Syntheses, structure characterisation and X-ray studies of some mono, di- and tri-substituted cluster complexes of Ru3(CO)12 substituted by bulky fluorinated phosphine ligands

Five trinuclear substituted complexes of the type Ru₃(CO)₁₁L, Ru₃(CO)₁₀L₂ and Ru₃(CO)₉L₃ were synthesised by the reaction of Ru₃(CO)₁₂ with fluorine substituted phosphine ligands, {P(C₆H₄F-m)₃ and P(C₆H₄F-p)₃}, using the radical anion catalysed method. The structures of the resulting clusters were elucidated by means of elemental analyses and spectroscopic methods, which included IR, ¹H, ¹³C and ³¹P NMR spectroscopy. X-ray crystallographic studies of four of the complexes were carried out. In all the complexes, the ligand occupies an equatorial position due to steric reasons, and coordination of the ligand is observed only at the phosphorus atom. In the two monosubstituted complexes, Ru₃(CO)₁₁P(C₆H₄F-m)₃ and Ru₃(CO)₁₁P(C₆H₄F-p)₃, the effect of substitution resulted in an increase in the Ru-Ru distances. Out of the three Ru-Ru bonds, the one which is cis to the ligand is noticeably longer than the other two. The asymmetric unit of the disubstituted complex Ru₃(CO)₁₀{P(C₆H₄F-p)₃}₂ is composed of two molecules, A and B. As expected, the two phosphorus ligands are equatorially bonded to two different ruthenium atoms. The asymmetric unit of the trisubstituted complex is composed of one molecule of Ru₃(CO)₉{P(C₆H₄F-m)₃}₃ and one disordered solvent molecule. The structure consists of one triangular ruthenium complex in which each of the phosphorus ligands is equatorially bonded to three different ruthenium atoms. In the structure, disorder of the fluorine atoms is observed. Bond parameters, especially bond lengths and bond angles, are correlated to the structure and also are compared with the literature data of similar compounds.     

Building blocks for phospha[n]pericyclynes

Reaction of i-Pr₂NPCl₂ with acetylenic Grignard reagents resulted in the formation of new acetylenic substituted phosphorus building blocks. These building blocks can be protected by forming the corresponding W(CO)₅ complex and the O and S derivatives for added stability as was demonstrated for aminophosphine (11a). From this building block, very sensitive product mixtures containing tetraphospha[4]pericyclynes (16) were obtained. In addition, the amino-substituent of phosphines (11) could be removed upon treatment with HCl to give chlorophosphine (18) from which novel trisethynylphosphines (19) bearing different substituted alkynes were obtained that may serve as building blocks for novel three-dimensional phospha-acetylenic scaffolds such as the (di)ethynyl-expanded phosphacubanes 8 and 25 that, according to DFT calculations, have a higher degree of cyclic electron delocalization and reduced HOMO-LUMO gaps compared to their carbon-analogues.     

The Reaction of Triphenylmethyl-substituted Primary and Secondary Phosphines with Phosgene

The nature of the products from the reaction of TrtPH₂ ( 1 ) with an equimolar amount of phosgene strongly depends on the solvent. The initial intermediate 2 was isolated from toluene, but lost CO in dichloromethane, and HCl in diethyl ether, yielding TrtP(H)Cl ( 3 ), and (TrtPCO)₂ ( 4 b ), respectively. TrtP(H)Cl ( 3 ) was found to be a halophosphine of amazing stability. Treatment of 3 with excess phosgene led to partial substitution of the P-bonded proton for C(:O)Cl with formation of 5 , which did not eliminate CO to give TrtPCl₂. Substitution of chlorine in TrtP(H)Cl ( 3 ) for fluorine or bromine furnished the halophosphines, 6 and 7 . Minute quantities of the diphosphene 8 were formed upon treatment of 3 with NEt₃ or DBU. The course of the reaction between the secondary phosphines Trt(R)PH and phosgene depends on the group R. If R was t-Bu, formation of a mixture of Trt(t-Bu)PCl ( 10 ), and t-BuPCl₂ (resulting from partial cleavage of the P–C-bond) was observed. Although in the case of R = Ph, the intermediate 12 could be isolated, at elevated temperature HCl was eliminated from 12 , giving Trt(Ph)PCl ( 13 ). The diphosphine (TrtPH)₂ ( 14 ) is inert towards HCl-free phosgene. In the presence of HCl the P–P-bond in 14 was cleaved, and upon chlorination of the resulting TrtPH₂ ( 1 ) by phosgene, TrtP(H)Cl ( 3 ) was obtained as the only phosphorus-containing product.     

