Wilhelm Kuchen

ZUR KENNTNIS DER ORGANOPHOSPHORVERBINDUNGEN, XXI1 Darstellung von Organobromphosphanen aus RPCl2 und R2 PCl durch Halogenaustausch

Abstract Several methods for the preparation of organobromophosphanes from RPCl2 and R2PCl by halogen exchange are described. In case of aryl compounds optimal results are obtained by equilibration of the chlorophosphanes with PBr3 followed by distillation or crystallization, while gaseous HBr proved to be most efficient for converting the alkyl phosphanes. The isomeric composition of X[sbnd]C6H4PCl2 (X [dbnd] F,Cl,Br,CH3O,(CH3)2N) obtained by Friedel-Crafts reaction is investigated by 31P-NMR. Pure p[sbnd]Cl[sbnd]C6H4PBr2 and p[sbnd]Br[sbnd]C6H4PBr2 can be isolated from the isomeric mixture by crystallization. Verschiedene Methoden zur Darstellung von Organobromphosphanen aus RPCl2 und R2PCl durch Halogenaustausch werden beschrieben. Im Falle der Arylverbindungen liefert die Aquilibrierung der Chlorphosphane mit PBr3 bei anschliesender Destination oder Kristallisation die besten Ergebnisse, wahrend die Umwandlung der Alkylphosphane zweckmasigerweise mit Bromwasserstoffgas erfolgt. Die isomere Zusammenset...

Synthesis, properties and structure of bis(dialkyldithiophosphinato)manganese(II) complexes

Abstract Reaction of Mn 2 (CO) 10 or powdered manganese with bis(diorganothiophosphoryl)disulfanes, R 2 P(S)- S 2 P(S)R 2 (R= Et, n -Pr) gives tetrahedral Mn(II)- dithiophosphinates, (R 2 PS 2 ) 2 Mn, which are dimerized in solution and in the solid state via ligand bridges. The crystal structure of the ethylcomplex is reported. Crystals are orthorhombic, space group Pbca with cell dimensions a = 20.164(4), b = 13.837(3) and c = 11.960(2) A.

Reactions of coordinated ligands: VIII. Phosphinoformic acids RR′PCOOH (R, R′ = organyl, H), the still unknown P-analogues of carbaminic acids, stabilized as ligands in complexes (CO)5MPRR′COOH (M Cr, W)

Abstract Metal carbonyl complexes containing phosphinoformic acids, including the parent compound H2PCOOH, have been made by the following route: (CO)5MPRR′H → (CO)5MPRR′Li → (CO)5MPRR′COOLi → (CO)5MPRR′COOSiMe3 → (CO)5MPRR′COOH (R = organyl, H; M  Cr, W). While the uncoordinated silyl esters RR′PCOOSiMe3 spontaneously decompose to RR′PH, CO2 and Me3SiOH in protic media the last step in the sequence above can be safely brought about by silica gel. So far only chromatography on silica gel has been found to provide the mild conditions necessary to avoid decarboxylation of the ligated esters during protolysis. Some reactions of (CO)5MPRR′COOLi are reported and compared with those of the free ligands RR′PCOOLi. The structures of the complexes have been confirmed by spectroscopic methods (IR, MS, 1H-, 13P-, 13C-NMR).

A Convenient Synthesis of Phosphonic Anhydrides − Trimers [RPO2]3 (R = tert-Butyl, 2-Methylphenyl, 2,4,6-Trimethylphenyl): Their Structures and Reaction Products

By reaction of RP(O)Cl2 with RP(O)(OSiMe3)2, phosphonic anhydrides (RPO2)3 (R = tBu, 2-methylphenyl, 2,4,6-trimethylphenyl) 1a−c are conveniently obtained. In contrast to 1b and 1c, compound 1a is remarkably stable against protolysis. Intermediates of hydrolysis of 1a, namely tris(tert-butyl)triphosphonic acid (2) and bis(tert-butyl)diphosphonic acid (3), can also be isolated in good yield. The structures of 1−3 were determined mainly by NMR spectroscopy (1 H, 13C, 31P). Assuming an energetic preference for the chair conformations in solution, and considering the steric requirements of the bulky substituents R, configurations Ia (point group Cs, two R in equatorial positions) for 1a and b, and IIa (point group C3v, all R equatorial) for 1c are suggested. − Reaction of 1a with N-benzyloxycarbonylglycine (4) in methanol affords strong evidence that in the first step of peptide synthesis with (RPO2)3, a mixed anhydride of triphosphonic acid and the N-protected amino acid is formed. − The crystal structure of 1a (monoclinic, space group P21/n) widely corresponds to the suggested configuration Ia, but reveals an envelope conformation for the six-membered ring with a P3O2 plane in the crystal. In the crystal structure of the octahydrate of the disodium salt of 2 (monoclinic, space group P21/c), it can be seen that the polar end groups of the anions [tBu3P3O7]2− together with the water molecules and the Na+ cations, form hydrogen-bonded double-layers, strictly separated from each other by the non-polar tert-butyl groups of the anions.

