- Syntheses and structures of square planar diplatinum butadiynediyl complexes with two different monophosphine ligands on each terminus; probing the feasibility of a new type of inorganic atropisomerism
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Reactions of trans-(C6F5)(p-tol3P)2Pt(Cl) (PtCl) and R2PhP (1.0 equiv; R = a/Me, b/p-t-BuC6H4, c/p-MeOC6H4, d/n-Pr; CH2Cl2/rt (a) or toluene/reflux (b-d)) give mainly trans-(C6F5)(R2PhP)(p-tol3P)Pt(Cl) (Pt′Cl-a-d, 89-29%) and some disubstitution products trans-(C6F5)(R2PhP)2Pt(Cl) (Pt″Cl-a-d, 4–13%). No substitution occurs with t-Bu2PhP. However, (cod)(C6F5)Pt(Cl) and t-Bu2PhP (2.7 equiv; toluene/reflux) react to give trans-(C6F5)(t-Bu2PhP)2Pt(Cl) (Pt″Cl-e, 64%), which upon treatment with p-tol3P (1.0 equiv, toluene/reflux) yields trans-(C6F5)(t-Bu2PhP)(p-tol3P)Pt(Cl) (Pt′Cl-e, 91%). Additions of excess butadiyne to Pt′Cl-a-d (CH2Cl2, cat. CuI, HNEt2) afford the butadiynyl complexes trans-(C6F5)(R2PhP)(p-tol3P)Pt(C≡C)2H (Pt′C4H-a-d, 36–77%), but Pt′Cl-e does not similarly react. Cross couplings of Pt′Cl-a-c and Pt′C4H-a-c (cat. CuI, HNEt2) give mixtures of diplatinum butadiynyl complexes in which the two unlike phosphine ligands scramble over all four positions (PtC4Pt, PtC4Pt′-a-c, PtC4Pt″-a-c, Pt′C4Pt′-a-c, Pt′C4Pt″-a-c, Pt″C4Pt″-b; TLC separable, 27-2% each). A modified coupling recipe is tested with Pt′Cl-b,d and Pt′C4H-b,d (t-BuOK, KPF6, cat. CuCl), and gives Pt′C4Pt′-b,d (21–76%) with only traces of scrambling. Crystal structures of Pt″Cl-e, Pt′C4H-a, Pt′C4Pt′-a-d, and PtC4Pt″-b are determined, and the endgroup/endgroup interactions analyzed. Low temperature NMR spectra do not reveal any dynamic processes.
- Dey, Sandip,Zhang, Tianyi,Bhuvanesh, Nattamai,Gladysz, John A.
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p. 237 - 255
(2017/10/05)
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- Cyclohexyneplatinum(0) Complexes Containing Di-t-butylphenylphosphine, t-Butyldiphenylphosphine or Trimethylphosphine
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Cyclohexyneplatinum(0) complexes Pt(C6H8)L2 (L = PBut2Ph (4), PButPh2 (5)> analogous to the known complex (3) (L = PPh3) have been prepared by reaction of the two-coordinate complexes PtL2 with 1,2-dibromocyclohexene and 1percent sodium amalgam.The corresponding tricyclohexylphosphine complex is formed by a similar reaction but it could not be isolated in a pure state.Attempts to prepare analogues of (4) and (5) containing cycloheptyne or cyclooctyne were unsuccessful, possibly because the bulky t-butyl groups of the tertiary phosphines hinder coordination of the largerrings.Bulky tertiary phosphines do not displace PPh3 from (3) but trimethylphosphine reacts with (3) to give successively Pt(C6H8)(PMe3)(PPh3) (10) and Pt(C6H8)(PMe3)2 (11), as shown by 31P n.m.r spectroscopy.The tertiary phosphines in these complexes equilibrate rapidly at room temperature in benzene and only (10) can be isolated as a solid from the reaction.Complexes (4) and (5) react with HCl (1 molar proportion) to give η1-cyclohexen-1-yl complexes trans-PtCl(C6H9)L2 t2Ph (6), PButPh2 (7)>.In the absence of air, (4) reacts with methanol at 65 deg C to give the hydrido complex trans-PtH(C6H9)(PBut2Ph)2 (8).In the presence of oxygen from the air, however, the main product is the dioxygen complex Pt(O2)(PBut2Ph)2 (9).This represents an unusual example of complete displacement of cyclohexyne from a platinum(0) complex by a ?-acceptor ligand.
- Bennett, Martin A.,Fick, Hans-Georg,Warnock, Garry F.
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p. 135 - 142
(2007/10/02)
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- Stereodynamics of trans-MCl2 and trans-2M(CO)Cl . Dynamic NMR and X-ray Crystallographic Studies
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Single-crystal X-ray analysis of trans-2MCl2 for which M = Pt(II) or Pd(II) reveals a molecular conformation (CI) in which both phenyl groups are mutually anti.In both cases, the metal atom lies on a crystallographic inversion cente
- DiMeglio, Christine M.,Luck, Linda A.,Rithner, Christopher D.,Rheingold, Arnold L.
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p. 6255 - 6263
(2007/10/02)
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- Preparation, characterization, and some reactions of tri-tert-butylarsine complexes of platinum(II) and palladium(II) chlorides
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As(t-Bu)3 reacts with platinum(II) chlorides to afford either trans-PtCl2[As(t-Bu)3]2 or the dinuclear complex Pt2(μ-Cl)2Cl2[As(t-Bu)3] 2. With palladium(II) chloride, however, only the dinuclear complex Pd2(μ-Cl)2Cl2[As(t-Bu)3] 2 is formed even in the presence of excess As(t-Bu)3. These complexes undergo substitution and/or bridge-cleavage reactions with CO, py, AsPh3, Cl-, or tertiary phosphines.
- Goel, Ram G.,Ogini, William O.,Srivastava, Ramesh C.
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p. 3611 - 3616
(2008/10/08)
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