Supported Organometallic Complexes. XXXVI [1] Diaminediphosphineruthenium(II) Interphase Catalysts for the Hydrogenation of α, β‐Unsaturated Ketones

The T—silyl functionalized diamine‐bis(ether‐phosphine)ruthenium(II) complexes 1a(T ° ) — 1g(T ° ) (Scheme 1) were sol‐gel processed in the presence of different amounts of the co‐condensation agents CH₃Si(OMe)₃ (Me—T ° ) and (MeO)₂SiMe—(CH₂)₆—MeSi(OMe)₂ (D ° —C₆—D ° ) to produce a library of the interphase catalysts X1a — X1c , X2a — X2g , and X3a — X3g . Due to the remarkable electronic and steric effects of the co‐ligands on the catalytic activity of such complexes, a series of aliphatic and aromatic diamines was selected. The new polymers were investigated by multinuclear CP/MAS solid‐state NMR spectroscopy as well as by EXAFS, EDX, SEM, and BET methods. Selected interphase catalysts show high activities and selectivities in the hydrogenation of trans‐4‐phenyl‐3‐butene‐2‐one.     

Organometallic Molybdenum(V) Complexes with Primary Phosphine Ligands. Syntheses,Spectroscopic Properties and Molecular Structures of [Cp°MoCl4(PH2R)] (R = But, 1‐Ad,Cy, Ph, 2, 4, 6‐Me3C6H2, 2, 4, 6‐Pri3C6H2, Cp° = C5EtMe4)

[Cp°MoCl₄] (Cp° = C₅EtMe₄) reacts with primary phosphines PH₂R to give the paramagnetic phosphine complexes [Cp°MoCl₄(PH₂R)] [Cp° = C₅EtMe₄, R = Bu^t ( 1 ), 1‐Ad (1‐Ad = 1‐adamantyl; 2 ), Cy ( 3 ), Ph ( 4 ), Mes (Mes = 2, 4, 6‐Me₃C₆H₂; 5 ), Tipp (Tipp = 2, 4, 6‐Prⁱ₃C₆H₂; 6 )]. 1 — 6 were characterized spectroscopically (IR, MS), and X‐ray crystal structures were determined for 1 — 4 and 6 . EPR investigations in liquid and frozen solution confirmed the presence of Mo^V species, and the data were used to analyze the spin‐density distribution in the first coordination sphere. Complexes 3 and 4 react with two equivalents of NEt₃ with formation of [Cp°MoCl₂(η³‐P₄Cy₄H)] ( 7 ) and [Cp°₂Mo₂(μ‐Cl)₂(μ‐P₄Ph₄)] ( 8 ), respectively, in low yield. Complexes 7 and 8 were characterized by X‐ray crystallography.     

A double heteroatom Mitsunobu coupling with amino hydroxybenzoic acids on solid phase: a novel application of the Mitsunobu reaction to form dendron building blocks

A new highly efficient double heteroatom Mitsunobu coupling with amino hydroxybenzoic acids on solid phase is described. The synthetic routes reported in this work are general and applicable for the preparation of diverse building blocks, controlling protection, arm length, chirality, and peripheral functional groups. These novel units can form unusual dendritic architectures, which could be incorporated into specific complex structures, expanding the scope of dendrimer science.     

Decorating step-by-step and independently the surface and the core of dendrons

Dendrons possessing one activated vinyl group at the core and several chlorine atoms at the end of the branches are used as starting materials to study the possibility to react independently the surface functions and the core function. In particular, the most powerful sequence of reactions for decorating them by organometallic complexes as end groups and amine or alcohol at the core has been determined. In the first step, phenol phosphines are grafted as end groups of the dendrons, and they can be used for the complexation of metals. However, these phosphines must be kept free when amines are used to react with the vinyl core in the next step. Depending on the type of phosphine end groups and on the type of function of the core (amine or alcohol), the complexation of ruthenium ([RuCl₂(p-cymene)]₂) and rhodium ([RhCl(COD)]₂) derivatives by the phosphine end groups can occur without side reaction at the core.     

Phosphine-mediated diverse reactivity of γ-substituted allenoates with aldehydes: syntheses of highly functionalized chromans and (E,E)-1,3-dienes

As an extension of our previous studies, the phosphine-mediated diverse reactivity of γ-substituted allenoates with aldehydes has been further investigated. Under the catalysis of tris(p-chlorophenyl)phosphine (20 mol %), ethyl 2,3-pentadienoate, namely ethyl γ-methyl allenoate, readily undergoes a formal [4+2] annulation with dual-functional salicylaldehydes, giving highly functionalized chromans in 47-97% yields. This transformation represents a novel reactivity pattern of electron-deficient allenes with aldehydes. Conversely, when the γ substituent in the allenoate changes from methyl to benzyl or the employed phosphine from weakly nucleophilic triarylphosphine to strongly trialkylphosphine, the phosphine-mediated reactivity of γ-substituted allenoates with aldehydes will be steered to a stoichiometric olefination reaction, leading to the highly stereoselective formation of (E,E)-1,3-dienes. Thus, under the mediation of equivalent PPh₃, ethyl γ-benzyl allenoate readily condenses with salicylaldehydes, affording (E,E)-1,3-dienes in 34-84% yields; with strongly nucleophilic 1,3,5-triaza-7-phosphaadamantane (PTA) used instead of PPh₃, ethyl γ-methyl allenoate also gives the corresponding olefination products in 32-73% yields with reactive aromatic aldehydes. On the basis of our previous studies and current work, these chemical transformations of γ-substituted allenoates with aldehydes, as well as their diverse reactivity, have been mechanistically rationalized.