Isomerism in complexes of bidentate ligands with enantiotopic donor atoms

Tapscott, Robert E.; Mather, J. D.; Them, Theodore F.

doi:10.1016/s0010-8545(00)82108-6

Cited by 14 publications

(6 citation statements)

References 216 publications

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“…NMR: 1.53 (d, 9 H, VPH = 9.2 Hz, PMe}), 2.19 (d, 6 H, VPH = 9.0 Hz, PMe), 7.15-7.92 (m, 14 H, aromatics). 3IP['H| NMR: -7.0 (t, 1 P, VPP = 6.3 Hz, PMe3), 34.3 (d, 2 P, 2JPP = 6.3 Hz, PMe).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R,S)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R,S)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Rahman¹,

Salem²,

Stephens³

et al. 1990

Inorg. Chem.

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Section: Methodsmentioning

confidence: 99%

“…The following compounds were prepared similarly. NMR: 0.53 (d, 9 H, VPH = 9.4 Hz, PAfe3), 1.46 (d, 3 H, 2,/Ph = 9.1 Hz, PMe), 2.41 (d, 3 H, VPH = 8.6 Hz, PMe), 7.16-7.74 (m, 14 H, aromatics). 31P|'H| NMR: -8.5, 37.7, 38.9 (ABX, 3 P, |VPP| = 7.9 Hz, |VPP| = 3.7 Hz, |27PP| = 4.9 Hz).…”

Section: Methodsmentioning

confidence: 99%

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R,S)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R,S)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Rahman¹,

Salem²,

Stephens³

et al. 1990

Inorg. Chem.

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“…Thus, ( R *, S *)-tetraphos can form head-to-head ( H , H ) and head-to-tail ( H , T ) diastereomers of complexes of the type [M 2 {( R *, S *)-tetraphos} 2 ]. To form these diastereomers it is necessary only that there be no performable symmetry operation (a proper rotation) relating the inner and outer pairs of donor groups …”

Section: Resultsmentioning

confidence: 99%

“…[4][5][6] Here we describe our findings concerning the selfassembly of double-stranded disilver To form these diastereomers it is necessary only that there be no performable symmetry operation (a proper rotation) relating the inner and outer pairs of donor groups. 8 Ligands that fall within this category are henceforth referred to as meso or R*,S* tetradentates and are designated A-R-S-A to distinguish them from their constitutionally unsymmetrical A-B-C-A counterparts, which have no symmetry element relating the donor atoms or groups. The A-R-S-A ligands can generate isomeric complexes one-for-one but not necessarily in symmetry with those formed by A-B-C-A ligands.…”

Section: Introductionmentioning

confidence: 99%

Diastereoselectivity and Molecular Recognition in the Self-Assembly of Double-Stranded Dinuclear Metal Complexes of the Type [M₂{(R,S)-tetraphos}₂](PF₆)₂ (M = Ag and Au)

et al. 2003

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The ligand (R,S)-Ph(2)PCH(2)CH(2)P(Ph)CH(2)CH(2)P(Ph)CH(2)CH(2)PPh(2), (R,S)-tetraphos, combines with silver(I) and gold(I) ions in the presence of hexafluorophosphate to diastereoselectively self-assemble the head-to-head (H,H) diastereomers of the double-stranded, dinuclear metal complexes [M(2)[(R,S)-tetraphos](2)](PF(6))(2) in which the two chiral metal centers in the complexes have M (R end of phosphine) and P (S end of phosphine) configurations. The crystal and molecular structures of the compounds have been determined: (H,H)-(M,P) -[Ag(2)[(R,S)-tetraphos](2)](PF(6))(2), monoclinic, P2(1)/c, a = 10.3784(2), b = 47.320(1), c = 17.3385(4) A, beta = 103.8963(5) degrees, Z = 4; (H,H)-(M,P)-[Au(2)[(R,S)-tetraphos](2)](PF(6))(2), monoclinic, P.2(1) (No. 4, c unique axis), a = 24.385(4), b = 46.175(3), c = 14.820(4) A, Z = 8. The complexes crystallize as racemic compounds in which the unit cell in each case contains equal numbers of enantiomorphic molecules of the cation and associated anions. The cations in both structures have similar side-by-side structures of idealized C(2) symmetry, the bulk helicity of each molecule in the solid state being due solely to the twist of the central ten-membered ring containing the two metal ions of opposite configuration, which has the chiral twist-boat-chair-boat conformation. When 1 equiv each of (R,S)-tetraphos, (R,R)-(+/-)-tetraphos, (S,S)-(+)-tetraphos, 2 equiv of Ph(2)PCH(2)CH(2)PPh(2) (dppe), and 7 equiv of [AuCl(SMe(2))] in dichloromethane are allowed to react for several minutes in the presence of an excess of ammonium hexafluorophosphate in water (two phases), the products are the double-stranded digold(I) complexes in which each ligand strand has recognized itself by stereoselective self-assembly, together with [Au(dppe)(2)]PF(6).

