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Children learn through play, and they learn more than adults might expect. Science experiments are a great way to spark their curiosity, get their minds active, and encourage them to do something that doesn’t involve a screen. 1038-95-5, C21H21P. A document type is Article, introducing its new discovery., category: chiral-phosphine-ligands
Treatment of (dppm = Ph2PCH2PPh2) with gave the bimetallic <(OC)3Fe(mu-dppm)(mu-CO0pt(PPh3)> (1) in 75percent isolated yield.Complex (1) was also prepared by the sodium tetrahydroborate reduction of <(OC)3Fe(mu-dppm)(mu-CO)PtCl2> in the presence of PPh3.Its structure was established by X-ray crystallography: the crystals are triclinic, space group P1, with a = 1177.3(2), b = 1198.4(1), c = 1776.5(1) pm, alpha = 103.34(1), beta = 107.81(1), gamma = 91.76(1) deg, and Z = 2; final R factor 0.0257 for 5422 observed reflections.The structure shows that one of the carbonyl ligands is almost symmetrically bridging the Fe-Pt bond.Protonation of complex (1) with HBF4.OEt2 gave the hydride <(OC)4Fe(mu-dppm)PtH(PPh3)> (4), 1H n.m.r. studies of which indicated the hydride ligand to be terminal on platinum.Ethyne reacted with (1) at 20 deg C to give the complex <(OC)4Fe(mu-dppm)Pt(PPh3)> (5), the structure of which was established by X-ray crystallography: the crystals are orthorhombic, space group Pbca, with a = 1898.9(4), b = 1828.3(3), c = 2414.4(5) pm, and Z = 8; r 0.0381 for 4163 observed reflections.The molecule contains a dimetallacyclopentenone ring in which the ethylenic bond is epsilon2-bound to iron, so that the C(O)C2H2 moiety is ?-co-ordinated to platinum and epsilon3-co-ordinated to iron.Unsymmetrical alkynes (MeC=CH, PhCCH, 4-MeC6H4CCH, MeNHCH2CCH, HOMe2CCCH, and MeCO2CCH) also reacted with complex (1), at 80 deg C, to give complexes of type <(OC)2Fe(mu-dppm)Pt(PPh3)>.At 20 deg C, MeCCH and 4-MeC6H4CCH reacted with (1) to give isolable complexes of type <(OC)2Fe(mu-dppm)-Pt(PPh3)> which isomerised in solution, at rates dependent on the steric bulk of R, to complexes of type <(OC)2Fe(mu-dppm)Pt(PPh3)>.The mechanism of the alkyne-insertion reactions appears to involve an intermediate containing a monodentate dppm ligand co-ordinated to iron, formed by opening of the five-membered FePCPPt ring in (1).Protonation of the alkyne complexes breaks the alkyne-CO link to give mu-vinyl cations of type <(OC)3Fe(mu-dppm)-(mu-CR=CH2)Pt(PPH3)>+ (R = H, Me, or C6H4Me-4).The structure of <(OC)3Fe(mu-dppm)-(mu-CMe=CH2)Pt(PPh3)> (16) has also been established by X-ray crystallography: the crystals are monoclinic, space group Cc, with a = 2321.3(3), b = 1091.2(2), c = 1962.6(2) pm, beta = 98.48(1) deg, and Z = 4, R 0.0460 for 3615 observed reflections.The structure shows that the mu-CMe=CH2 moiety is ?-co-ordinated to platinum and epsilon2-co-ordinated to iron.Treatment of complex (1) with MeO2CCCCO2Me displaced the PPh3 ligand to give <(OC)4Fe(mu-dppm)-Pt(MeO2CCCCO2Me)> (19).The complex <(OC)3Fe(mu-dppm)(mu-SO2)Pt(PPh3)> (20) was formed in high yield when SO2 was bubbled through a dichloromethane solution of (1).In addition, analogues of many of the above complexes have been prepared with (Ph2P)2C=CH2.
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Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate