Controlled stepwise reaction of a geminal substituted alkene or primary amine group afforded a small library of new functionalised tertiary and ditertiary phosphines. Accordingly, Mannich based ...condensation of the commercially available disubstituted arene C6H4(NH2){2-C(Me)=CH2} with HOCH2PR2 (R2 = Cg: 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantyl; Ph2) afforded the (aminomethyl)phosphines C6H4(NHCH2PCg){2-C(Me)=CH2} L1 and C6H4(NHCH2PPh2){2-C(Me)=CH2} L2 in approx. 60% yield. In addition to the formation of L2, the diphosphine L3 was also identified and independently synthesised upon reaction of C6H4(NH2){2-C(Me)=CH2} with two equiv. of HOCH2PPh2 in CH3OH under reflux. Alternatively, reaction of C6H4(NH2){2-C(Me)=CH2} with H-PR2 (R2 = Cg or Ph2) in the presence of AIBN 2,2′-azobis(2-methylpropionitrile) as free radical initiator, afforded the primary amine functionalised phosphines C6H4(NH2){2-CH(Me)CH2PCg} L4 and C6H4(NH2){2-CH(Me)CH2PPh2} L5 in 85% and 66% isolated yields respectively. In both cases only the anti-Markovnikov addition products were observed. Subsequent reaction of L5 with HOCH2PR2 (R2 = Ph2) afforded the unsymmetrical ditertiary phosphine C6H4(NHCH2PPh2){2-CH(Me)CH2PPh2} L6. Some preliminary coordination studies towards RuCl(μ-Cl)(η6-C10H14)2, AuCl(tht) (tht = tetrahydrothiophene) and MCl2(η4-cod) (M = Pd, Pt; cod = cycloocta-1,5-diene) demonstrate these new ligands behave as classic P-donors leaving the pendant amino or alkenyl groups non-coordinating. All compounds have been characterised by multinuclear NMR, FT−IR, mass spectrometry and microanalysis. Single crystal X-ray studies have been performed on L3, L5, L6, 1, 3b·0.5CH2Cl2, 4a·1.5CH2Cl2, 5 and 6·0.5CDCl3·0.5C4H10O.
•One-step synthesis of tertiary and ditertiary phosphines bearing an olefinic or primary amine group.•A study of their ligating potential towards RuII, PdII, PtII and AuI metal centres.•P-monodentate or P,P-bridging behaviour observed for the new phosphine ligands.•Structures verified in solution using NMR (1H, 31P) spectroscopy.•Single crystal X-ray crystallography confirmed solid state structures in eight cases.
A series of bulky phosphine ligands bearing terphenyl substituents (PR2Ar′) has been prepared, characterized, and used for the synthesis of some coordination compounds of Rh(I), Ir(I), and Pt(II). ...While the expected κ1-P coordination mode is found for rhodium and iridium species, the dichloride phosphine Pt(II) derivative obtained by reaction of PtCl2 with PMe2ArDipp2 exhibits a bidentate κ1-P, η1-arene coordination mode. Display omitted
A series of sterically demanding aryl phosphine ligands (L) bearing terphenyl substituents, PR2Ar′ (R=hydrocarbyl, Ar′=2,6-diarylphenyl radical) has been prepared and characterized. The stability of these ligands towards oxidation in the air has been tested, and theoretical and experimental studies aimed to provide information on their electronic and steric properties have been performed. Treatment of the metal dimers MCl(COD)2 (M=Rh, Ir; COD=1,5-cyclooctadiene) with ligands PMe2ArXyl2 (L1) and PMe2ArDipp2 (L5), in a 1:1 metal:ligand ratio, afforded the expected square-planar 16-electron complexes MCl(COD)(PMe2ArXyl2) and MCl(COD)(PMe2ArDipp2), respectively. These compounds were readily converted into the corresponding dicarbonyl derivatives, MCl(CO)2(PMe2ArXyl2) and MCl(CO)2(PMe2ArDipp2), respectively. While the expected κ1-P coordination mode of the PR2Ar′ ligands is found for these rhodium and iridium species, the mononuclear Pt(II) derivative obtained by reaction of PtCl2 with PMe2ArDipp2 has composition PtCl2(PMe2ArDipp2), and exhibits a bidentate κ1-P, η1-arene coordination mode involving one of the ipso carbon atoms of a flanking terphenyl aryl ring. The corresponding carbonyl compound PtCl2(CO)(PMe2ArDipp2), was generated under a CO atmosphere and exhibits κ1-P coordination mode.
The one‐step synthesis (44 % isolated yield) of the 1,5‐benzodiazapine functionalised phosphine 1, C31H31N2OP, is reported. Bridge cleavage of {MCl(μ‐Cl)(η5‐Cp*)}2 (M=Ir, Rh) with 2 equiv. of 1 in ...CH2Cl2 gave the mononuclear compounds MCl2(η5‐Cp*)(P‐1) (M=Ir, 2 a; M=Rh, 2 b) in which 1 functions as a P‐monodentate ligand. Rapid C(sp3)−H bond activation, at room temperature, is observed for 2 a leading to the unusual cyclometallated complex Ir(η5‐Cp*)(P,N,C‐1)Cl2 3 (or 3‘) bearing an anionic P/Namine/C‐terdentate ligand. Reaction of Pt(CH3)Cl(η4‐cod) with one equiv. of 1 led to Pt(CH3)Cl(P,N‐1) 4, suggesting that 3 may form via an intermediate IrIII cationic species in which the ligand is P,N‐bound. The IrI complex IrCl(η4‐cod)(P‐1) 5 does not, under similar conditions, show any evidence for C−H activation. Single crystal X‐ray studies on 1, 2 a, 2 b, 3, 3‘, 4, and 5 reveal intramolecular N ⋅⋅⋅ H−O H‐bonding in all cases.
Mild C(sp3)−H activation of an IrIII phosphine functionalised 1,5‐benzodiazapine affords selectively an unusual cyclometallated piano‐stool complex bearing an anionic P/Namine/C‐terdentate ligand. The facile synthesis of the new functionalised tertiary phosphine, and its coordination chemistry to Ir(I), Ir(III), Rh(III) and Pt(II), are reported.
The synthesis of three new trisubstituted tertiary phosphines bearing 1-aminonaphthyl groups is reported along with a survey of their coordination capabilities at various RuII, IrIII, PdII, PtII and ...AuI metal centres. Various inter- and intramolecular H-bonding and X⋯X contacts have been identified using single crystal X-ray crystallography.
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•Two-step synthesis of three new trisubstituted tertiary phosphines bearing 1-aminonaphthyl groups.•A study of their ligating potential towards RuII, IrIII, PdII, PtII and AuI metal centres.•Structures verified in solution using NMR (1H, 31P) spectroscopy.•Single crystal X-ray crystallography confirmed solid state structures in seven cases.•Different inter/intramolecular H-bonding motifs observed.
The two-step synthesis of new naphthyl based P{CH2-1-NHC10H6(4-R)}3 ligands (R=H, L1; R=Cl, L2; R=Br, L3) by initial condensation of P(CH2OH)4Cl with 4equiv of 1-NH2C10H6(4-R) in EtOH, followed by reduction with tBuOK in MeOH, is described. Oxidation of L1 with elemental S or grey Se gave SP{CH2-1-NHC10H6(4-H)}3SL1 or SeP{CH2-1-NHC10H6(4-H)}3SeL1 respectively. The two-coordinate Au(I) complex AuCl(L1) 4 was prepared from AuCl(tht) (tht=tetrahydrothiophene) and one equiv. of L1 in 83% yield. Chloro-bridge cleavage of RuCl(μ-Cl)(η6-C10H14)2 or IrCl(μ-Cl)(η5-Cp∗)2 with L1, in CH2Cl2, gave the mononuclear complexes RuCl2(η6-C10H14)L1 5 and IrCl2(η5-Cp∗)L1 6 respectively. Similarly chloro-bridge cleavage of the cyclometallated compounds Pd(μ-Cl)(κ2-C6H4CH2NMe2)2 or Pd(μ-Cl)(κ2-C10H6NMe2)2 with L1–L3 gave the κ2-PN-chelate complexes PdCl(κ2-C6H4CH2NMe2)L1–L3 (8–10) or PdCl(κ2-C10H6NMe2)L1 11 respectively. Reaction of two equiv. of L1–L3 with PtCl2(cod) (M=Pt, cod=cycloocta-1,5-diene), in CH2Cl2, afforded the complexes MCl2(L1–L3)2 (11–13) as the cis isomers. In contrast, reaction of two equiv. of L1 with PdCl(CH3)(cod) gave PdCl(CH3)(L1)2 14 exclusively as the trans isomer. All compounds have been characterised by multinuclear NMR, FT-IR, mass spectrometry and microanalysis. Single crystal X-ray studies have been performed on compounds L1, 4, 6·CDCl3·OEt2, 8–10 and 11·CDCl3·OEt2. Intermolecular and/or intramolecular H-bonding is observed in various instances involving the secondary amine groups.