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“…The separation of the meso isomer from the two enantiomeric forms was accomplished by fractional crystallization from ethanol in which the meso dihydrochloride is less In a typical experiment, 1 mmol of [PtCl2(DMSO)2] suspended in methanol (40 mL) was treated with 1 mmol of free amine in the same solvent (20 mL) and stirred until a clear solution was formed. After being cooled to 5 °C and filtered, the solution was concentrated under vacuum and the residue treated with an aqueous solution of lithium chloride to separate a yellow solid, which was a mixture of isomers (1-3, starting from (R,R)-ethambutol; 4-6 starting from (5,5)-ethambutol; and 7-10 starting from (Ry$)-ethambutol; Chart I). If the solid and the mother liquor are heated to 80 °C for 5 h and then cooled to room temperature, the precipitate that is left is observed to be a pure single isomer in the case of (RJt)and (SyS)-ethambutol (isomers 1 and 4 of Chart I, respectively) but still a mixture of isomers in the case of (R,-S)-ethambutol.…”

Section: Methodsmentioning

confidence: 99%

Steric constraints inside the metal-coordination sphere as revealed by diastereotopic splitting of methylene protons

Giannini¹,

Natile²

1991

Inorg. Chem.

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A solution NMR study performed on [PtCl2(ethambutol)] [ethambutol = ,1 -\ %( 1 -hydroxy-2-butyl)ethylenediamine] has shown that the nitrogen substituents [-CH(CH2OH)(CH2CH3)] conform themselves so as to direct the least bulky side (the tertiary hydrogen atom) toward the cis chlorine ligand, and this appears to be the most compelling steric requirement. As a consequence, the hydroxymethyl and ethyl radicals (R) are directed one inward and the other outward with respect to the chelating moiety. The radical directed toward the chelate ring deeply interacts with it, and as a consequence, the methylene protons of this radical exhibit, in the NMR spectrum, a diastereotopic splitting the average value of which is 0.45 ppm in the case of hydroxymethyl and 0.80 ppm in the case of ethyl.

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Isomerism in complexes of bidentate ligands with enantiotopic donor atoms

Cited by 14 publications

References 216 publications

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R,S)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R,S)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R,S)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R,S)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Diastereoselectivity and Molecular Recognition in the Self-Assembly of Double-Stranded Dinuclear Metal Complexes of the Type [M₂{(R,S)-tetraphos}₂](PF₆)₂ (M = Ag and Au)

Steric constraints inside the metal-coordination sphere as revealed by diastereotopic splitting of methylene protons

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Isomerism in complexes of bidentate ligands with enantiotopic donor atoms

Cited by 14 publications

References 216 publications

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R*,S*)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R*,S*)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R*,S*)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R*,S*)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Diastereoselectivity and Molecular Recognition in the Self-Assembly of Double-Stranded Dinuclear Metal Complexes of the Type [M2{(R*,S*)-tetraphos}2](PF6)2 (M = Ag and Au)

Steric constraints inside the metal-coordination sphere as revealed by diastereotopic splitting of methylene protons

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Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R,S)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R,S)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Stability and stereochemistry of tetrahedral nickel nitrosyl complexes: crystal and molecular structures of (R,S)-anti-[NiNCS(NO){1,2-C6H4(PMePh)2}] and (R,S)-anti-[NiNO{P(OMe)3][1,2-C6H4(PMePh)2}]PF6

Diastereoselectivity and Molecular Recognition in the Self-Assembly of Double-Stranded Dinuclear Metal Complexes of the Type [M₂{(R,S)-tetraphos}₂](PF₆)₂ (M = Ag and Au)