Carbonyl−Metal Clusters with Mixed O,N-Donor Ligands:  Reactivity of the Ureato Cluster [Ru₃(μ-H)(μ₃-HNCONMe₂)(CO)₉] with Phosphines. Structural Characterization of a Triphenylphosphine Derivative and of a Bis(diphenylphosphido) Derivative Which Also Contains a Bridging η¹-Phenyl Ligand

Abstract

The ureato-bridged carbonyl cluster [Ru 3 (µ-H)(µ 3 -HNCONMe 2 )(CO) 9 ] (1) (H 2 NCONMe 2 ) N,N-dimethylurea) reacts with 1 equiv of triphenylphosphine or diphenylphosphine to give the isostructural derivatives [Ru 3 (µ-H)(µ 3 -HNCONMe 2 )(L)(CO) 8 ] (L ) PPh 3 , PPh 2 H). The X-ray structure of [Ru 3 (µ-H)(µ 3 -HNCONMe 2 )(PPh 3 )(CO) 8 ] indicates that the substitution has taken place on an equatorial position cis to the bridging NH fragment. Treatment of 1 with bis(diphenylphosphino)methane (dppm) affords a mixture of the symmetric (C s ) and asymmetric (C 1 ) isomers of [Ru 3 (µ-H)(µ 3 -HNCONMe 2 )(µ-dppm)(CO) 7 ]. All these reactions take place at room temperature. The phenyl-bridged bis(diphenylphosphido) derivative [Ru 3 -(µ-η 1 -Ph)(µ 3 -HNCONMe 2 )(µ-PPh 2 ) 2 (CO) 6 ] has been prepared by reaction of 1 with 2 equiv of PPh 3 in the presence of alumina and has been characterized by X-ray diffraction methods. The thermolysis of [Ru 3 (µ-H)(µ 3 -HNCONMe 2 )(PPh 2 H)(CO) 8 ] in refluxing THF leads to the phosphido-bridged derivatives [Ru 3 (µ 3 -HNCONMe 2 )(µ-PPh 2 )(µ-CO) 2 (CO) 6 ] and [Ru 3 (µ-H)(µ 3 -HNCONMe 2 )(µ-PPh 2 ) 2 (CO) 6 ]. It has been observed that carbonyl substitution reactions on compound 1 are easier than those previously reported on clusters containing N-and/or P-donor bridging ligands. This seems to be related to the hard-soft character of the bridging ligand: the harder the ligand the more reactive is the cluster in carbonyl substitution reactions.

Reactivity of the Unsaturated Complex [(C6Me6)2Ru2(μ2-H)3]+toward Phosphines: Synthesis and Molecular Structure of the Dinuclear Cations [(C6Me6)2Ru2(μ2-PR2)(μ2-H)2]+and Characterization of the P−C Bond Activation Intermediate [(C6Me6)2Ru2(μ2-PPh2)(μ2-H)(μ<

“…All these compounds are brown, except 2 , which is violet. 1 H NMR spectra of 1 − 4 show a strong coupling constant (30 Hz) between hydrido ligands and the phosphorus atom, in accordance with the value found for [Cp 2 Fe 2 (CO) 2 (μ 2 -PPh 2 )(μ 2 -H)] 5e…”

“…The Ru−C ipso distances are shorter than in the trinuclear complexes [(CO) 6 Ru 3 (μ 2 -PPh 2 ) 2 (μ 2 -Ph)(μ 3 -L)] (L = 2-amino-6-methylpyridinate, 2-mercaptobenzimidazolate, N , N -dimethylurea) containing a bridging η 1 -μ 2 -phenyl group, described by Cabeza et al . (2.29(2)−2.35(2) Å), but these complexes are different inasmuch as the Ru 3 skeleton contains only single Ru−Ru bonds.…”

“…However, the cleavage of carbon−phosphorus bonds has been observed in the case of alkyl-substituted diphosphines such as bis(dimethylphosphino)methane and bis(diphenylphosphino)methane . In ruthenium chemistry, C−P bond cleavage has been almost exclusively observed with arylphosphines in the case of carbonyl clusters, leading to aryl-bridged ruthenium clusters …”

Reactivity of a (μ-Oxo)(μ-hydroxo)diiron(III) Diamond Core with Water, Urea, Substituted Ureas, and Acetamide

“…Deprotonated ureas are uncommon ligands. N-Substituted ureates, like OC(NR 2 )(NR) - and OC(NR) 2- , were occasionally generated as anionic ligands in organometallic chemistry under strictly anhydrous conditions. − There is a limited number of structurally characterized nonorganometallic metal complexes with urea anions. ,− In all of them, deprotonated urea ligands are coordinated through nitrogen (the most basic donor atom), usually as a bridging ligand with μ 2 -N,O coordination mode. Neutral ureas, which are much more common ligands, coordinate almost exclusively via the oxygen atom alone ,, and only rarely form bridges. − This distinction in the coordination mode also applies to complexes 2 − 4 : the neutral OC(NH 2 ) 2 ligand is monodentately O-coordinated in 2 , while deprotonated ureates form μ 2 -N,O bridges in complexes 3 and 4 .…”

The Important Role of Some Ancillary Ligands in the Chemistry of Carbonylmetal Cluster Complexes − Selected Reactivity of Triruthenium Clusters Containing Deprotonated 2-Aminopyridines

“…[Ru 3 (µ‐Ph)(µ 3 ‐apyMe)(µ‐PPh 2 ) 2 (CO) 6 ] (Scheme ) 39. A few more triruthenium clusters containing bridging phenyl groups derived from PPh 3 ligands have been reported in the last few years 17,40−42. It appears that cluster complexes of this type have an unusual ability of stabilizing bridging phenyl groups.…”