Reactions of isocyanides with rhodium porphyrins: formation of formimidoyl and carbamoyl complexes and CN-R bond cleavage

Poszmik, George; Carroll, Patrick J.; Wayland, Bradford B.

doi:10.1021/om00033a010

Cited by 34 publications

(31 citation statements)

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“…The above results might seem conflicting with reported insertion reactions of CO, olefins, aldehydes, and isocyanides into the RhÀ ÀH bonds of the less hindered complexes [Rh III (OEP)(H)] and [Rh III (TPP)(H)] (141,(143)(144)(145)(146)(147)(148)(149)(150). Since [Rh III (por)(H)] species lack any cis vacant sites, these insertion reactions are quite remarkable and do not likely proceed via a common (migratory) insertion requiring coordination of the CO, CNR, or olefinic substrates cis to the RhÀ ÀH bond.…”

Section: Radicaloid Insertions Into (Por)rhà àH Bondsmentioning

confidence: 67%

The Organometallic Chemistry of Rh‐, Ir‐, Pd‐, and Pt‐Based Radicals: Higher Valent Species

Bruin

Hetterscheid

Koekkoek

et al. 2007

Progress in Inorganic Chemistry

121

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Section: Radicaloid Insertions Into (Por)rhà àH Bondsmentioning

confidence: 67%

The Organometallic Chemistry of Rh‐, Ir‐, Pd‐, and Pt‐Based Radicals: Higher Valent Species

Bruin

Hetterscheid

Koekkoek

et al. 2007

Progress in Inorganic Chemistry

121

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“…All of these results indicate that both electronic and steric properties of the L ligand contribute to the overall trend in binding strengths in the 8Å) of the carbamoyl ligand is similar to that of secondary organic amides, RC(O)NHR′ (1.334 Å), 31 and the CO bond distance (1.217(7) Å) of the carbamoyl ligand is comparable to that of secondary organic amides (1.231 Å). 31 The C(53)−N(7) bond distance (1.355(8) Å) of the carbamoyl ligand is also analogous to that (1.341(5) Å) 20 reported for the pentacoordinate rhodium complex [(OEP)Rh[C(O)NH(C 6 H 3 Me 2 )] and that (1.34(1) Å) 32 for the hexacoordinate ruthenium bis-carbamoyl complex [Ru-(dppe)(CO) 2 [C(O)NHCHMe 2 ] 2 . However, the Ir−N(5) bond distance of 2.208(5) Å in the 1-methylimidazole complex is longer than that reported for Ir−NMe 3 in Ir(TTP)Cl(NMe 3 ) (2.174(2) Å).…”

Section: ■ Results and Discussionmentioning

confidence: 93%

Addition of Amines to a Carbonyl Ligand: Syntheses, Characterization, and Reactivities of Iridium(III) Porphyrin Carbamoyl Complexes

et al. 2014

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Treatment of (carbonyl)chloro(meso-tetra-p-tolylporphyrinato)iridium(III), (TTP)Ir(CO)Cl (1), with excess primary amines at 23 °C in the presence of Na2CO3 produces the trans-amine-coordinated iridium carbamoyl complexes (TTP)Ir(NH2R)[C(O)NHR] (R = Bn (2a), n-Bu (2b), i-Pr (2c), t-Bu (2d)) with isolated yields up to 94%. The trans-amine ligand is labile and can be replaced with quinuclidine (1-azabicyclo[2.2.2]octane, ABCO), 1-methylimidazole (1-MeIm), triethyl phosphite (P(OEt)3), and dimethylphenylphosphine (PMe2Ph) at 23 °C to afford the hexacoordinated carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (for R = Bn: L = ABCO (3a), 1-MeIm (4a), P(OEt)3 (5a), PMe2Ph (6a)). On the basis of ligand displacement reactions and equilibrium studies, ligand binding strengths to the iridium metal center were found to decrease in the order PMe2Ph > P(OEt)3 > 1-MeIm > ABCO > BnNH2 ≫ Et3N, PCy3. The carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = RNH2 (2a,b), 1-MeIm (4a)) undergo protonolysis with HBF4 to give the cationic carbonyl complexes [(TTP)Ir(NH2R)(CO)]BF4 (7a,b) and [(TTP)Ir(1-MeIm)(CO)]BF4 (8), respectively. In contrast, the carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = P(OEt)3 (5a), PMe2Ph (6a,c)) reacted with HBF4 to afford the complexes [(TTP)Ir(PMe2Ph)]BF4 (9) and [(TTP)IrP(OEt)3]BF4 (10), respectively. The carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = RNH2 (2a-d), 1-MeIm (4a), P(OEt)3 (5b), PMe2Ph (6c)) reacted with methyl iodide to give the iodo complexes (TTP)Ir(L)I (L = RNH2 (11a-d), 1-MeIm (12), P(OEt)3(13), PMe2Ph (14)). Reactions of the complexes [(TTP)Ir(PMe2Ph)]BF4 (9) and [(TTP)IrP(OEt)3]BF4 (10) with [Bu4N]I, benzylamine (BnNH2), and PMe2Ph afforded (TTP)Ir(PMe2Ph)I (14), (TTP)Ir[P(OEt)3]I (13), [(TTP)Ir(PMe2Ph)(NH2Bn)]BF4 (16), and trans-[(TTP)Ir(PMe2Ph)2]BF4 (17), respectively. Metrical details for the molecular structures of 4a and17 are reported.

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“…A number of isocyanide complexes have been synthesized and characterized in order to elucidate the nature of the bonding between metal and isocyanides. 17 For metalloporphyrins, isocyanide complexes of iron [18][19][20][21] and rhodium porphyrins 22,23 have been well studied; the crystallographic structures of these complex are the bis[isocyanide] complexes. 19,20,22 The present study revealed that chromium(III) tetraphenylporphyrin forms a 1:1 complex with isocyanide in toluene solutions.…”

Section: Discussionmentioning

confidence: 99%

Laser-Photolysis Studies of Isocyanide Complexes of Chlorochromium(III) Tetraphenylporphyrin in Toluene Solutions

et al. 1998

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Chloroaquachromium(III) tetraphenylporphyrin, Cl(H 2 O)Cr III TPP, reversibly reacts with isocyanide, CN-R, to form Cl(CN-R)Cr III TPP in toluene solutions containing 4.4 × 10 -3 M H 2 O and CN-R. The equilibrium constant for the formation of Cl(CN-R)Cr III TPP obtained by spectroscopic measurements ranges from 10 to 10 2 depending on the nature of the isocyanide used. The laser-photolysis studies of the toluene solution demonstrate that CN-R is photodissociated from Cl(CN-R)Cr III TPP to produce ClCr III TPP with a quantum yield ca. 0.1. The five-coordinate ClCr III TPP reacts with H 2 O and CN-R to give Cl(H 2 O)Cr III TPP and Cl-(CN-R)Cr III TPP, respectively. The transient product Cl(H 2 O)Cr III TPP further reacts with CN-R to regenerate Cl(CN-R)Cr III TPP. The rates for the decay of Cl(H 2 O)Cr III TPP are measured as a function of the concentration of CN-R in order to determine the rate constants of the forward and backward reactions for the formation of Cl(CN-R)Cr III TPP. The equilibrium constants obtained from the kinetic analysis for the decay of Cl-(H 2 O)Cr III TPP are in good agreement with those determined by spectroscopic measurements. The mechanism for the equilibrium reaction is discussed in detail on the basis of the rate constants for the formation of Cl(H 2 O)Cr III TPP and Cl(CN-R)Cr III TPP from ClCr III TPP, measured in the temperature range 200-300 K. The quantum yield for the photodissociation of CN-R is not affected by the presence of oxygen. Since the lowest excited state 6 T 1 of Cl(CN-R)Cr III TPP observed by laser photolysis is effectively quenched by oxygen, this state is not responsible for the ligand ejection from Cl(CN-R)Cr III TPP. The 4 S 1 state is assumed to be the reactive excited state of Cl(CN-R)Cr III TPP.

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Reactions of isocyanides with rhodium porphyrins: formation of formimidoyl and carbamoyl complexes and CN-R bond cleavage

Cited by 34 publications

References 0 publications

The Organometallic Chemistry of Rh‐, Ir‐, Pd‐, and Pt‐Based Radicals: Higher Valent Species

The Organometallic Chemistry of Rh‐, Ir‐, Pd‐, and Pt‐Based Radicals: Higher Valent Species

Addition of Amines to a Carbonyl Ligand: Syntheses, Characterization, and Reactivities of Iridium(III) Porphyrin Carbamoyl Complexes

Laser-Photolysis Studies of Isocyanide Complexes of Chlorochromium(III) Tetraphenylporphyrin in Toluene Solutions

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