BINUCLEAR PENTAMETHYLCYCLOPENTADIENYL DIRHODIUM COMPLEXES WITH PYRAZOLATO AND DIPHENYLPHOSPHIDO BRIDGING LIGANDS

The reaction of [{Rh(C(5)Me(5))}(2)(mu-L)(mu-OMe)(2)]BF4 [L = pyrazola te (pt), 3-methylpyrazolate. 3,5-dimethylpyrazolate or 3(5)-bromo-5(3) -methylpyrazolate] with HPPh(2) has been studied. Complexes of general formulae [{Rh(C(5)Me(5))}2(mu-L)(mu-OH)(mu-PPh(2))]BF4, [{Rh(C(5)Me(5 ))}(2)(mu-L)(-PPh(2))2]BF4 and [{Rh(C(5)Me(5))}(2)(mu-OH)(2)(mu-PPh(2) )]BF4 were prepared and characterized by analytical and spectroscopic means. The crystal structure of [{Rh(C(5)Me(5))}(2)(mu-pz)(mu-PPh(2))( 2)]BF4 . CHCl3 was determined. The rhodium atoms show pseudo-octahedra l geometry and are separated by 3.473(1) Angstrom. The mu-hydroxo comp lexes [{Rh(C(5)Me(5))}(2)(mu-L)(mu-OH)(mu-PPh(2))]BF4 react with hydro chloric acid affording the corresponding mu-chloride compounds [{Rh(C( 5)Me(5))}(2)(mu-L)(mu-Cl)(mu-PPh(2))]BF4, which in turn have been also prepared from [{Rh(C(5)Me(5))}(2)(mu-OH)(3)]BF4, HL, HPPh(2) and HCl in 1:1:1:1 ratio. The crystal structure of [{Rh(C(5)Me(5))}2(mu-pz)(mu -Cl)(mu-PPh(2))]BF4 . CHCl3 has been determined. Two (C(5)Me(5))Rh moi eties are connected by three different anionic ligands, pz, Cl and PPh (2). The rhodium atoms are separated by 3.432(1) Angstrom. Aged soluti ons of reaction mixtures of [{Rh(C(5)Me(5))}(2)(mu-L)(mu-OMe)(2)]BF4 a nd HPPh(2) contain h(C(4)Me(5))}(2)(mu-Ph(2)PO(2))(2)(mu-PPh(2))]BF4, the diphenylphosphinato ligands arising from Ph(2)P(O)OH, an oxidation product of HPPh(2). The crystal structure of the solvate has been est ablished. Two Ph(2)PO(2) groups and a PPh(2) ligand bridge two (C(5)Me (5))Rh units. The rhodium-rhodium distance is 4.049(1) Angstrom. The m u-hydrido complex [{Rh(C(5)Me(5))}(2)(mu-H)(mu-pz)(mu-PPh(2))] has bee n prepared by treating [{Rh(C(5)Me(5))}(2)(mu-OH)(3)]BF4 with Hpz and HPPh(2) in refluxing propan-2-ol.