No abstract

FeRu(CO)6(t-Pr-DAB) (1) [R-DAB = RN=CHCH=NR] reacts at 20 °C with dimethyl acetylenedicarboxylate in heptane solution to give the complexes FeRu(C0)5(i-Pr-DAB)[Ai2,i72-Me0C(0)(>=CC(0)0Me] (2) , with DAB chelating the Ru center and the alkyne in perpendicular bridging position, and FeRu-(CO)5[i-PrN-CHCH(N-i-Pr)C(C(0)0Me)=CC(0)0Me] (4) in which the alkyne is C-C coupled with the t?2-C=N coordinated imine C atom of the DAB ligand (in 1). In 4 both N atoms are bonded to Fe whereas in 1 they are bonded to Ru which suggests that the formation of 4 is preceded by an isomerization of 1 involving the migration of the ij2-C=N coordinated imine fragment from Fe to Ru. The X-ray crystal structure of 4 has been determined. Dark brown crystals of 4 (FeRuC19Ho2N209, mol wt 579.31, Z = 4) are monoclinic, space group P2x/a, and have cell constants o = 14.858 (1) k,b = 17.055 (1) A, c = 9.4289 (8) A, and ß = 94.215 (8)°. A total of 3092 reflections (Mo , µ = 12.77 cm-1) were used in the refinement which converged to a final R of 0.053 (Rv = 0.096). Complex 2 shows a thermally induced (70 °C) isomerization which involves the migration of one of the isopropyl methine protons to the alkyne which is transformed into an V-vinyl fragment in FeRu(C0)5[Me0C(0)C=CHC(0)0Me][Me2C=NCHCHN-t-Pr] (3) . Reaction of 1 at 20 °C with methyl propynoate produces a mixture of two pairs of isomeric complexes, FeRu(C0)5(i-Pr-DAB)^2-HC=CC(0)0Me) (8, 9) and FeRu(C0)4(t-Pr-DAB)^2-HC=CC(0)0Me) (10, 11). The isomeric complexes differ with respect to the coordination of the alkyne relative to the Fe-Ru core. In all complexes 8-11 the DAB ligand is bonded as a , -, ', /2,7)2-0= ,0= ' bridging 8e donor with the N atoms -bonded to Ru and the alkyne as a p2-parallel bridging ligand. In 8 and 9 a fifth CO ligand is bonded to Ru and the metal centers are at a long nonbonding distance of 3.089 (2) A. The reaction of 10 and 11 with CO at 20 °C yields 8 and 9, respectively, in quantitative yield. Both 8 and 9 again easily lose a CO ligand when a solution of these compounds is purged with N2. The X-ray crystal structure of 8 has been determined. Yellow crystals of 8 (FeRuC17H20N2O7, mol wt 521.27, Z = 8) are orthorhombic, space group Pnab, and have cell constants a = 15.263 (2) A, b = 18.458 (2) A, and c = 15.130 (2) A. A total of 4027 reflections (Mo , µ = 14.57 cm™1) were used in the refinement which converged to a final R of 0.050 (Rv = 0.081). In the reaction of 1 in n-octane at 90 °C with ethyne four products are formed, of which three are the isomeric metallacyclopentadienyl complexes FeRu[HC=CHCH=€H] (CO)4(i-Pr-DAB) (12)(13)(14). In 14 (yield 20%) the DAB ligand is chelating Fe which is bonded to the RuC4 metallacycle. In 12 and 13 (both obtained in 15-20% yield) the DAB ligand is bonded to Ru and Fe, respectively, which metal atom is also part of the metallacycle. The fourth complex (15) (yield 5%) has the composition FeRu(CO)6(t-Pr-DAB)(C2H2) and probably has a flyover structure in which a CO molecule is C-C coupled to the alkyne which is N-C coupled to DÁB...

No abstract

Ru2(CO)5('Pr-DAB) (1) reacts with Mel at room temperature to give Ru2(Me)(I)(CO)4('Pr-DAB) (2a), and a single-crystal X-ray structure determination of 2a has been obtained. Crystals of 2a are orthorhombic, space group Pbca, with unit-cell dimensions a = 16.2510 (10) A, b = 13.2660 (10) A, and c = 17.2410 (10) A. The molecular structure consists of a Ru(Me)(CO)2 fragment and a Ru(CO)2 fragment, held together by an iodide bridge and a bridging a-diimine ligand. The DAB ligand is coordinated to the Ru(Me)(CO)2 fragment via both nitrogen atoms and to the Ru(CO)2 fragment via an r/2 coordination of both imine bonds. Treatment of 2a with CO leads to substitution of the iodide bridge and the two coordinated imine bonds with the formation of Ru(Me)(I)(CO)2('Pr-DAB) (3a) and Ru(CO)6. This reaction, which is reversible, provides a new synthetic route for the preparation of monomeric methylated a-diimine complexes. Several other reaction routes for the formation of the complexes Ru(X)(Y)(CO)2(a-diimine

No abstract