Molybdenum Bis(Dinitrogen) Complexes Supported by NP₃ Ligands containing Propylene Linkages: Symmetry Breaking and Geometrical Isomerism

Abstract

The syntheses of two new NP 3 ligands containing propylene linkages, prNP 3 (1) = N(CH 2 CH 2 CH 2 PPh 2 ) 3 and prPNetP 2 (2) = (Ph 2 PCH 2 CH 2 CH 2 )N(CH 2 CH 2 PPh 2 ) 2 are reported. Using these ligands, bis(dinitrogen) complexes of molybdenum are synthesized and characterized by IR and NMR spectroscopy. The new systems are com-83 pared with the literature-known complex [Mo(N 2 ) 2 (NP 3 )] (3) supported by the ligand NP 3 [NP 3 = N(CH 2 CH 2 PPh 2 ) 3 ], which only contains ethylene linkages. Application of the new ligand reduces the symmetry of the complex and leads to the occurrence of different isomers.

Molybdenum dinitrogen complexes facially coordinated by linear tridentate PEP ligands (E = N or P): impact of the central E donor in trans-position to N2

“…[18][19][20][21][22] Moreover, we studied molybdenum (dinitrogen) complexes supported by tetradentate NP 3 ligands in which the trans position of one dinitrogen ligand is occupied by a N atom. 23 An alternative strategy to the described approaches is the synthesis of dinitrogen complexes supported by tridentate PEP ligands in which the trans position of coordinated N 2 is occupied by the central donor atom E (E = P or N) of the ligand and the two remaining equatorial positions are occupied by a diphosphine coligand. The prototypical example of a molybdenum dinitrogen complex having this ligand environment is the complex [Mo(N 2 )(dpepp)(dmpm)] (1) prepared by George et al…”

“…Recently we have investigated this problem based on molybdenum dinitrogen complexes supported by tetradentate NP 3 ligands. 23 Elongation of the C 2 bridges of the parent NP 3 ligand by one CH 2 group caused a breaking of the mirror symmetry of the complex cis-[Mo(N 2 ) 2 (prNP 3 )]. For the complex cis-[Mo(N 2 ) 2 (prPNetP 2 )] supported by an asymmetrically substituted NP 3 ligand with one C 3 and two C 2 bridges three isomers were found, each lacking a mirror plane.…”

Coordination Modes of Aminodiphosphane Ligands to the Cuboidal Mo3S4 Cluster Unit

“…To our knowledge, coordination of the PNP ligand to molybdenum always occurs in a tridentate mode while dangling phosphino groups are found in mononuclear complexes functionalized with NP3-type tripodal aminophosphane ligands. [35][36][37][38] The most remarkable differences in the bond distances between the metal and the atoms (P, N and Cl) of the outer ligands refer to the Mo-N bond lengths that are ca. 0.07 Å longer in [Mo-1] + than those observed for previously reported [Mo3S4Cl3(aminophosphane)3] + complexes.…”

A One-Step Preparation of Tetradentate Ligands with Nitrogen and Phosphorus Donors by Reductive Amination and Representative Iron Complexes

“…31 Increased flexibility can be achieved by lengthening the ethylene spacers to propylene in order to accommodate larger atoms like Mo(0). 32 Unsymmetrical tetradentate ligands have also been reported where one phosphorus donor is substituted for an additional nitrogen donor, resulting in an open-chain P 2 N 2 framework if the nitrogen donors are geometrically equivalent, or a P 2 NN′ framework if they are not. 33 Chiral, open-chain P 2 N 2 tetradentate ligands have been shown to be very useful ligands for the asymmetric transfer hydrogenation of polar bonds.…”

“…An unsymmetrical NP 2 P ligand with two chains linked by methylene spacers and one chain linked with an ethylene spacer has been reported with ruthenium for the hydrogenation of biobased carboxylic acids . Increased flexibility can be achieved by lengthening the ethylene spacers to propylene in order to accommodate larger atoms like Mo(0) . Unsymmetrical tetradentate ligands have also been reported where one phosphorus donor is substituted for an additional nitrogen donor, resulting in an open-chain P 2 N 2 framework if the nitrogen donors are geometrically equivalent, or a P 2 NN′ framework if they are not .…”