The solid-state behaviour of two series of isomeric, phenol-substituted, aminomethylphosphines, as the free ligands and bound to PtII, have been extensively studied using single crystal X-ray ...crystallography. In the first library, isomeric diphosphines of the type Ph2PCH2N(Ar)CH2PPh2 1a–e; Ar = C6H3(Me)(OH) and, in the second library, amide-functionalised, isomeric ligands Ph2PCH2N{CH2C(O)NH(Ar)}CH2PPh2 2a–e; Ar = C6H3(Me)(OH), were synthesised by reaction of Ph2PCH2OH and the appropriate amine in CH3OH, and isolated as colourless solids or oils in good yield. The non-methyl, substituted diphosphines Ph2PCH2N{CH2C(O)NH(Ar)}CH2PPh2 2f, Ar = 3-C6H4(OH); 2g, Ar = 4-C6H4(OH) and Ph2PCH2N(Ar)CH2PPh2 3, Ar = 3-C6H4(OH) were also prepared for comparative purposes. Reactions of 1a–e, 2a–g, or 3 with PtCl2(η4-cod) afforded the corresponding square-planar complexes 4a–e, 5a–g, and 6 in good to high isolated yields. All new compounds were characterised using a range of spectroscopic (1H, 31P{1H}, FT–IR) and analytical techniques. Single crystal X-ray structures have been determined for 1a, 1b∙CH3OH, 2f∙CH3OH, 2g, 3, 4b∙(CH3)2SO, 4c∙CHCl3, 4d∙½Et2O, 4e∙½CHCl3∙½CH3OH, 5a∙½Et2O, 5b, 5c∙¼H2O, 5d∙Et2O, and 6∙(CH3)2SO. The free phenolic group in 1b∙CH3OH, 2f∙CH3OH,2g, 4b∙(CH3)2SO, 5a∙½Et2O, 5c∙¼H2O, and 6∙(CH3)2SO exhibits various intra- or intermolecular O–H∙∙∙X (X = O, N, P, Cl) hydrogen contacts leading to different packing arrangements.
The ferrocene titration method has been employed to determine the one‐electron reduction potentials of a series of oxido‐iron(IV), oxido‐cobalt(IV) and oxido/hydroxido‐nickel(III) complexes based on ...the same tetradentate TMG3tren ligand (TMG3tren=tris2‐(N‐tetramethylguanidyl)ethylamine). The S=2 ground state of the (TMG3tren)FeIV=O2+ complex allows an exchange enhanced reactivity, which enables it to perform efficient oxygen atom transfer (OAT) and hydrogen atom ion (HAA) reactions with a low one‐electron reduction potential of 270 mV vs. SCE. In the absence of exchange enhanced reactivity, the OAT and HAA abilities of the S=3/2 (TMG3tren)CoIV−O(Sc(OTf)3)2+, S=1/2 (TMG3tren)NiIII−O(H)2+ and the previously reported S=1 (TMC)(CH3CN)FeIV=O2+ and (N4Py)FeIV=O2+ complexes can be directly correlated to their reduction potentials. Notably, (N4Py)FeIV=O2+ and (TMG3tren)FeIV=O2+ exhibit similar OAT and HAA reactivities although the reduction potential of (N4Py)FeIV=O2+ is 0.24 V more positive than that of (TMG3tren)FeIV=O2+. The present study therefore provides experimental evidence for exchange enhanced reactivity and rationalizes nature's choice for employing S=2 oxido‐iron(IV) cores to achieve difficult oxidation reactions at biologically viable potentials.
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