Stereoselective Synthesis of the First Chatt‐Type Bis(dinitrogen)‐Molybdenum(0) Complex with a Tetraphosphane Ligand

Abstract

The first Chatt‐type Mo0 dinitrogen complex with a tetraphosphane ligand has been prepared and characterized by NMR as well as infrared and Raman spectroscopy. Importantly, the employed reaction route allows the stereospecific synthesis of this complex as trans‐[Mo(N2)2(meso‐prP4)] (prP4 = a tetraphos ligand with a central propylene bridge). The stereoselectivity in the reaction course is induced by the oxido‐iodido‐molybdenum(IV) precursor [Mo(O)I(prP4)]+ which directs both phenyl groups of the bridging P atoms of prP4 into a meso configuration. The paper establishes a general strategy to synthesize mononuclear Mo0 dinitrogen and related molybdenum complexes with multidentate phosphane ligands which has not been possible to date. Moreover, the obtained molybdenum tetraphos N2 complex should exhibit a higher thermodynamic stability in the reactions of the Chatt cycle of synthetic nitrogen fixation than the conventional bis(diphos) complexes, due to the linkage of the two diphosphane units by an alkyl bridge. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Molybdenum Iodides – from Obscurity to Bright Luminescence

“…The iodide complex catalyzes atom transfer radical polymerization of styrene, yielding polymers with narrow molecular weight distribution . [MoOI 2 (PMe 3 ) 3 ] was further converted, by treatment with a tetradentate phosphane ligand, 1,1,4,8,11,11‐hexaphenyl 1,4,8,11‐tetraphosphaundecane (prP 4 ), and NaBPh 4 , into [MoOI(prP 4 )](BPh 4 ), which was then electrolytically reduced at – 2.1 V (vs. Ag electrode) under N 2 in THF to give trans ‐[Mo(N 2 ) 2 (prP 4 )] . [MoOI(dmpe) 2 ]I was also reported …”

The First Molybdenum Oxo‐iodide Cluster – [Mo4OI12]2–

“…The only known molybdenum oxoiodide complexes were those of Mo IV and Mo V , such as [MoOI 2 (PMe 3 ) 3 ], [MoOI 4 (THF)] – , and [Mo 2 O 2 S 2 I 2 (bipy) 2 ] . Their chemistry is not related to that of Mo iodide clusters.…”

One-step synthesis of Mo(0) and W(0) bis(dinitrogen) complexes with the linear tetraphosphine ligand prP4: stereoselective formation of cis-[M(N2)2(rac-prP4)] and trans-[M(N2)2(meso-prP4)]; M = Mo, W

“…Against this background we have prepared the tetradentate phosphine ligand prP 4 (1,1,4,8,11,11-hexaphenyl-1,4,8,11tetraphosphaundecane; 3) and explored its coordination properties in mononuclear complexes. 7,8 The preparation of prP 4 leads to a mixture of the meso and the rac isomer, 3a and 3b, respectively. The meso isomer 3a has the two phenyl rings of the central phosphorus atoms oriented to the same side whereas in the rac isomer 3b the two phenyl rings are located on opposite sides of the ligand.…”

“…7,9,10 In the course of our investigations of the prP 4 ligand 3, the stereospecific synthesis of the molybdenum dinitrogen complex trans-[Mo(N 2 ) 2 (meso-prP 4 )] 2a has been achieved (Scheme 2). 8 The intermediates and the product of the synthesis have been characterized by 31 P{ 1 H}-NMR, vibrational and UV/Vis spectroscopy as well as X-ray structure analysis. As a matter of fact 2a was the first molybdenum bis(dinitrogen) complex with a tetraphosphine ligand.…”