340004-23-1Relevant academic research and scientific papers
Cationic nickel complexes containing bulky phosphine ligands: Catalyst precursors for styrene polymerization
Jimenez-Tenorio, Manuel,Puerta, M. Carmen,Salcedo, Isabel,Valerga, Pedro,Costa, Sandra I.,Silva, Leonel C.,Gomes, Pedro T.
, p. 3139 - 3146 (2008/10/09)
The cationic complexes [Ni(η3-CH2C(R)CH 2)(P)2] IBPh4] (R = Me, H; (P)2 = (PMei-Pr2)2, (PPhiPr 2)2, 1,2-bis(diisopropylphosphino)ethane (dippe)) and [Ni(η-2-MeInd)(P)2] [BPh4] (2-Melnd = 2-methylindenyl; (P)2 = (PMeiPr2)2, (PPh iPr2)2, dippe) have been prepared and characterized. These materials are catalyst precursors for the nonliving polymerization of styrene to polystyrene without the need of a cocatalyst such as methylaluminoxane. The polymerization reactions are carried out in refluxing 1,2-dichloroethane, using a 1:1000 catalyst to styrene ratio, yielding essentially atactic polystyrenes with Mn in the range 14 500-155 000 Da and polydispersities between 1.89 and 9.70. The mass properties of the polymers and the overall yield depend much on the nature of the catalyst precursor.
Structural characterisation of cationic methylallyl, methylindenyl and pentamethylcyclopentadienyl nickel complexes containing the bulky phosphine 1,2-bis(diisopropylphosphino)ethane
Tenorio, Manuel Jimenez,Puerta, M. Carmen,Salcedo, Isabel,Valegra, Pedro
, (2008/10/08)
A novel high-yield, convenient synthetic method for the complex [Ni(COD)2] has been developed based upon the use of dibutylmagnesium as reducing agent. The cationic complexes [Ni(η3CH2C(R)CH2)(dippe)][BPh4] (R = Me la or H 1b; dippe = Pr2iPCH2CH2PPr2i ) were obtained by reaction of [Ni(COD)2] with BrCH2C(R)=CH2 in diethyl ether, followed by treatment with dippe and NaBPh4 in methanol. [Ni(2-MeInd)(dippe)][BPh4] 2 (2-MeInd = 2-methylindenyl) and [Ni(C5Me5)(dippe)][BPh4] 3 were respectively prepared by reaction of either [Ni(2-MeInd)Br(PPh3] or [Ni(C5Me5)Br(PPh3)] with dippe and NaBPh4 in methanol. The crystal structures of 1a, 2 and 3 were determined. All of the compounds show pseudo-square planar two legged piano stool structures. The methylallyl ligand in la shows η3 coordination as expected, whereas in 2 the occurrence of an allyl-ene distortion in the 2-methylindenyl ligand leads to an intermediate η3η5 coordination mode. An intermediate allyl-ene/diene distortion is present in the C5Me5 ligand in 3, although in this case a symmetrical η5 coordination is observed. All compounds were also characterised in solution by NMR spectroscopy.
