THE SYNTHESIS AND CHARACTERIZATION OF ORGANOIMIDO-RE(V) COMPLEXES - THE X-RAY CRYSTAL-STRUCTURES OF [RECL(NC(6)H(4)ME-4) (OME)((T)BUNC)(2)(PPH(3))][BPH(4)] AND [RECL2(NC(6)H(4)ME-4)(PPH(3)) (4-CLC6H4(O)CNNCHPH-O,N)]
Mt. Ahmet et al., THE SYNTHESIS AND CHARACTERIZATION OF ORGANOIMIDO-RE(V) COMPLEXES - THE X-RAY CRYSTAL-STRUCTURES OF [RECL(NC(6)H(4)ME-4) (OME)((T)BUNC)(2)(PPH(3))][BPH(4)] AND [RECL2(NC(6)H(4)ME-4)(PPH(3)) (4-CLC6H4(O)CNNCHPH-O,N)], Polyhedron, 15(12), 1996, pp. 2041-2050
Reaction of [ReCl3(NAr)(PPh(3))(2)] (NAr = NC(6)H(4)Me-4, NC(6)H(3)Me(
2)-2,6) with excess tertiary-butyl isocyanide, ((t)BuNC), in methanol
yielded the red-brown Re(V) arylimido- complexes, [ReCl(NAr)(OMe)((t)B
uNC)(2)(PPh(3))][BPh(4)] where NAr = NC(6)H(4)Me-4, (1) or NAr = NC(6)
H(3)Me-2,6, (2). The X-ray crystal structure of (1) revealed a distort
ed octahedral configuration about the central rhenium atom. The isocya
nide ligands are disposed in a cis configuration and the chloride and
phosphine ligands trans. The remaining sites are occupied by the tolyl
imido- and methoxide ligands. The Re-N(I) bond length of 1.739(3) Angs
trom and Re-N(1)-C(11) angle of 164.8(3)degrees are consistent with th
e imido- ligand functioning as a linear four-electron donor (assuming
the imido-ligand to be neutral). The reaction between the tolylimido-
Re(V) complex, [ReCl3(NC(6)H(4)Me-4)(PPh(3))(2)], and aroylhydrazones,
Ar(O)CNHNCRR'(Ar = Ph, R = R(1) = Me; Ar = 4-ClC6H4, R = H, R(1) = Ph
), in a 1 : 1 toluene/ethanol mixture under reflux yielded the green R
e(V) complexes [ReCl2(NC(6)H(4)Me-4)(PPh(3)){Ar(O)CNNCRR'-ON}] were Ar
= Ph, R = R' = Me (3) or Ar = 4-ClC6H4, R = H, R' = Ph (4). Complex (
3) can also be synthesized from the reaction of [ReCl3(NC(6)H(4)Me-4)
(PPh(3))(2)] and the hydrazone generated in situ from benzoic hydrazid
e in a 1:1 toluene/acetone mixture. The X-ray crystal structure of (4)
showed a distorted octahedral geometry with the oxygen and nitrogen a
toms of the chelated hydrazone (1-) ligand being mutually cis. The nit
rogen atom of the tolylimido- ligand is trans to the chelated oxygen a
nd the phosphorus atom of the triphenylphosphine ligand is trans to th
e chelated nitrogen. The remaining sites are filled by the two chlorid
e ligands. The Re-N(3) bond length of 1.706(5) Angstrom and Re-N(3)-C(
11) angle of 175.7(5)degrees are consistent with the imido- ligand fun
ctioning as a linear four-electron donor.