Reactions of [RhCl(diene)](2) with bi- and terdentate nitrogen ligands. X-ray structures of five-coordinate complexes

Reaction of [RhCl(diene)](2) (diene = 1,5-cyclooctadiene (COD) or bicyclo[2.2.1] hepta-2,5-diene (NBD)) with the N-N-N nitrogen ligands 2,6-(C(R(1))=N-R(2))(2)C5H3N in CD(2)CL(2) or CH2Cl2 yielded the five-coordinate complexes [RhCl(2,6-(C(H)=N-R(2))(2)C5H3N)(diene)] (diene = NBD; R(2) = i-Pr, t-Bu, and p-anisyl), which has been isolated for NBD but not for COD. A single-crystal X-ray determination showed that [RhCl(2,6-(C(H)=N-p-anisyl)(2)C5H3N)(NBD)] has a distorted trigonal bipyramidal configuration with the pyridyl N-atom, one imine N-atom, and one alkene double bond in the equatorial plane, while the second alkene bond and the chloride atom occupy the axial positions. This conformation containing one noncoordinated imine moiety is clearly retained at 183 K in CD2Cl2, as is also the case for the other complexes. For the COD complexes, the reaction is more complicated, as the intermediates that are observed depend on the substituents R(1) and R(2) of the N-N-N nitrogen ligand. The five-coordinate complexes [RhCl(2,6-(C(R(1))=N-R(2))(2)C5H3N)(COD)] could be observed at low temperatures for R(1) = H and R(2) = i-Pr, t-Bu, and p-anisyl, while for R(1) = Me and R(2) = p-anisyl, this intermediate could not be observed; instead, [Rh(2,6-(C(Me)=N-p-anisyl)(2)C5H3N)(2)]Cl-+(-) was found, which shows the presence of one N-N-N Ligand bonded as a bidentate ligand and one N-N-N Ligand bonded as a terdentate ligand at low temperatures. Further reaction of [Rh(2,6-(C(Me)=N-p-anisyl)(2)C5H3N)(2)]Cl-+(-) with [RhCl(COD)](2) afforded [RhCl(2,6-(C(Me)=N-p-anisyl)(2)C5H3N)] and subsequently, via oxidative addition of CD2Cl2, the complex [RhCl2(CD2Cl)(2,6-(C(Me)=N-p-anisyl)(2)C5H3N)]. The dynamic properties of the five-coordinate diene complexes [RhCl(2-(C(H)=N-R(2))-6-(Me)C5H3N)(NBD)] (R(2) = i-Pr, t-Bu, and p-anisyl), which contain N-N nitrogen Ligands, and of the new complexes [Rh(2-(C(H)=N-R(2))-6-(Me)C5H3N)(NBD)]OTf (R(2) i-Pr, t-Bu, and p-anisyl) and of [Rh(2,2'-bipyrimidine)(NBD)]OTf have been investigated. A single-crystal X-ray determination of [RhCl(2-(C(H)=N-i-Pr)-6-(Me)C5H3N)(NBD)] showed structural features which are analogous to those of RhCl(2,6-(C(H)=N-p-anisyl)(2)C5H3N)(NBD)].