Ruthenium carbonyl 1,4-diaza-1,3-butadiene (R-DAB) complexes. A theoretical and experimental investigation of the electronic structure of Ru2(CO)4(R-DAB)(.mu.-CO) and Ru2(CO)4(R-DAB)(.mu.-HC.tplbond.CH)

Abstract

The electronic structure of two binuclear ruthenium clusters containing the 8e donor 1,4-diaza-l,3-butadiene (R-DAB) ligand [Ru,(CO),(R-DAB)(p-CO) and Ru,(CO),(R-DAB)(pHC=CH)] is for the first time discussed by using SCF first principle discrete variational (DV) X a calculations and gas-phase UV photoelectron (PE) spectroscopy. Despite the short metal-metal interatomic distance, the bonding scheme of both molecules is dominated by the absence of any direct metal-metal bond. On the contrary, the importance of a strong multicentered interaction involving the p-bridged ligands has been emphasized. As far as the R-DAB moiety is concerned, theoretical results indicated a poorer involvement of n+ and nlinear combinations of nitrogen lone pairs than rj* and r2 levels in metals-R-DAB interactions. Looking into the nature of such a r interaction it has been found that the Ru atom of the metallacycle fragment is mostly involved in M -r3* back-bonding while r2 -

Bridging diimino and ene-diamido ligands in binuclear compounds: structural and electronic features

“…Both compounds were analyzed theoretically in an early work [17]. Our results are in agreement with the bonding description presented in that paper except for the proposed lack of the metal-metal bond.…”

“…metal character and determine the poor metal-metal overlap population, pointed out by the authors [17].…”

“…In the last decade, the number of theoretical papers dedicated to the investigation of mononuclear species containing ene-diamido or diimino ligands have increased markedly [7][8][9][10][11][12][13][14][15][16]. Today, the number of theoretical studies devoted to binuclear systems with a bridging diimino ligand is still limited [17], although the chemistry of binuclear species containing bridging diimino ligands was initiated and developed several years ago by Vrieze and coworkers [18,19]. We have recently shown that the oxidation of binuclear ruthenium complexes of this type affects mainly the bridge and transforms the o-phenylenediamido ligand into a o-diiminobenzene one.…”

Coupling of iminoacyl groups to diazabutadienes on manganese carbonyl complexes

“…73 Recent MO calculations suggest that the Ru-Ru bonding character of the LUMO coupled with its antibonding character between the µ-CO and DAB ligands is responsible for its reactivity with CO and other small molecules. 74 The Ru complexes that undergo coupling reactions are those having a vacant coordination site on Ru or having only one 7?2-C=N. 69 The unreactivity of our Mn dimers may be connected to the coordinative saturation at all metal centers.…”

Binuclear Complexes of Ruthenium and Osmium Containing Metal Metal Bonds

“…Also the ruthenium atom o f the metallacycle fragment is mostly involved in metal-II 3 * backbonding while n 2 -metal donation primarily involves the second ruthenium atom. 84 Compound (49) (R 1 = R 2 = Bu l ) reacts with a range o f other alkynes, R 3 C=CR 4 (R 3 = Ph, CO 2 Me, R 4 = H; R 3 = R 4 = CO 2 Me, CF 3 ), to a f f o r d [Ru 2 (CO) 6 {Bu t N=CHCH(NBu t )CR 3 CR 4 }] (68)* in high yield in which the alkyne has been incorporated into the bridging ligand. 85 ' 86 The proposed mechanism for the formation of these species involves the direct electrophilic attack o f the alkyne on the r| 2 -C=N coordinated imine moiety, leading to the observed C-C bond formation.…”