171625-87-9Relevant academic research and scientific papers
Li/X phosphinidenoid pentacarbonylmetal complexes: A combined experimental and theoretical study on structures and spectroscopic properties
Streubel, Rainer,Oezbolat-Schoen, Aysel,Von Frantzius, Gerd,Lee, Holly,Schnakenburg, Gregor,Gudat, Dietrich
, p. 3313 - 3325 (2013/04/24)
The synthesis of P-F phosphane metal complexes [(CO)5M{RP(H)F}] 2a-c (R = CH(SiMe3)2; a: M = W; b: M = Mo; c: M = Cr) is described using AgBF4 for a Cl/F exchange in P-Cl precursor complexes [(CO)5M{RP(H)Cl}] 3a-c; thermal reaction of 2H-azaphosphirene metal complexes [(CO)5M{RP(C(Ph)N}] 1a-c with [Et3NH]X led to complexes 3a-c, 4, and 5 (M = W; a-c: X = Cl; 4: X = Br; 5: X = I). Complexes 2a-c, 3a-c, 4, and 5 were deprotonated using lithium diisopropylamide in the presence of 12-crown-4 thus yielding Li/X phosphinidenoid metal complexes [Li(12-crown-4)(Et2O)n][(CO)5M(RPX)] 6a-c, 7a-c, 8, and 9 (6a-c: M = W, Mo, Cr; X = F; 7a-c: M = W, Mo, Cr; X = Cl; 8: M = W; X = Br; 9: M = W; X = I). This first comprehensive study on the synthesis of the title compounds reveals metal and halogen dependencies of NMR parameters as well as thermal stabilities of 6a, 7a, 8, and 9 in solution (F > Cl > Br > I). DOSY NMR experiments on the Li/F phosphinidenoid metal complexes (6a-c; M = W, Mo, Cr) rule out that the cation and anion fragments are part of a persistent molecular complex or tight ion pair (in solution). The X-ray structure of 6a reveals a salt-like structure of [Li(12-crown-4)Et 2O][(CO)5W{P(CH(SiMe3)2)F}] with long P-F and P-W bond distances compared to 2a. Density functional theory (DFT) calculations provide additional insight into structures and energetics of cation-free halophosphanido chromium and tungsten complexes and four contact ion pairs of Li/X phosphinidenoid model complexes [Li(12-crown-4)][(CO) 5M{P(R)X}] (A-D) that represent principal coordination modes. The significant increase of the compliance constant of the P-F bond in the anionic complex [(CO)5W{P(Me)F}] (10a) revealed that a formal lone pair at phosphorus weakens the P-F bond. This effect is further enhanced by coordination of lithium and/or the Li(12-crown-4) countercation (to 10a) as in type A-D complexes. DFT calculated phosphorus NMR chemical shifts allow for a consistent interpretation of NMR properties and provide a preliminary explanation for the abnormal NMR shift of P-Cl derivatives 7a-c. Furthermore, calculated compliance constants reveal the degree of P-F bond weakening in Li/F phosphinidenoid complexes, and it was found that a more negative phosphorus-fluorine coupling constant is associated with a larger relaxed force constant.
Stereochemically defined metal carbene complexes as chemical probes for studies of the ring formation of 2H-azaphosphirene complexes
Streubel, Rainer,Priemer, Siegfried,Jeske, J?rg,Jones, Peter G.
, p. 423 - 434 (2007/10/03)
Strong evidence for a strictly intramolecular rearrangement process leading to 2H-azaphosphirene complex 4 was obtained by reactions of {[amino(phenyl)carbene]pentacarbonyltungsten(0)} (1) with [bis(trimethylsilyl)methylene]chlorophosphane (2) and triethylamine under CO atmosphere; the byproducts, dinuclear carbene complexes 3a,b, were obtained and characterized as E,E- and E,Z-isomers. Reaction of a 5:2 mixture of complexes 3a,b with triethylamine in dichloromethane afforded 2H-azaphosphirene complex 4 and another product 5, which could not be isolated, but showed 31P-NMR characteristics of a σ4λ5-phosphorus center possessing a P-H function. {cis-[ethoxy/amino(aryl)carbene](triorganylphosphane)chromium(0)} and -tungsten(0) complexes 6a,b, 7a,b and 11, 12 were synthesized, 6a and 7b additionally characterized by X-ray crystallography, and reacted also with methylene(chloro)phosphane 2 in the presence of triethylamine, thus yielding cis-2H-azaphosphirene triorganylphosphane complexes 8a,b and 13a,b, which were unambiguously confirmed by NMR spectroscopy. The latter reactions proceeded with cis-stereospecificity. Significant chiral induction was not observed in the reaction leading to 13a,b, and racemization occured, most probably, at the phosphorus of the 2H-azaphosphirene complex. These results provide strong evidence for non-participation of the metal atom center in the ring-closure process giving the three-membered 2H-azaphosphirene ring system.
Synthesis of the first stable Fischer-type carbene metal complex with a C-O-P structural motive of the carbene ligand
Streubel, Rainer,Hobbold, Markus,Priemer, Siegfried
, p. 56 - 59 (2007/10/03)
Fischer-type (phenyl)carbene pentacarbonyltungsten complexes, which have an organo phosphorus moiety bonded to oxygen (5, 8) or to nitrogen (10a,b), are synthesized by reaction of the O-Li and N-Li precursor carbene complexes with either bis(diisopropylamino)chlorophosphane (5) and/or [bis(trimethylsilyl)methylene]chlorophosphane (8, 10a,b) via lithiumchloride elimination; whereas the bulky substituted complex 5 decomposed in solution under formation of bis(diisopropylamino)-chlorophosphaneoxide via an unknown reaction pathway, complex 8 was stable at ambient temperature; complexes 10a,b slowly rearranged in solution to the 2H-azaphosphirene complex 11; the complexes 8 and 10a,b were unambiguously confirmed by NMR spectroscopy.
Synthesis and spectroscopic data of para-substituted (3-phenyl-2H-azaphosphirene)tungsten complexes
Streubel, Rainer,Ostrowski, Annette,Priemer, Siegfried,Rohde, Udo,Jeske, Joerg,Jones, Peter G.
, p. 257 - 261 (2007/10/03)
High-yield synthesis of para-substituted pentacarbonyl(3-phenyl-2H-azaphosphirene)tungsten complexes is reported, using a multi-step rearrangement reaction. Spectroscopic and mass-spectrometric data of these heterocyclic complexes are discussed; the 31P-NMR-chemical shifts clearly reflect the electronic influence of the para-phenyl substituents and the correlation with Hammett σp-constants is almost linear.
