| Autor: |
Harrison DJ; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, Ontario, L5L 1C6, Canada., Lough AJ; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada., Fekl U; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, Ontario, L5L 1C6, Canada. |
| Abstrakt: |
The complex cation in the title compound, (carbonyl-1κ C )(1η 5 -penta-methyl-cyclo-penta-dien-yl)(μ-2,3,9,10-tetra-methyl-1,4,8,11-tetra-thia-undeca-2,9-diene-1,11-diido-1κ 2 S , S ''':2κ 4 S , S ', S '', S ''')ironnickel( Fe - Ni ) hexa-fluoro-phosphate, [FeNi(C 10 H 15 )(C 11 H 18 S 4 )(CO)]PF 6 or [Ni( L ')FeCp*(CO)]PF 6 , is composed of the nickel complex fragment [Ni( L ')] coordinated as a metalloligand (using S 1 and S 4 ) to the [FeCp*(CO)] + fragment, where ( L ') 2- is [S-C(Me)=C(Me)-S-(CH 2 ) 3 -S-C(Me)=C(Me)-S] 2- and where Cp* - is cyclo -C 5 (Me) 5 - (penta-methyl-cyclo-penta-dien-yl). The ratio of hexa-fluoro-phosphate anion per complex cation is 1:1. The structure at 150 K has ortho-rhom-bic ( Pbcn ) symmetry. The atoms of the complex cation are located on general positions (multiplicity = 8), whereas there are two independent hexa-fluoro-phosphate anions, each located on a twofold axis (Wyckoff position 4 c ; multiplicity = 4). The structure of the new dimetallic cation [Ni( L ')FeCp*(CO)] + can be described as containing a three-legged piano-stool environment for iron [Cp*Fe(CO)'S 2 '] and an approximately square-planar 'S 4 ' environment for Ni. The NiS 2 Fe diamond-shaped substructure is notably folded at the S-S hinge: the angle between the NiS 2 plane and the FeS 2 plane normals is 64.85 (6)°. Largely because of this fold, the nickel-iron distance is relatively short, at 2.9195 (8) Å. The structural data for the complex cation, which contains a new unsaturated 'S 4 ' ligand (two C=C double bonds), provide an inter-esting comparison with the known NiFe hydrogenase models containing a saturated 'S 4 '-ligand analogue having the same number of carbon atoms in the ligand backbone, namely with the structures of [Ni( L )FeCp(CO)] + (as the PF 6 - salt, CH 2 Cl 2 solvate) and [Ni( L )FeCp*(CO)] + (as the PF 6 - salt), where ( L ) 2- is [S-CH 2 -CH 2 -S-(CH 2 ) 3 -S-CH 2 -CH 2 -S] 2- and Cp - is cyclo-penta-dienyl. The saturated analogues [Ni( L )FeCp(CO)] + and [Ni( L )FeCp*(CO)] + have similar Ni-Fe distances: 3.1727 (6), 3.1529 (7) Å (two independent mol-ecules in the unit cell) and 3.111 (5) Å, respectively, for the two complexes, whereas [Ni( L ')FeCp*(CO)] + described here stands out with a much shorter Ni-Fe distance [2.9196 (8) Å]. Also, [Ni( L )FeCp(CO)] + and [Ni( L )FeCp*(CO)] + show inter-planar fold angles that are similar between the two: 39.56 (5), 41.99 (5) (independent mol-ecules in the unit cell) and 47.22 (9) °, respectively, whereas [Ni( L ')FeCp*(CO)] + possesses a much more pronounced fold [64.85 (6)°]. Given that larger fold angles and shorter Ni-Fe distances are considered to be structurally closer to the enzyme, unsaturation in an 'S 4 '-ligand of the type (S-C 2 -S-C 3 -S-C 2 -S) 2- seems to increase structural resemblance to the enzyme for structural models of the type [Ni('S 4 ')FeCp R (CO)] + (Cp R = Cp or Cp*). |
