Protonic–Hydridic Bifunctionality: The Protonic (2‐Aminoethyl)dimethylphosphane Ligand in Nitrosyl Tungsten Hydride Complexes

Abstract

The chemistry of nitrosyl tungsten hydrides bearing the (2‐aminoethyl)dimethylphosphane ligand (edmp) with an acidic NH functionality was studied. Such complexes were targeted by applying the reaction of WCl3(NO)(CH3CN)2 with edmp, which gave [WCl2(NO)(η2‐edmp)2][Cl] (1a) and [WCl2(NO)(η2‐edmp)2][BPh4] (1b). Complex 1b was treated with Zn to produce [W(H)(Cl)(NO)(η2‐edmp)2][BPh4] (2b). Subsequent attempts with the use of WCl(NO)[P(OMe)3]4 and edmp as starting materials produced {W(NO)(η2‐edmp)2[P(OMe)3]}[Cl] (3a) at 85 °C and [W(H)(Cl)(NO)(η2‐edmp)2][Cl] (2a) at 120 °C. Substitution of the P(OMe)3 ligand in {W(η2‐edmp)2(NO)[P(OMe)3]}[BPh4] (3b) with CO afforded [W(CO)(η2‐edmp)2(NO)][BPh4] (4b). Complex 4b was treated withNaHBEt3, resulting in a dihydride product [W(CO)trans‐(η1‐edmp)2(H)2(NO)]Na (4c). The chlorido complexes containing one η2‐edmp ligand WCl(NO)(η2‐edmp)(PMe3)2 (5a), WCl(NO)(η2‐edmp)(CO)(PMe3) (6a), WCl(NO)(η2‐edmp)[P(OMe)3]2 (5b), and WCl(NO)(CO)(η2‐edmp)[P(OMe)3] (6b) were prepared and treated with NaHBEt3 to obtain the corresponding hydride species WH(NO)(η2‐edmp)[P(OMe)3]2 (8b), WH(NO)(CO)(η2‐edmp)(PMe3) (7a), and WH(NO)(CO)(η2‐edmp)[P(OMe)3] (7b). The initially formed WH(NO)(η2‐edmp)(PMe3)2 (8a) was spontaneously transformed into the amide complex W(NO)(CO)(NHCH2CH2PMe2)(PMe3) (11a) with loss of H2. The anionic dihydride products [W(H)2(η1‐edmp)(NO)L2]Na [L = PMe3 (9a) and L = PMe3 (9b)] were produced from 7a and 7b by the reaction with NaHBEt3. Hydride 8b turned out to be the most stable hydride complex in the given series. NMR spectroscopic experiments and deuterium labeling showed that 8b coexists in equilibrium with corresponding dihydrogen amide complex 10b. The structures of compounds 1a, 2b, 3a, 4b, 5b, 6a, and 6b were studied by single‐crystal X‐ray diffraction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Bifunctional W/NH Cuboidal Aminophosphino W3S4 Cluster Hydrides: The Puzzling Behaviour behind the Hydridic‐Protonic Interplay

“…In contrast to 1 + , these mononuclear compounds are very unstable and the complexity of the reaction mixture made the assignment of the 1 H NMR signals of the edmp NH 2 and CH 2 protons difficult. [12] In spite of this, they were able to assign the hydrido resonances, which fall within the 2.4 and 4.3 ppm range. In the case of the most stable WH(NO)[P(OMe) 3 ] 2 (edmp) complex, NMR spectroscopic experiments and deuterium labelling suggest that this species coexists in equilibrium with the corresponding dihydrogen amide W(H 2 )(NO)[P(OMe) 3 ] 2 (edmp-H) complex.…”