Rapid reversible fission of a C–H bond in a metal complex: X-ray crystal structure of [RhHCl(But2PCH2CH2CHCH2CH2PBut2)]

Crocker, Christopher; Errington, R. John; McDonald, Walter S.; Odell, Kevin J.; Shaw, Bernard L.; Goodfellow, R. J.

doi:10.1039/c39790000498

Cited by 93 publications

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“…The amount of the Pd 0 complex did not significantly increase if heating was prolonged (to 20 min). The 31 P coordination chemical shift is similar to the known value for Pd 0 (P(OMe) 3 ) 4 /P(OMe) 3 (∆δ = 21 ppm [26] ) whereas PdCl 2 (P(OEt) 3 ) 2 displays an upfield shift (δ = 92.0, ∆δ = -46 ppm [27] ). On addition of 1a or 2a the Pd 0 complex is no longer detectable by 31 P NMR spectroscopy.…”

Section: Remarks On Mechanistic Aspectssupporting

confidence: 63%

Phosphonylation of 2‐Amino‐ and 2‐Amido‐3‐bromopyridines and 2‐Amino‐3‐chloroquinoxalines with Triethyl Phosphite

Adam¹,

Kindermann²,

Köckerling³

et al. 2009

Eur J Org Chem

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The Tavs reaction of 2-amino-and 2-acylamido-3-bromopyridines 1 and 2 with triethyl phosphite in the presence of palladium acetate or chloride allows the synthesis of 2-aminoand 2-acylamidopyridine-3-phosphonates 3 and 4. A second ring nitrogen atom causes strong activation and leads to excellent yields in the phosphonylation of 2-amino-3-chloroquinoxalines. 2,3-Dichloroquinoxaline does not need a catalyst and undergoes double phosphonylation with sodium diethyl phosphite under Michaelis-Becker conditions. The results show an activating influence of pyridine nitrogen (-M) and deactivating influence of the amino group (+M). The reactivity of 1 and 2 in the Tavs coupling is compared with that of the 3-NH-2-bromopyridine position isomers and 2-bromo-

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Section: Remarks On Mechanistic Aspectssupporting

confidence: 63%

Phosphonylation of 2‐Amino‐ and 2‐Amido‐3‐bromopyridines and 2‐Amino‐3‐chloroquinoxalines with Triethyl Phosphite

Adam¹,

Kindermann²,

Köckerling³

et al. 2009

Eur J Org Chem

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“…The two RhÀP bond lengths are slightly longer than in the related, more symmetrical chelate complex [RhHCl-(tBu 2 PCH 2 C 6 H 3 CH 2 PtBu 2 -k 3 P,C,P)] (18) obtained from RhCl 3 ¥ 3 H 2 O and 1.5-C 6 H 4 (CH 2 PtBu 2 ) 2 in 2-propanol/water under reflux. [16] In contrast, the RhÀC31 bond length of 17 (1.967(5) ä) is slightly shorter than in 18 (1.999(7) ä) and in the related hydrido and methyl complexes [RhHCl{CH(CH 2 CH 2 PtBu 2 ) 2 -k 3 P,C,P}] (2.082(2) ä) [17] and [RhCH 3 Cl{tBu 2 PCH 2 C 6 H-3.5-(CH 3 ) 2 CH 2 PtBu 2 -k 3 P,C,P}] (2.02(2) ä), [18] respectively. The P1-Rh-P2 axis of 17 is significantly bent (160.18 (5)8), which could be due both to steric hindrance between the phosphane substituents and the strain of the chelate ring.…”

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confidence: 78%

Rhodium(I) and Rhodium(III) Complexes Formed by Coordination and CH Activation of Bulky Functionalized Phosphanes

