(p-cymene)Ruthenium(II)(diphenylphosphino)alkyne Complexes:  Preparation of (μ-Cl)(μ-PPh₂C⋮CR)-Bridged Ru/Pt Heterobimetallic Complexes

Abstract

The neutral complexes [(η6-p-cymene)RuCl2(PPh2C⋮CR)] (R = Ph 1, tBu 2, (4-CH3)C6H4 3, (4-C⋮CPh)C6H4 4, (4-CN)C6H4 5) have been synthesized by reacting [(p-cymene)RuCl2]2 with the respective alkynylphosphine. Treatment of 1−5 with AgOTf or TlPF6 and the corresponding PPh2C⋮CR allows the preparation of cationic bis(diphenylphosphino) compounds [(η6-p-cymene)RuCl(PPh2C⋮CR)2]X (X = OTf; R = Ph 6, tBu 7, (4-CH3)C6H4 8, (4-C⋮CPh)C6H4 9, X = PF6; R = (4-CN)C6H4 10). All complexes have been characterized by analytical and spectroscopic methods, by cyclic voltammetry, and in several cases (3 and 7) by X-ray crystallography. Reactions of both neutral (1−4) and cationic (6−8) complexes with [cis-Pt(C6F5)2(thf)2] (thf = tetrahydrofuran) gave heterobimetallic neutral [(η6-p-cymene)ClRu(μ-Cl)(μ-1κP:η2-PPh2C⋮CR)Pt(C6F5)2] (R = Ph 11a, tBu 12a, (4-CH3)C6H4 13a, (4-C⋮CPh)C6H4 14a) and cationic [(η6-p-cymene)(PPh2C⋮CR)Ru(μ-Cl)(μ-1κP:η2-PPh2C⋮CR)Pt(C6F5)2](OTf) (R = Ph 15, tBu 16, (4-CH3)C6H4 17) derivatives stabilized by a mixed Cl/PPh2C⋮CR bridging system. The molecular structures of 12a and 17 have been confirmed by X-ray diffraction. However, the neutral complexes 11−14 existed in solution as a mixture of isomers [(η6-p-cymene)ClRu(μ-Cl)(μ-1κP:η2-PPh2C⋮CR)Pt(C6F5)2] (a) and [(η6-p-cymene)(PPh2C⋮CR)Ru(μ-Cl)2Pt(C6F5)2] (b), respectively.

Rhenium carbonyl compounds with (diphenyl)phosphinoalkynes and a sterically hindered phosphinoalkyne

“…In all cases a main compound was formed, which displayed a sole signal in the 31 P NMR spectra between À24/ À27 ppm with the characteristic shift to low field respect to free ligands (À32/À34 ppm) after coordination of the phosphorus atom to the metal. The IR spectra in the m(CO) region also is consistent with this hypothesis since in all cases an intense signal is observed around 2175 cm À1 , assigned to the uncoordinated alkyne [4,7,11,12] and three bands characteristic of the fac-{Re(CO) 3 } + fragment [23a,25]. Unfortunately, all attempts to isolate complexes 1-3 in solid state led to compounds contaminated with [NEt 4 ]Br, which is formed in the substitution reaction of bromide by the phosphine (Scheme 2).…”

“…The 13 C NMR spectra of complexes 1-3 also supply relevant information in agreement with the proposed structure since in all cases two doublets can be observed in the 70-120 ppm region assigned to the two acetylenic carbons. The shift observed respect to the free ligands and the increase in the J P-C coupling constants is characteristic of P-coordinated phosphinoalkynes [3,4,7,11,12].…”

“…The first studies in the 1980s were focused on their capacity to support polynuclear metal clusters by means of phosphido and alkynyl fragments, which were formed after P-C bond cleavage [1]. However, further studies with a broad range of metal complexes have revealed other interesting abilities of these ligands such as the preparation of metal complexes with uncoordinated alkynes [2][3][4], intramolecular coupling of the alkynyl moieties [5][6][7], insertion of the triple bond in M-H or M-C bonds [8,9], preparation of heterometallic compounds [6,[10][11][12], or the development of new materials [13]. These ligands can also lead to the formation of metallacycles by means of a reaction between the alkyne and another ligand linked to metal [9,14,15].…”

Ethynyltolan Platinum Complexes with (Arylalkynyl)phosphane Ligands

“…, which can be related to the triplebond polarisation, [9,13,59,60] is similar in both complexes [∆ = 28.5 (2) and 24.7 ppm (3)]. …”

“…Elemental analyses were carried out with a Perkin-Elmer 2400 CHNS/O microanalyzer and mass spectra were recorded with a VG Autospec spectrometer (FAB + ) or a Microflex MALDI-TOF Bruker spectrometer operating in the linear and reflector modes using dithranol as the matrix. HCϵCC 6 H 4 CϵCPh, [86] PPh 2 CϵCtol, [87] PPh 2 CϵCC 6 H 4 Cϵ CPh [13] and cis-[Pt(C 6 F 5 )(thf) 2 ] [88] were prepared according to published procedures. Figure 3 shows the labelling scheme for the carbon atoms in the ethynyltolan ligand and in the (ethynyltolan)diphenylphosphane ligand.…”