37834-17-6Relevant academic research and scientific papers
Synthesis, characterization and the thermal isomerization mechanism of a series of trans-tetracarbonyl-bis(phosphinite)molybdenum(0) complexes and an evaluation of their potential to form heterobimetallic compounds
Martin, Justin R.,Hastings, Samantha D.,Freeman, Jason L.,Gray, Gary M.
, p. 695 - 702 (2014/03/21)
The reactions of coordinated phosphorus-donor ligands have previously been used to prepare bimetallic trans-[cis-Mo(CO)4(PPh 2NHCH2CH2NCH(o-C6H4)O) 2]M (M = Ni(II), Cu(II)) complexes. Similar bimetallic complexes containing trans-tetracarbonyl-bis(phosphinite)molybdenum(0) centers could be even more interesting because they could serve as molecular gyroscopes. In an attempt to prepare such complexes, the three intermediate compounds trans-Mo(CO)4(PPh2Cl)2 (1), trans-Mo(CO) 4(PPh2NHCH2CH2NH2) 2 (2), and trans-Mo(CO)4(PPh2NHCH 2CH2NCH(o-C6H4)OH)2 (3) were successfully synthesized and fully characterized by multinuclear NMR spectroscopy, elemental analysis and X-ray crystallography. However, the reaction of 3 with Ni(OAc)2(H2O)4 yielded a mixture of crude products with the previously reported trans-[cis-Mo(CO) 4(PPh2NHCH2CH2NCH(o-C6H 4)O)2]Ni being the only product successfully isolated. The cis product was formed due to facile transecis isomerization during the coordination of the Ni(II) to 3. To gain more insight into such isomerizations, the transecis isomerizations of 2 and 3 have been followed by 31P{1H} NMR spectroscopy. The reactions follow reversible first order kinetics and appear to display intramolecular mechanisms due to the lack of carbonyl substitutions of the phosphinamidite ligands when the isomerizations are performed under CO atmospheres. Eyring analyses performed on the two complexes show that they have nearly identical activation energies (2: ΔH = 10 ± 2 kJ mol-1, ΔS = 39±5 J mol -1 K-1; 3: ΔH = 11±2 kJ mol-1, ΔS = 41 ± 7 J mol-1 K-1).
Exploring the coordination chemistry and reactivity of dialkylamino- and bis(dialkylamino)-phosphines in the coordination sphere of metals
Dyer, Philip W.,Fawcett, John,Hanton, Martin J.,Kemmitt, Raymond D.W.,Padda, Ranbir,Singh, Narendra
, p. 104 - 113 (2007/10/03)
The coordination chemistry of a range of dialkylamino- and bis(dialkylamino)-phosphines, RxP(NR′2) 3-x (x = 1 or 2; R = Cl, Me, Ph, C6F5; R′ = Et, Pri), 1-7, has been studied and the resulting Group 6 tetracarbonyl and platinum dichloride bis(phosphine) complexes fully characterised. Subsequently, the reactivity of the P-N bonds of the metal-bound phosphines was probed. Treatment of R″OH (R″ = Me, Et, allyl) solutions of the bis(dialkylaminodiphenylphosphine) complexes with anhydrous HCl gas led to substitution of NR′2 by OR″; the resulting P-alkoxy complexes were isolated in excellent yields. Acidification of ethylene glycol solutions of the aminophosphine complexes afforded the corresponding bis(chlorodiphenylphosphine) derivatives. Following reaction of trans-[W(CO)4(P{NEt2}Ph2)2] with either aqueous HCl or H2SO4, trans-[W(CO) 4(P{OH}Ph2)2] could be isolated as its dichloromethane solvate in excellent yield (81%). Reactions of the bis(bis{dialkylamino} phenylphosphine) complexes under identical conditions yielded a range of unidentified products. Reactions of ligands 1-7 with [{RhCl(CO)2}2] and elemental selenium have been undertaken and the products used to assess the phosphines' donor capabilities. Depending on the substituents at phosphorus, either trans-diphosphine or cis-dicarbonyl complexes result from reaction with [{RhCl(CO)2} 2]. The sterically demanding phosphine P(NPr2 i)2Ph (5) proved unreactive towards complexation with metals, although its selenide could be prepared and isolated. In order to probe the observed lack of oxidation or complexation the molecular structure P(NPr2i)2(C6F5) has been determined by X-ray crystallography. The Royal Society of Chemistry 2003.
