Synthesis and structural features of complexes [(P P)(2)Rh][hfacac] containing hexafluoroacetyl-acetonate as a noncoordinating anion

The synthesis and characterization of complexes [(P P-boolean AND)(2)Rh][hf acac] ((PP)-P-boolean AND = chelating bidentate phosphine ligand R2P(CH2)(n )PR2 (2a-g), hfacac = hexafluoroacetylacetonate anion) (4) is reported. The molecular structures of 4a (R = Ph, n = 1) and 4f (R = Cy, n = 2) in the s olid state were determined by single-crystal X-ray diffraction. The complex es crystallize in the monoclinic space groups C2/c (No. 15) and P2(1)/n (No . 14), respectively. No coordinative interaction between the rhodium center of the cation [((PP)-P-boolean AND)(2)Rh](+) (4a(+), 4f(+)) and the hfacac anion is evident in either cases. In the crystal structure of 4a, hydrogen bonds between the oxygen atoms of the hfacac anion and methylene protons o f the CH2 bridges of the phosphine ligand lead to highly symmetric chains o f regularly alternating cations and anions. The coordination geometry aroun d the rhodium center in 4a(+) is ideally square-planar, whereas 4f(+) is si gnificantly distorted towards a tetrahedron with an angle between the two P 2Rh moieties of 18.6 degrees. The cation 4b(+) (R = Cy, n = 1) was investig ated in form of the tetrafluoroborate salt for comparison. The compound [{C y2P(CH2)PCy2}(2)Rh][BF4] crystallizes as a THF solvate (4b ) in the triclin ic space group P (1) over bar (No. 2) containing ideally square-planar [((P P)-P-boolean AND)(2)Rh](+) cations.