Preparation, Structure, and Reactivity of New Bis(acetylide) and Acetylide-Vinylidene Ruthenium(II) Complexes Stabilized by Phosphite Ligands

Abstract

Bis(alkyny1) complexes Ru(CWR12P4 (1-3) (R = Ph,p-tolyl, tBu; P = P(OMe)3 (11, P(OEt)3 (2), PPh(0Et)z (3)) were prepared by reacting RuCl2P4 with excess Lif RC=C-, and a trans geometry was established both in solids (X-ray) and in solution. The reaction of these alkynyls (1 -3) with electrophilic reagent depends on the nature of the phosphite ligand. Vinylidene-acetylide derivatives [RU(CGCR){=C=C(R~)R}P~I+ (R1 = H (4, 51, CH3 (7, 8), ArN-N (lo), I (12), 2,3-(No~)&&S (14)) were prepared with P(OMe)3 and P(OEt)3 ligand by treatment of 1 and 2 with HBF4, CF3S03Me, ArNz+BF4-, Iz, and ~,~-( N O Z ) Z C~H~S C~, respectively. Instead, only the diazo-and iodovinylidenes [Ru(CsCR){ =C=C(R1)R)P41f (RI = p-tolN-N (ll), I (13)) were obtained with the PPh(0Et)z phosphite ligand. These vinylidene compounds were fully characterized by IR, IH, 31P, and 13C NMR spectra, and a single-crystal X-ray structure determination of complex [Ru(C=CPh){=C=C(Me)Ph}-{P(OEt)3}4]CF3S03 (8a) is reported. The alkynyl-vinylidene [Ru(C=CR){=C=C(H)R}P4]+ cations (4, 5) rearrange in solution to enynyl [Ru(q3-RC3CHR)P41f derivatives, and the reaction is inhibited by the presence of free alkyne. Kinetic data support a mechanism involving a pentacoordinate intermediate formed by loss of the vinylidene ligand. Substitution of the =C=C(H)R ligand by phosphite, isocyanide, and nitrile is easy in 4 and 5 and leads to [Ru(C~CPh){P(OMe~3}P41+ -(17), tolCN)2P4l2+ (19) (P = P(OEt)3), derivatives. ligand in 4 and 5, giving Ru(C=CR)zP4, was Introduction A large number of studies on the chemistry of transi-

Solvent and phosphine dependency in the reaction of cis-RuCl2(P–P)2 (P–P=dppm or dppe) with terminal alkynes

“…Several other examples of the dimerisation of alkynes within the coordination sphere of ruthenium to give g 3 [10]. Other routes to generate these species include the reaction of RuClH(Cyttp) with PhC"CAC"CPh to give anti-mer and syn-mer-[RuCl(g 3 -PhAC"CAC@CHPh) (Cyttp)] whereas reaction of RuH 4 (Cyttp) [Cyttp = PhP(CH 2 CH 2 CH 2 P{c-C 6 H 11 } 2 ) 2 ] with PhC"CH affords [Ru(-C"CPh)(g 3 -Ph-C"CAC@CHPh)(Cyttp)] [11,12].…”

“…A related compound containing butenynyl and alkynyl ligands, anti-mer-[Ru(-C"CPh)(g 3 -Ph-C"CAC@CHPh)(PNP)], may be prepared from the reaction of mer, trans-[RuCl 2 (@C@CHPh)(PNP)] [PNP = Pr n N(CH 2 CH 2 PPh 2 ) 2 ] with an excess of LiC"CPh [13]. Several of these compounds have had their structures determined by single crystal X-ray diffraction [9][10][11][12][13] and the topology of the butenynyl ligand in 3a is similar to that observed in the related complexes. The reaction to form 3a from cis-[RuCl 2 (dppm) 2 ], 2 equiv.…”

Unsymmetrically Substituted Butenynyl‐Iron(II) Complexes

“…[3,9] In a manner similar to the homodimerisation of alkynes, metal-catalysed cross-coupling reactions could involve the intermediacy of unsymmetrically 1,4-disubstituted butenyne metal complexes When used as a ligand, the but-1-en-3-yn-2-yl moiety can coordinate in either an η 3 -or η 1 -mode, depending on the co-ligands and metal centre, and the η 1 -coordination mode of butenynyl ligands has been implicated as an important intermediate preceding σ-bond metathesis with alkynes during the metal mediated coupling of alkynes. [10] Butenynyl complexes have been studied for a range of transition metals including iron, [11][12][13][14] ruthenium, [2,5,10,[15][16][17][18] osmium, [19] and platinum. [20] Various methods have been established for the synthesis of butenynyl complexes, including the addition of 1,4-disubstituted-1,3-diynes to metal hydride complexes, [2,15,21] and the addition of terminal acetylenes to either metal hydrides, [2,13,22,23] metal acetylides, [1,17,24] or metal alkenyl complexes.…”

Reactions of Hydride Complexes of Ruthenium and Osmium with Propargylic Alcohols: Preparation of Chelate Vinyl ­Derivatives

“…Reaction of these pentacoordinate complexes with alkynes gives the final enynyl derivatives 5 and 6. Support for this reaction path comes both from our previous studies in this field [9,23] and from the presence, in the 1 H NMR spectra of the reaction mixture, of a multiplet between 5.8 and 5.0 ppm, which is characteristic of alkene [A]. The reaction therefore indicates that our chelate vinyl ligand C(=CH 2 )CPhR(OH) may be removed from the coordination sphere of a metal by reaction with a terminal alkyne to yield enynyl [M]-η 3 -R 1 C 3 C(H)R 1 derivatives as a final product.…”