7 research outputs found
Mono- and bimetallic amidinate samarium complexes â synthesis, structure, and hydroamination catalysis
Activation of SOâ by [Zn(Cpâ)â] and [(Cpâ)ZnI-ZnI(Cpâ)]
Interesting reactivity was observed in reactions of SO2 with [Zn(Cp*)2] and [(Cp*)ZnIâZnI(Cp*)]. These reactions proceeded with insertion of SO2 into the ZnâC bonds. Spectacularly, the lability of the CâS bond in the O2SCp* ligands led to the thermal decomposition of [Zn(O2SCp*)2(tmeda)] to afford [Zn2(ÎŒ-SO3)(ÎŒ-S2O4)(tmeda)2]
Activation of SO 2 by [Zn(Cp*) 2 ] and [(Cp*)Zn I âZn I (Cp*)]
International audienceInteresting reactivity was observed in reactions of SO2 with [Zn(Cp*)2] and [(Cp*)ZnIâZnI(Cp*)]. These reactions proceeded with insertion of SO2 into the ZnâC bonds. Spectacularly, the lability of the CâS bond in the O2SCp* ligands led to the thermal decomposition of [Zn(O2SCp*)2(tmeda)] to afford [Zn2(ÎŒ-SO3)(ÎŒ-S2O4)(tmeda)2]
Chiral Rare Earth Borohydride Complexes Supported by Amidinate Ligands: Synthesis, Structure, and Catalytic Activity in the Ring-Opening Polymerization of rac-Lactide
International audienceThe monoamidinato bisborohydride rare earth complexes [Ln{(S)-PEBA}(BH4)2(THF)2] (Ln = Sc (1), La (2), Nd (3), Sm (4), Yb (5), Lu (6)) were isolated as crystalline materials upon treatment of potassium N,NâČ-bis((S)-1-phenylethyl)benzamidinate ((S)-KPEBA) with the homoleptic trisborohydrides [Sc(BH4)3(THF)2] and [Ln(BH4)3(THF)3] (Ln = La, Nd, Sm, Yb, Lu), respectively. Compounds 1-6 are unique examples of enantiopure borohydride complexes of the rare earth metals. Different ionic radii of the metal centers were selected to cover the whole range of these elements with respect to the extent of the coordination sphere. All new complexes were thoroughly characterized by 1H, 13C{1H}, 11B, and 15N NMR and IR spectroscopies, also including single-crystal X-ray diffraction structure determination of each compound. The scandium, lanthanum, samarium, and lutetium complexes 1, 2, 4, and 6 were found active in the ring-opening polymerization of rac-lactide under mild operating conditions, providing atactic α,Ï-dihydroxytelechelic poly(lactic acid) (PLA; Mn,SEC up to 18 800 g*mol-1). Most of the polymerizations proceed with a certain degree of control that is directed by molar mass values and relatively narrow dispersities (1.10 < ÄM < 1.34), within a moderate monomer-to-initiator ratio
Chiral Rare Earth Borohydride Complexes Supported by Amidinate Ligands: Synthesis, Structure, and Catalytic Activity in the Ring-Opening Polymerization of <i>rac</i>-Lactide
The monoamidinato bisborohydride rare earth complexes
[LnÂ{(<i>S</i>)-PEBA}Â(BH<sub>4</sub>)<sub>2</sub>(THF)<sub>2</sub>] (Ln = Sc (<b>1</b>), La (<b>2</b>), Nd (<b>3</b>), Sm (<b>4</b>), Yb (<b>5</b>), Lu (<b>6</b>)) were isolated as crystalline materials upon treatment of potassium <i>N</i>,<i>N</i>âČ-bisÂ((<i>S</i>)-1-phenylethyl)Âbenzamidinate
((<i>S</i>)-KPEBA) with the homoleptic trisborohydrides
[ScÂ(BH<sub>4</sub>)<sub>3</sub>(THF)<sub>2</sub>] and [LnÂ(BH<sub>4</sub>)<sub>3</sub>(THF)<sub>3</sub>] (Ln = La, Nd, Sm, Yb, Lu), respectively.
Compounds <b>1</b>â<b>6</b> are unique examples
of enantiopure borohydride complexes of the rare earth metals. Different
ionic radii of the metal centers were selected to cover the whole
range of these elements with respect to the extent of the coordination
sphere. All new complexes were thoroughly characterized by <sup>1</sup>H, <sup>13</sup>CÂ{<sup>1</sup>H}, <sup>11</sup>B, and <sup>15</sup>N NMR and IR spectroscopies, also including single-crystal X-ray
diffraction structure determination of each compound. The scandium,
lanthanum, samarium, and lutetium complexes <b>1</b>, <b>2</b>, <b>4</b>, and <b>6</b> were found active in
the ring-opening polymerization of <i>rac</i>-lactide under
mild operating conditions, providing atactic α,Ï-dihydroxytelechelic
polyÂ(lactic acid) (PLA; <i>M</i><sub>n,SEC</sub> up to 18
800 g·mol<sup>â1</sup>). Most of the polymerizations proceed
with a certain degree of control that is directed by molar mass values
and relatively narrow dispersities (1.10 < <i>Ä</i><sub>M</sub> < 1.34), within a moderate monomer-to-initiator ratio