrhenium halide complexes. Valence photoelectron spectra of CpRe(NO)(L)X [Cp = .eta.5-C5H5, .eta.5-C5(CH3)5; L = CO, P(C6H5)3; X = Cl, Br, I]

Mechanism of isomerization of rhenium alkylidene complexes [(.eta.5-C5H5)Re(NO)(PPh3)(:CRCHR'R'')]+X- to alkene complexes [(.eta.5-C5H5)Re(NO)(PPh3)(RHC:CR'R'')]+X-: an organometallic Wagner-Meerwein-type rearrangement

“…Thus, the iron fragment [(r;5-C8H8)-Fe(CO)(PPh3)]+ must be a poorer ir donor than the rhenium fragment [(?j5-C5Hs)Re(NO)(PPh3)]+ (I). This conclusion is supported by a variety of other data.13, 33 Cyclopentylidene complex lf+BF4* isomerizes more slowly than propylidene and pentylidene complexes lc, d+PF6". All three of these compounds bear one C« alkyl substituent.…”

Synthesis of Bis(methoxycarbene) and Bis(alkylidene) Ligands Bridging Two Iron Centers in the Cp*Fe(L1)(L2) Series. X-ray Crystal Structure of the Iron Alkylidene [Cp*Fe(dppe)(C(H)Me)][PF6]

“…As a general rule, the coordination of bulky and very electron-releasing ligand around the metal center strongly stabilizes the carbene ligand and inhibits its electrophilic properties at the α carbon atom. Thus, if the iron fragment [CpFe(CO)(PPh 3 )] + is considered as a poorer π donor than the rhenium fragment [CpRe(NO)(PPh 3 )] + as shown by a variety of other data, , an opposite situation is observed between the same rhenium fragment and the iron moiety [CpFe(dppe)] + as clearly shown from the comparison of the redox potentials of isostructural compounds in both series. , …”

“…The bimetallic complexes without a metal−metal bond of general formula I , in which a hydrocarbon chain spans two organometallic building blocks have been the subject of considerable interest. − In contrast, analogous complexes II which contain an organic bridging ligand with terminal carbene function coordinated to organometallic moieties have only been the subject of few reports. − …”

Re2Rh2 μ3-[η1-C(Re):η1-O(Rh):η1-O‘(Rh‘)] Bis(carbon dioxide) Complexes [(η5-C5R5)(L)(NO)Re(CO2)Rh(η4-diene)]2 That Are Structurally Related to Rhodium(I) Carboxylate Dimers [Rh(O2CR)(η4-diene)]2

“…Some preliminary results with the prototypical 1 underscore the high reactivity of these Re 2 Rh 2 bis(μ 3 -CO 2 ) adducts (Figure ). Treatment of 1 with Ph 3 SnCl quantitatively produced Cp*(CO)(NO)ReCO 2 SnPh 3 18a plus [ClRh(COD)] 2 ; dissolution of 1 in CHCl 3 gave [(COD)RhCl] 2 (96% by NMR) and Cp*(CO)(NO)ReCl (98%). Methanolysis of 1 , however, yielded Cp*(CO)(NO)ReCO 2 CH 3 8 (71%) plus [CH 3 ORh(COD)] 2 6b (64%).…”