SYNTHESIS, STRUCTURE, AND REDOX CHEMISTRY OF HETEROPOLYMETALLIC CARBON COMPLEXES WITH MC(2)M', MC(4)M', AND MC(4)M'C(4)M LINKAGES - TRANSMETALATIONS OF LITHIOCARBON COMPLEXES (ETA(5)-C(5)ME(5))RE(NO)(PPH(3))(C-CLI) AND (ETA(5)-C(5)ME(5))RE(NO)(PPH(3))(C-CC-CLI)

Reactions of (eta(5)-C(5)Me(5))Re(NO)(PPh(3))(C=CLi) and trans-Pd(PEt(3))(2)(Cl)(2) or trans-Rh(PPh(3))(2)(CO)(Cl) give heterobimetallic C-2 complexes trans-(eta(5)-C(5)Me(5))Re(NO) (PPh(3)) (C=C)Pd(PEt(3))(2)(Cl) (3, 66%) or trans-(eta(5)-C(5)Me(5))-Re(NO)(PPh(3))(C=C)Rh(PPh(3))(2)(CO) (4, 72%). Reaction of [(eta(5)-C(5)Me(5))Re(NO)(PPh(3))(ClC6H5)](+) BF4- and HC=CC=CSiMe(3) gives [(eta(5)-C(5)Me(5))Re(NO)(PPh(3))(HC=CC=CSiMe(3))](+) BF4- (93%; HC=C ligated), which with t-BuOK and K2CO3/MeOH yields (eta(5)-C(5)Me(5))Re(NO)(PPh(3))(C=CC=CH) (9, 84%). Reaction of 9 and n-BuLi gives (eta(5)-C(5)Me(5))Re(NO)(PPh(3))(C=CC=CLi) (10), which is trapped by MeI as (eta(5)-C(5)Me(5))Re(NO)(PPh(3))(C=CC=CMe) (85%). Reaction of 10 and trans-Pd(PEt(3))(2)(Cl)(2) (2:1) gives trans-(eta(5)-C(5)Me(5))Re(NO)(PPh(3))(C=CC=C)Pd-(pEt(3))(2)(C=CC =C)(Ph(3)P)(ON)Re(eta(5)-C(5)Me(5)) (12, 73%). At a 1:1 stoichiometry, trans-(eta(5)-C(5)Me(5))Re(NO)(PPh(3))-(C=CC =C)Pd(PEt(3))(2)(Cl) (13) is the major product. Cyclic voltammograms of 3, 12, and 13 show reversible one-electron oxidations. Reactions of 3 and 12 with (eta(5)-C5H5)(2)Fe-.+ PF6- give the radical cations 3(.+) PF6- and 12(.+) PF6-. These are unstable at room temperature, but ESR data show the odd electrons to be localized on (one) rhenium. Complexes 3 and 4 (but not 12 and 13) exhibit restricted rotation about the ReC(x)M moiety, as evidenced by two R(3)PMPR(3) P-31 NMR signals at low temperature (Delta G double dagger(T-c) = 11.7-10.9 kcal/mol). The crystal structure of 3 shows eclipsed PEt(3) ligands.