
%0 Journal Article
%A Horn, E 
%A Snow, MR 
%T Aqua and perfluoro anion (BF<sub>4</sub><sup>-</sup>, AsF<sub>6</sub><sup>-</sup>) coordination isomers of manganese and rhenium carbonyls
%J Australian Journal of Chemistry
%D 1984/07/01
%V 37
%N 7
%P 1375-1393
%K 
%R https://doi.org/10.1071/CH9841375
%U https://www.publish.csiro.au/paper/CH9841375 
%X Pentacarbonyl- and tricarbonyl-rhenium bromide complexes react with AgAsF6 and AgBF4 in dichloromethane to form the respective aqua species, [Re(CO)5(OH2)]+ Y- (where, Y = AsF6-, BF4-) and [Re(CO)(L2)(OH2)]+ BF4- [where L2 = bpy, dppe, P(OPh)3].* A variable-temperature 19F nuclear magnetic resonance study of the [Re(CO),3(tmen)(OH2)]+ BF4- system establishes that an equilibrium exists between the coordinated and 'free' tetrafluoroborate anion in solution (CD2Cl2): Re(CO)3(tmen)FBF3 + H2O &#8496; [Re(CO)3(tmen)(OH2)]+ + BF4- This equilibrium is forced to the right by low temperature (c. -10&#176;C) and by removing the water with phosphorus pentoxide. Thus, under controlled reaction conditions (c. - 10&#176;C, dry nitrogen atmosphere), AsF6- and BF4- are seen by infrared spectra to be coordinated in the complexes Re(CO)3(bpy)FAsF5.&#948;(H2O) and Re(CO)3(tmen)FBF3.&#948;(H2O). The species [Re(CO)3(L2)(OH2)]+ Y- [where (i), L2 = 2CO, Y = AsF6-; (ii), L2 = tmen, Y = AsF6-, BF4-] have been characterized by their crystal structures. Crystals of [Re(CO)5(OH5)]+ AsF6- are monoclinic, space group C2/c with a 27.085(5), b 7.208(1), c 13.404(3) &#506; and &#946; 105.50(1)&#176;. A full-matrix least-squares refinement when using the absorption corrected data converged with R = 0.027 and R, = 0.028. The species [Re(CO)3(tmen)(OH2)] + AsF6- crystallizes in the monoclinic space group P2, with a 7.858(1), b 15,68(1), c 7.887(2) &#506; and &#946; 117.11(1)&#176;. The final full-matrix refinement converged with R = 0.021 and Rw = 0.022. [Re(CO)3(trnen)(OH2)]+ BF4- crystallizes in themonoclinic space group C2/m with a 14.134(4), b 16.010(4), c 7.729(1) &#506; and &#946; 113.16(2)&#176;. In these structures the water molecule coordinates to the rhenium(1) at an average distance of 2,246(5) &#506;. This is significantly larger than the rhenium-fluoride bond length of 2.040(4) &#506;. Similar manganese aqua complexes, [Mn(CO)3 {P(OPh)3}2(H2O)]+ Y- (where, Y- = AsF6-, BF4-), also exhibit the same infrared features characteristic of coordinated water [i.e. the presence of sharp &#948;(H-O-H) bending absorption near 1600 cm-1]. This feature is absent from all the species which only have lattice water and a coordinated fluoro anion. 
