ν5-Cyclopentadienylrhodium(I) Complexes containing Diphosphines and their Reactions with the Electrophiles H(1+) and Me(1+). Crystal and Molecular Structure of , a Complex with a Unidentate Bis(diphenylphosphino)methane Ligand

Article abstract of DOI:10.1039/DT9830000433

The compounds (2), (3), and (4) were obtained from the reactions of (1) with bis(diphenylphosphino)-methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), and 1,3-bis(diphenylphosphino)propane (dppp) respectively.The X-ray structure determination of (2) shows it to crystalize in the space group P2₁/n with unit cell dimensions a = 13.734(4), b = 9.771(3), c= 20.440(8) Angstroem, β = 103.9(1) deg, and Z = 4.R' = 0.05 for 2 864 observed reflections.Some relevant bond distances areRh-(centroid of C5H5 ring) = 1.932, Rh-P = 2.238(2), and Rh-C(carbonyl) = 1.806(8) Angstroem.The bonding of the dppm ligand is, unusually, unidentate to the metal.The Reactions of (2), (3), (4), and of the previously reported complex <2(μ-dppb)> (6) , with the electropilic agents H(1+) and Me(1+) have been studied.Complex (3) reacts with HBF4 to give the cationic hydride BF4 (5); in the same reaction (4) and (6) gave unstable products.The protonic attack of HCl on (3), (4), and (6) results in the formation of compounds devoid of co-ordinated cyclopentadienyl ion.The binuclear complex <2(μ-dppb)> (7) was the product of the reaction of (6) with HCl; for this reason a possible mechanism is proposed.The reactions of HCl with (3) and (4) are more complex and mixtures containing <n> and the rhodium (III) hydride <n> (n = 1 or 2, P-P = dppe or dppp) were isolated.The compound <2> was formed by the reaction of (5) with Cl.The electrophilic attack of MeI on (2) takes place either at the metal or at the unco-ordinated phosphorus atom of dppm and the reaction product is I.MeI reacts with (3) and (4) to give I and I, which are very unstable in solution.

Full text of DOI:10.1039/DT9830000433

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