435269-17-3Relevant academic research and scientific papers
Unrealized concepts of masked alkylidenes in (PNP)FeXY systems and alternative approaches to LnXmFe(IV)=CHR
Cundari, Thomas R.,George, Gregory M.,MacMillan, Samantha N.,Wolczanski, Peter T.
, (2020)
Treatment of PNP ligands with iron(II) halides yielded pseudo tetrahedral {(Ph2PCH2)2NR}FeX2 (R″ = tBu, 1a-X; Me, 1b-X) and {(iBu2PCH2)2NR″}FeX2 (R″ = tBu, 2a-X; Me, 2b-X) complexes, which could be mono- and dialkylated to afford various {(Ph2PCH2)2NR″}FeCl(R) (R″ = tBu, 3a-R; Me, 3b-R), {(iBu2PCH2)2NR″}FeCl(R) (R″ = tBu, 4a-R; Me, 4b-R), {(Ph2PCH2)2NtBu}Fe(neoPe)2 (5a-neoPe) and {(iBu2PCH2)2NtBu}Fe(1-nor)2 (6a-nor). All of the complexes were high spin (S = 2), and structural studies of {(Ph2PCH2)2NMe}FeCl2 (1b-Cl), {(iBu2PCH2)2NtBu}FeCl2 (2a-Cl), and {(iBu2PCH2)2NtBu}FeCl(1-nor) (4a-nor), revealed chair conformations for the PNP ligands, which were calculated to have modest barriers to boat configurations via twist-boats as calculational minima. Attempts to convert these complexes to zwitterionic NCRR′Fe-containing species as “masked alkylidenes” failed to materialize. Alternative approaches involving structurally characterized diamagnetic {(iBu2PCH2)2NtBu}(CO)2FeCl(COneoPe) (8), the carbonylation product of 4a-neoPe, and low-valent {(Ph2PCH2CH2)2NtBu}Fe((H2C=CHSiMe2)2O) (9) also failed. An analysis of orbital energies and overlap is given for alkylidenes. Covalence is identified as a crucial feature necessary for the alkylidene to metalacyclobutane transformation in metathesis.
Synthesis of cobalt(II) and iron(II) complexes with the ligand bis(2-diphenylphosphinoethyl)methylamine and their catalytic action on ethylene oligomerization. X-ray crystal structure of
Wang, Mei,Yu, Xiaomin,Shi, Zhan,Qian, Mingxing,Jin, Kun,Chen, Jiesheng,He, Ren
, p. 127 - 133 (2007/10/03)
Complexes [MCl2{CH3N(CH2CH2PPh2)2}] (1, M = Co; 2, Fe) were prepared by a modified procedure. The X-ray structural determination of 1 reveals that the cobalt(II) complex is four-coordinate with a distorted tetrahedral coordination geometry. The tertiary amine CH3N(CH2CH2PPh2)2 acts as a bidentate ligand through two phosphorus atoms. The Co-P distances of 2.3666(14) and 2.3731(15) ? found in 1 are significantly longer than general Co-P bond lengths. The incoordinate N atom of the ligand locates at the apical position trans to one of the chlorides. The catalytic properties of 1 and 2 in combination with ethylaluminoxane (EAO) as cocatalyst for ethylene oligomerization were studied. The activities of 89.4 kg oligomers mol-1 Co h-1 for 1 and 81.2 kg oligomers mol -1 Fe h -1 for 2 (100 equivalents of EAO, 180 °C and 1.8 MPa ethylene) were observed with high selectivity to linear C4-10 olefins.