Canepa

Brandt

Ilg

et al. 2003

Chemistry A European J

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The reaction of [[RhCl(C(8)H(14))(2)](2)] (2) with iPr(2)PCH(2)CH(2)C(6)H(5) (L(1)) led, via the isolated dimer [[RhCl(C(8)H(14))(L(1))](2)] (3), to a mixture of three products 4 a-c, of which the dinuclear complex [[RhCl(L(1))(2)](2)] (4 a) was characterized by Xray crystallography. The mixture of 4a-c reacts with CO, ethene, and phenylacetylene to give the square-planar compounds trans-[RhCl(L)(L(1))(2)] (L=CO (5), C(2)H(4) (6), C=CHPh (9)). The corresponding allenylidene(chloro) complex trans-[RhCl(=C=C=CPh(2))(L(1))(2)] (11), obtained from 4 a-c and HC triple bond CC(OH)Ph(2) via trans-[RhCl[=C=CHC(OH)Ph(2)](L(1))(2)] (10), could be converted stepwise to the related hydroxo, cationic aqua, and cationic acetone derivatives 12-14, respectively. Treatment of 2 and [[RhCl(C(2)H(4))(2)](2)] (7) with two equivalents of tBu(2)PCH(2)CH(2)C(6)H(5) (L(2)) gave the dimers [[RhCl(C(8)H(14))(L(2))](2)] (15) and [[RhCl(C(2)H(4))(L(2))](2)] (16), which both react with L(2) in the molar ratio of 1:2 to afford the five-coordinate aryl(hydrido)rhodium(III) complex [RhHCl(C(6)H(4)CH(2)CH(2)PtBu(2)-kappa(2)C,P)(L(2))] (17) by C-H activation. The course of the reactions of 17 with CO, H(2), PhC triple bond CH, HCl, and AgPF(6), leading to the compounds 19-21, 24, and 25 a, respectively, indicate that the coordinatively unsaturated isomer of 17 with the supposed composition [RhCl(L(2))(2)] is the reactive species. Labeling experiments using D(2), DCl, and PhC triple bond CD support this proposal. With either [Rh(C(8)H(14))(eta(6)-L(2)-kappaP]PF(6) or [Rh(C(2)H(4))(eta(6)-L(n)-kappaP]PF(6) (n=1 and 2) as the starting materials, the corresponding halfsandwich-type complexes 27, 28, and 32 were obtained. The nonchelating counterpart of the dihydrido compound 32 with the composition [RhH(2)(PiPr(3))(eta(6)-C(6)H(6))]PF(6) (35) was prepared stepwise from [Rh(C(2)H(4))(PiPr(3))(eta(6)-C(6)H(6))]PF(6) and H(2) in acetone via the tris(solvato) species [RhH(2)(PiPr(3))(acetone)(3)]PF(6) (34) as intermediate. The synthesis of the bis(chelate) complex [Rh(eta(4)-C(8)H(12))(C(6)H(5)OCH(2)CH(2)PtBu(2)-kappa(2)O,P)]BF(4) (39) is also described. Besides 4 a, the compounds 17, 25 a, and 39 have been characterized by Xray crystal structure analysis.

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“…In this respect, pincer ligands with a C−C double bond as a central donating group are interesting since an olefin moiety can interact with the metal atom in several ways, by for example coordination in an η 2 -fashion, oxidative addition of one of the vinylic C−H bonds, or acting as a hydrogen acceptor. A few examples of compounds falling into the formal definition of a pincer complex but with a central alkene group are reported in the literature, 5 but little is known about their properties. A limited number of studies include Bennett's work on some complexes of 2,2′-bis(diphenylphosphino)-trans-stilbene 6 and a recent publication from Iluc 7 about complexation with related 2,2′-bis(di-isopropylphosphino)-trans-stilbene.…”

Section: ■ Introductionmentioning

confidence: 98%

Iridium Pincer Complexes with an Olefin Backbone

Polukeev

Wendt

2015

Organometallics

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Among the large variety of pincer complexes, those with carbon− carbon double bonds in the backbone have received little attention. Here, we report the reactions of complex (PCCP)IrPh (3) and its derivatives with small molecules. Compound 3 readily adds CO to give the 18e adduct (PCCP)IrPhCO (5a), which upon heating undergoes isomerization into the thermodynamically more stable isomer (PCCP)IrCO(Ph) (5b), via reversible loss of CO. Reaction of 5 with hydrogen leads to the formation of saturated carbonyl compounds (PC−CP)IrCO (9) and (PC−CP)IrH(CO)H (10). In contrast to the hydrides (PCCP)IrH 3 (6) and (PC−CP)IrH 4 (7), which are in tautomeric equilibrium via insertion of one of the hydrides into the olefin moiety, the former compounds do not isomerize into the olefin form. Protonation of 5 with CF 3 COOH gives a complex with an agostic methylene group, 11, which undergoes a rare transformation for Ir pincers, which is insertion of CO into the Ir−Ph bond with subsequent formation of (PCCP)IrOCOCF 3 (12) and Ph−CHO. The trihydride 6 reacts with CO to give 9, which can add a second molecule of CO to reversibly form the dicarbonyl 13.

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Rapid reversible fission of a C–H bond in a metal complex: X-ray crystal structure of [RhHCl(Bu^t₂PCH₂CH₂CHCH₂CH₂PBu^t₂)]

Cited by 93 publications

References 0 publications

Phosphonylation of 2‐Amino‐ and 2‐Amido‐3‐bromopyridines and 2‐Amino‐3‐chloroquinoxalines with Triethyl Phosphite

Phosphonylation of 2‐Amino‐ and 2‐Amido‐3‐bromopyridines and 2‐Amino‐3‐chloroquinoxalines with Triethyl Phosphite

Rhodium(I) and Rhodium(III) Complexes Formed by Coordination and CH Activation of Bulky Functionalized Phosphanes

Iridium Pincer Complexes with an Olefin Backbone

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