Ruthenium carbonyl 1,4-diaza-1,3-butadienes (R-DAB) complexes. 10. Facile preparation of Ru(CO)3(R-DAB) and its relation to the reversible carbon-carbon bond formation and fission between two R-DAB ligands on a diruthenium fragment

1,3-Dipolar cycloaddition to the FeSC fragment 20. Preparation and properties of carbonyliron complexes of di-thiooxamide. Reactivity of the mononuclear (di-thiooxamide)Fe(CO)3 towards dimethyl acetylenedicarboxylate

“…A similar pattern is observed for the (alkyl-DAB)M(CO) 3 (M= Fe, Ru) [31,[76][77][78] complexes. The position of the CO stretching bands of 7a,d compare well with those of Fe(CO) 3 (p-Tol, p-An-DAB) [32], suggesting that the DTO ligands also possess a similar low-lying p*-LUMO level.…”

“…Comparable shifts to lower frequency have been observed for the ketone carbon atom in Fe(CO) 3 (a-iminoketone) [33], whereas somewhat smaller shifts have been found for the imine carbon atoms in Fe(CO) 3 (R-DAB) [32] and Fe(CO) 3 (a-iminoketone). The three terminal CO ligands in complexes 7a,d give rise to a single resonance at 213.6 and 210.8 ppm indicating that they rapidly interchange on the NMR time scale at 263 K. This interchange has also been observed for the M(CO) 3 (R-DAB) (M = Fe, Ru) [76,82,83] and Fe(CO) 3 (a-iminoketone) and may be explained by Berry pseudo-rotations [84].…”

Preparation and Properties of Carbonyliron Complexes of 1-Aza-4-oxa-1,3-butadiene (α-Imino Ketone) – X-ray Crystal Structures of Fe(CO)3[MeNC(Ph)C(Ph)=O] and Fe2(CO)4[tBuNC(H)(Me)C(O)(O)C(Me)C(H)=NtBu]

“…In complex 5, a C-C coupling reaction occurs between the imine C atoms of two α-imino ester ligands. This type of C-C coupling has also been observed in the reaction of R-DAB and R-Pyca with carbonylruthenium compounds, [7] leading to [Ru 2 (CO) 4,5 (R-ADA)] (cf. Table 1) and [Ru 2 (CO) 4,5 (R-APE)] (cf .…”

“…The two intact imine moieties are bonded to the iron centre by normal Fe-NϭC σ-donor bonds [Fe (1) , it was concluded from several structural features that the iPr-ADA ligand is forced to coordinate to the ruthenium centres which might explain the facile thermal rupture of the central C-C bond in this complex. [7] From the observed bond angles and lengths in 8a it appears that the tBu-ADO ligand exhibits no geometrical constraints that could explain the facile fission of the C(6)-C(8) bond under carbon monoxide. The newly formed C-C connective bond C(6)-C(8) in 8a of 1.587(8) Å is, however, significantly longer than a normal C(sp 3 )-C(sp 3 ) bond.…”

“…[1][2][3][4][5] The ability to donate the nitrogen lone pairs and the (CϭN) imine π-bonds results in a flexible coordination behaviour in which the α-diimine ligand can donate from 2 to 8 electrons to one or more metal centres. An interesting aspect of this versatile coordination behaviour is the activation of the imine bond towards C-C, C-H, C-N, and N-H coupling reactions of R-DAB ligands in the coordination sphere of transition metals with a variety of unsaturated molecules, such as α-diimines [6][7][8][9][10] carbodiimides [11] sulfines, [11] and alkynes. [12][13][14][15][16][17][18] In a series of previous papers [19][20][21][22][23][24] we have reported in detail on the C-C coupling reaction of the [(R-DAB)Fe(CO) 3 ] complexes 1 (cf.…”