155850-41-2Relevant academic research and scientific papers
Bonding and activation of N2 in Mo(0) complexes supported by hybrid tripod ligands with mixed dialkylphosphine/diarylphosphine donor groups: Interplay of steric and electronic factors
Soencksen, Ludger,Gradert, Christian,Krahmer, Jan,Naether, Christian,Tuczek, Felix
, p. 6576 - 6589 (2013/07/11)
Molybdenum dinitrogen complexes are presented which are supported by novel hybrid tripod ligands of the type Me-C(CH2PPh2) 2(CH2PiPr2) (trpd-1) and H-C(CH 2PPh2)(CH2PiPr2) 2 (trpd-2) having mixed dialkylphosphine/diarylphosphine donor groups. Reaction of the ligand trpd-1 with [MoI3(thf)3] followed by sodium amalgam reduction in the presence of the dppm gives the dinitrogen complex [Mo(N2)(trpd-1)(dmpm)] where trpd-1 is coordinated in a κ3 fashion. The complex exhibits a moderate activation of N2 which enables its protonation under retention of the pentaphosphine ligation. Replacement of dmpm by the sterically more demanding coligand dppm is found to hamper coordination of N2 and leads to [Mo(trpd-1)(dppm)], the first structurally characterized five-coordinate Mo(0) complex with a phosphine-only ligand sphere. Employing the ligand trpd-2 along with the diphosphines dmpm and dppm in an analogous synthetic route results in a mixture of the bis(dinitrogen) complexes trans-[Mo(N2) 2(κ2-trpd-2)(diphosphine)] and trans-[Mo(N 2)2(iso-κ2-trpd-2)(diphosphine)] where the tripod ligand trpd-2 coordinates with two phosphine arms and one phosphine group (PPh2 or PiPr2, respectively) is free. Similar results are obtained with the pure alkyl-and arylphosphine tripod ligands H-C(CH2PiPr2)3 (trpd-3) and H-C(CH2PPh2)3 (tdppmm), leading to trans-[Mo(N2)2(κ2-trpd-3)(diphos)] and trans-[Mo(N2)2(κ2-tdppmm)(dmpm)], respectively. The electronic and steric reasons for the experimental findings are considered, and the implications of the results for the area of synthetic nitrogen fixation with molybdenum phosphine systems are discussed.
Modulating the propeller-like shape of a tripodal C(CH2PPh2)3 fragment by the size of the substituent at the pivotal carbon atom in macrobicyclic tri-λ5-phosphazenes
Alajarín, Mateo,López-Leonardo, Carmen,Berná, José
, p. 4450 - 4458 (2008/02/03)
The chiral macrobicyclic tri-λ5-phosphazenes formed by tripod-tripod coupling of tris(3-azidobenzyl)amines and 1,1,1-tris[(diphenylphosphino)methyl]methanes present helical topologies as a result of combining two propeller-shaped tripodal fragm
Center-to-propeller and propeller-to-propeller stereocontrol in a series of macrobicyclic tri-λ5-phosphazenes
Alajarín, Mateo,López-Leonardo, Carmen,Berná, José,Sánchez-Andrada, Pilar
, p. 3583 - 3586 (2008/02/02)
Center-to-propeller stereocontrol in a family of macrobicyclic, double-propeller shaped tri-λ5-triphosphazenes remains constant in the upper tribenzylamine fragment as the size of the pivotal group at the lower tris(phosphane) fragment is gradu
Functionalized Tripod Ligands: Synthesis and Coordination of 1,1,1-Trismethane
Janssen, Bernd C.,Asam, Alexander,Huttner, Gottfried,Sernau, Volker,Zsolnai, Laszlo
, p. 501 - 506 (2007/10/02)
The tripod ligand HC(CH2PPh2)3 (4) is easily available from the reaction of 1,3-dichloro-2-(chloromethyl)propane (3) with lithium diphenylphosphide.The ligand 4 itself and two of its coordination compounds, (+)(-) (5*BPh4) and (2+)*2(-) have been characterized by X-ray analyses.Coordination of 4 leads to an opening of the CH2-CH-CH2 bond angles (114 deg in 7*(BF4)2 and 5*BPh4 versus 111 deg in 4).This change in structure is reflected by the unusual low field shift of the methine hydrogen of 7*(BF4)2 (δ=3.90) in comparison with the corresponding signal of the free ligand 4 (δ=1.53). - Key Words: Tripod ligand synthesis / Tripod iron trisacetonitrile complexes / Tripod cobalt acetate complexes
