Dimolybdenum and ditungsten cyclopentadienyl carbonyls with electron-rich phosphido bridges. Synthesis of the hydrido phosphido complexes [M2Cp2(mu-H)(mu-PRR ')(CO)(4)] and unsaturated bis(phosphido) complexes [M2Cp2(mu-PR2)(mu-PR ' R '')(CO)(x)] (x=

摘要

New hydrido complexes of the type [M2Cp2(mu-H)(mu-PRR')(CO)(4)] (M = Mo, W) have been prepared through the thermal reaction Of [Mo2Cp2(CO)(6)] with HPCy2, H2PCy, or HPEt2 or the thermal reaction Of [W2Cp2(CO)(4)] with HPR2 (R = Cy, Et, Ph). In contrast, UV irradiation Of [M2CP2(CO)(6)] and HPRR' leads with good yield to the bis(phosphido) complexes [M2Cp2(mu-PRR')(2) (mu-CO)] (R = R'= Cy, Et, Ph; R = Cy, R'= H). Related complexes having different phosphido groups, [M2Cp2(mu-PR2)(mu-PR'R")(mu-CO)] (R = Cy, Bu-t, Ph; R' = Cy, Bu-t, Et; R" = Cy, Bu-t, Et, H), can be prepared in high yield through the photochemical reaction of [M2Cp2(mu-PR2)(mu-H)(CO)(4)] and HPR'R" or [M2Cp2(mu-H)(mu-PR'R")(CO)(4)] and HPR2. All triply bonded compounds react easily with carbon monoxide at room temperature or under moderate heating to finally yield the corresponding trans-dicarbonyl complexes [M2Cp2(mu-PRR')(2)(CO)(2)] or [M2Cp2(mu-PR2)(mu-PR'R")(CO)(2)]. Some of the intermediates in these carbonylation reactions have been identified, including the cis-dicarbonyl complex [Mo2Cp2(mu-PPh2)(mu-(PBu2)-Bu-t)(CO)(2)] and the tricarbonyl complex [Mo2Cp2(mu-PEt2)(2)(CO)(3)]. The structures of the new complexes are analyzed on the basis of the corresponding IR and NMR (H-1, P-31, C-13) data, and the reaction pathways operative in these highly efficient syntheses of bis(phosphido) complexes is discussed on the basis of the available data and some cross-experiments. [References: 40]