From Allenes to Edge-Bridging Allyl Ligands or Face-Capping Alkenyl Ligands on a Triruthenium Hydrido Carbonyl Cluster: An Experimental and DFT Computational Study

Abstract

R 2 =H), react with the hydrazido-capped hydrido carbonyl triruthenium complex [Ru 3 ( μ-H)( μ 3 -κ 2 -HNNMe 2 )(CO) 9 ] (1) in THF at reflux temperature to give the allyl-bridged derivatives [Ru 3 ( μ-κ 3 -H 2 CCHCR 1 R 2 )( μ 3 -κ 2 -HNNMe 2 )( μ-CO) 2 (CO) 6 ], as mixtures of syn-allyl and anti-allyl isomers when R 1 6 ¼ R 2 . These reactions also produce a small amount of an alkenyl-capped derivative, [Ru 3 ( μ 3 -κ 2 -HNNMe 2 )( μ 3 -κ 2 -MeCCHR 1 )( μ-CO) 2 (CO) 6 ], when monosubstituted allenes (R 2 =H) are used. Density functional theory calculations have shown that the reactions that give edge-bridging allyl or face-capping alkenyl derivatives from compound 1 and allene are multistep processes. In both cases, the first step, a bimolecular allene for CO substitution, is rate-limiting. The way the allene approaches the cluster complex determines the formation of an allyl or alkenyl product, since this fact decides the final destiny of the hydride ligand, which can be transferred to the central C atom of the allene to give an allyl product or to the terminal CH 2 fragment of the allene to give an alkenyl product. † Part of the Dietmar Seyferth Festschrift. Dedicated to Professor Dietmar Seyferth, to whom all organometallic chemists are indebted.

Coupling of acetylene molecules on ruthenium clusters, involving cleavage of C–Si bonds in the alkyne and coordination of a phenyl ring of a SiPh3 group

“…Bond parameters are very similar to those reported previously and compound 2 also has two semi-bridging carbonyl groups. A comparison of allene C-C bond lengths of compound 2 with those of a Ru 3 -allyl derivative recently described 17 shows much shorter values for 2 (1.329(13) Å vs. 1.426(6) Å in the allyl complex) but it is difficult to evaluate the effect of the hydrazide ligand also present in the second case. The solid state structures for the three related compounds were obtained and are shown in Fig.…”

Carbon–Carbon Bond Coupling of Vinyl Molecules with an Allenyl Ligand at a Diruthenium Complex

“…5.6 and 5.4 ppm, in accordance with the trans geometry, which has also been recognized in the solid-state structures; since 3 prevalently exists as a cis isomer, the formation of 4–9 takes place with cis to trans rearrangement. The allylic C 5 –H and C 4 –H hydrogens resonate within the ranges 5.70–4.44 and 4.24–3.34 ppm, respectively, and the C 1 H 2 group gives rise to two distinct signals at significantly different chemical shifts (e.g., at 4.08 and 2.64 ppm in the case of 4 ). Salient 13 C NMR features are provided by the two terminal carbonyl ligands (197–204 ppm) and the five carbons directly involved in metal coordination [e.g., in the case of 4 : δ/ppm = 39.2 (C 1 ), 70.9 (C 2 ), 73.7 (C 3 ), 76.0 (C 4 ), and 67.8 (C 5 )].…”

Touching the upper limit for ferromagnetic interactions in hetero-bridged dinuclear [Cu2II] complexes using a novel N5-dinucleating ligand bearing an endogenous monoatomic amido(R–NH−)-bridging group

“…Only a few examples of ferromagnetically coupled heterobridged dinuclear copper(II) have been reported so far, and in all of them the ferromagnetic interactions are caused by orbital countercomplementarity (the two bridges counterbalance their effects) either between two bridges with AF contributions or with F/AF contributions. 19,23 In view of this, the fact that compounds 1 and 2 exhibit the largest ferromagnetic interactions ever observed for heterobridged dinuclear copper(II) complexes (and comparable to the larger found for homodinuclear (II) complexes, 24 In summary, a novel N 5 -dinucleating ligand has been specifically designed to prepare amido-bridged metal complexes. We have succeeded in obtaining for the first time and in mild conditions, single and…”

“…These types of complexes, particularly those containing copper(II) ions, have received much attention for their interesting and diverse magnetic properties, which are in general due to the cooperation effect of the different bridging ligands (namely orbital complementarity and countercomplementarity). 19 Orbital countercomplementarity, together with magnetic orbital orthogonality, spin-polarization, double-exchange and crossed-interactions are the most important mechanisms for producing ferromagnetic interactions between metal ions. 20 It should be noted that although a huge number of polynuclear paramagnetic complexes exhibiting magnetic exchange interactions between metal centres have been reported so far, in only a few are the interactions ferromagnetic in nature.…”