190439-87-3Relevant academic research and scientific papers
Highly Active and Iso-Selective Catalysts for the Ring-Opening Polymerization of Cyclic Esters using Group 2 Metal Initiators
Bhattacharjee, Jayeeta,Harinath, Adimulam,Nayek, Hari Pada,Sarkar, Alok,Panda, Tarun K.
, p. 9319 - 9331 (2017/07/17)
A series of alkali and alkaline earth (Ae) metal complexes bearing 1,2-phenylene(bis-diphenylphosphinothioic/selenoic amine) [{Ph2P(E)NH}2C6H4] (E=S (1-H2); Se (2-H2) ligands are reported. Alkali metal complexes [{Ph2P(S)N}2C6H4]Na(THF)4 (3 a) [{Ph2P(Se)N}2C6H4]Na(THF)4 (3 b), and [{Ph2P(Se)N}2C6H4]K(THF)5 (4 b) were obtained in good yield by treating protic ligands 1-H2 or 2-H2 with metal hexamethyldisilazides [MN(SiMe3)2] (M=Na or K) at ambient temperature. The Ae metal complexes formulated as [{Ph2P(E)N}2C6H4]M(THF)3 [E=S, M=Ca (5 a), Sr (6 a), Ba (7 a); E=Se, M=Ca (5 b), Sr (6 b), Ba (7 b)] can be synthesized by using two routes. The molecular structures of the free ligand 1-H2 and metal complexes 5 a,b–7 a,b in their solid states were established. Complexes 3 a and 3 b are isostructural; however, in complex 4 b, an attachment different from ligand 2 was observed. The complexes 5 a,b–7 a,b are isostructural and each metal ion exhibits a distorted pentagonal bipyramidal geometry around it. All Ae metal complexes 5 a,b–7 a,b were tested for the ring-opening polymerization (ROP) of racemic lactide (rac-LA) and ?-caprolactone (?-CL) at room temperature. Calcium complexes 5 a and 5 b show excellent iso-selectivity, with Pi values of 0.78–0.87 at 298 K and with a high degree of polymerization control, whereas the corresponding strontium complexes 6 a and 6 b exhibit moderate iso-selectivity, and barium complexes 7 a and 7 b yield only atactic polylactides (PLAs). In all cases, the catalyst initiates the ROP catalytic cycle in the absence of any external initiator. Kinetic studies of the polymerization reactions indicate the relative order of polymerization rate increases with increase in the size of the metal ion: Ba>Sr>Ca.
Chelating bis(thiophosphinic amidate)s as versatile supporting ligands for the group 3 metals. An application to the synthesis of highly active catalysts for intramolecular alkene hydroamination
Kim, Young Kwan,Livinghouse, Tom,Horino, Yoshikazu
, p. 9560 - 9561 (2007/10/03)
Bis(thiophosphinic amidate) complexes (i.e., 1) of representative group 3 and lanthanide metals have been quantiatively prepared in situ from the corresponding thiophosphinic amides and Ln[N(TMS)2]3. These unusual pentacoordinate complexes exhibit very high activity as catalysts for intramolecular alkene hydroamination. Copyright
Synthesis, co-ordination chemistry and crystallographic studies of some bis(aminophosphines)
Ly, Tuan Q.
, p. 1611 - 1616 (2007/10/03)
l,2-Bis(diphenylphosphinoamino)benzene 1 and 3,4-bis(diphenylphosphinoamiho)toluene 2 have been prepared; 1 is oxidised by sulfur or selenium to C6H4(NHPPh2S)2-l,2 3 and C6H4(NHPPh2Se)2-l,2 4 and by sulfur and selenium to C6H4(NHPPh2S)(NHPPh2Se)-l,2 5. The napthalene compounds C)0H6(NHPPh2S)2-l,8 6, CIOH6(NHPPh2Se)2-l,8 7, C10H6(NHPPh2S)(NHPPh2Se)-l,8 8 and the ethane compound C2H4(NHPPh2S)2-l,2 9 have also been prepared. The co-ordination of 2 to Mo°, Pd, Pt and Au1, i.e. in cw-[Mo(CO)4L], cw-[MC!2L] (M = Pd or Pt) and [(AuCl)2L] [L = MeC6H3(NHPPh2)2-3,4] is also described. The crystals structures of representative examples have been determined.
