Protonation and H₂ Heterolysis Reactions of Electrophilic (η⁵-C₅R₅)Ru(dfepe)(X) (R = H, Me; X = H, OTf) Complexes

Abstract

Addition of excess HOSO2CF3 (HOTf) to CpRu(L)H (1) (L = dfepe = PR2CH2CH2PR2, R = C2F5) in CD2Cl2 under N2 produces a mixture of [CpRu(L)(H)2]+ (2a), [CpRu(L)(H2)]+ (2b), and CpRu(L)(OTf) (3) in a ratio of 1:5:2. Salts of the acid [HOEt2]+ are not strong enough to protonate 1. Complexes 2 slowly eliminate H2 to give 3; this reaction is slowed by adding excess HOTf. Of all such complexes [CpRu(PR2CH2CH2PR2)(H2)]+, R = alkyl and aryl, the dihydrogen complex 2b has the greatest acidity (similar to that of HOTf) and the related HD complex has the greatest J HD (29.1 Hz) because of the electron-withdrawing substituents R = C2F5. The reaction of 3 with 1 atm H2(g) proceeds much faster in the presence than in the absence of 1 equiv of HOTf to produce 1 and HOTf. This is a rare example of the production of a strong acid from H2(g) where the intermediate dihydrogen complex has been characterized. Reaction of Cp*Ru(L)Cl (4), Cp* = C5Me5, in dry CH2Cl2 at −78 °C with AgX salts under H2(g) (1 atm) gives mixtures of Cp*Ru(L)H (5) and [Cp*Ru(L)(H)2]+ (6), which have been identified by 1H NMR. 6 is deprotonated by traces of water or by PPh3 to give Cp*Ru(L)H (5). The addition of excess HOTf to mixtures of 5 and 6 under H2(g) produces 6. Complexes 3, 4, and 5 have been characterized by single-crystal X-ray diffraction. Complexes CpRu(L)Cl, 1, 4, and 5 have very positive redox potentials that indicate that the dfepe ligand has the electron-withdrawing power close to that of two carbonyl ligands.

Trifluoromethanesulfonate (triflate) as a moderately coordinating anion: Studies from chemistry of the cationic coordinatively unsaturated mono- and diruthenium amidinates

“…5.27. Found: C,45.13;H,4.79;N,5.43%. 1 H NMR (600 MHz, CD 2 Cl 2 ) d 1.12 (br, 12H, CHMe 2 ), 2.97 (sep, J = 6.2 Hz, 2H, CHMe 2 ), 5.81 (s, 6H, g 6 -C 6 H 6 ), 6.99 (br, 2H, Ph), 7.35 (br, 3H, Ph).…”

Pentamethylcyclopentadienyl rhodium(III) trifluorovinyl phosphine complexes and attempted intramolecular dehydrofluorinative coupling of pentamethylcyclopentadienyl and trifluorovinyl phosphine ligands

“…The identities of the complexes were confirmed by single-crystal X-ray diffraction studies (Figs. [1][2][3]. Crystallographic data are presented in Table 2.…”

“…In contrast to fluorinated aryl and alkyl phosphines [1][2][3][4][5][6][7][8][9][10], fluoroalkenylphosphines have received relatively little attention [11][12][13]. Following the development of a convenient synthetic route to [CF 2 CF] À Li + from the readily available HFC-134a (CF 3 CH 2 F), and subsequent syntheses of trifluorovinylphosphines R 3Àx P(CF CF 2 ) x [14][15][16], a number of complexes of trifluorovinylphosphines with molybdenum [15], platinum [15,17] and gold [15] have been reported over the past decade.…”

Synthesis, characterization, and crystal structures of the osmium triflate complexes Cp∗Os(P–P)(OTf) and [Cp∗Os(P–P)(OH2)][OTf]

“…In comparison, the reported Os-P bond distances for the related cation [Cp * Os(dppm)H 2 ] + are both 2.312(1) Å [23]. The crystal structure of the corresponding CpRu-(dfepe)(OTf) complex (dfepe = 1,2-bis[bis(pentafluoroethyl)phosphino]ethane) is also known [13]. Efforts to distinguish the anhydrous and the aquated triflate complexes from differences in the NMR chemical shifts were thwarted because often there was no solvent in which both kinds of species were soluble without reacting.…”

“…For the platinum metals, this route has been used to prepare triflate complexes of Ru [2][3][4], Os [5,6], Rh [7], Ir [8], and Pt [9][10][11]. Formation of triflate complexes by addition of triflic acid to metal hydrides (with loss of H 2 ) is also possible; all the examples of this approach of which we are aware involve the element Ru [12][13][14].…”