Zur Kenntnis Der Organophosphorverbindungen Xxiii1 üBer Alkenylsubstituierte Amino-Bzw. Halogenphosphane Und Versuche Zum Intramolekularen Phosphinidenabfang

Abstract Aminophosphanes RP(NEt2)2 and R2P(NEt2), obtained from alkenyl Grignard compounds RMgX (R =—CH=CH2, —CH2CH=CH2, o(CH2=CH)C6H4—, o(CH2=CHCH2)C6,H4—) and aminochlorophosphanes, reacted smoothly with hydrogen halide to give alkenylhalogenophosphanes RPX2 and R2PX (X = Cl, Br). Properties and reactions of some of these compounds, e.g. with &8 H2O2, H2O and LiAIH4 re reported. On reaction of RPX2 with magnesium only alkenylcyclophosphanes (RP) n were obtained while heterocycles as possible products of an intramolecular reaction of intermediately formed phosphinidenes were not observed. Die aus Alkenylgrignardverbindungen RMgX (R = —CH=CH2, —CH2CH=CH2, o-(CH2=CH)C6H4—, und Aminochlorphosphanen erhaltenen Aminophosphane RP(NEt2)2 und R2 PNEt2 ergebent mit Halogenwassestoff glatt die Halogenphoshane RPX2 und R2 PX (X = Cl, Br). Eigenschaften und Reaktionen einiger dieser Phosphane mit S8, H2O2, H2O und LiAlH4 werden beschrieben. Bei der Umsetzung von RPX2 mit Magnesium bildeten sich ledighch die entsprec...

Reaktionen koordinierter liganden VI. Stabilisierung von RP(OH)2, RPHNEt2 und RPHCl als liganden in (CO)5ML☆

Starting from compounds (CO)5MPRClNEt2 (M = Cr, Mo, W) several new complexes have been obtained in which phosphines—non-existent or having a different tautomeric structure in the free state—are stabilized by coordination to a metal(0) centre. Thus, hydrolysis yields (CO)5CrPR(OH)2, methanolysis (CO)5CrPR(OMe)NEt2 and reduction with LiAlH4 (CO)5MPRHNEt2. The latter were converted into (CO)5MPRHCl with gaseous HCl.

ZUR KENNTNIS DER ORGANOPHOSPHORVERBINDUNGEN XX

Abstract Bifunctional aminophosphanes (Et2N)2P-[CH2] n ,-P(NEt2)2 (n = 1–10) (1) and Et2NP(R)-[CH2] n -P(R)NEt2 (n = 2–4, R = Alkyl, Ph) (2), which are valuable intermediates in organophosphorus synthesis, are obtained by two methods. Because of the marked nucleophility of phosphorus in 1 and 2, reactions with Lewis acids take place very smoothly as is shown by preparation of (Et2N)2P(X)-[CH2]4-(X)P(NEt2) 2(X = O, S, Se, Te, BH3, BBr3) and [(Et2N)2P(CH3)-[CH2]4-(CH3)P(NEt2)2]2+2r. Fission of P[sbnd]bonds by PCl3, MeOH, H2S and CS2 affords Cl2P-[CH2]4-PCl2, (MeO)2P-[CH2]4-P(OMe)2, (MeO)Et2NP-[CH2]4-PNEt2(OMe), the dithiophosphinate [S2P(H)-[CH2]4-(H)PS2]2-2 Et2NH+ 2, and the dithiocarbaminate [Et2NCS2]2P-[CH2]4-P[S] Die Darstellung der bifunktionellen Aminophosphane (Et2N)2P-[CH2] n -P(NEt2)2 (n = 1−10) (1) und Et2N(R)P-[CH2] n -(R)PNEt2 (n = 2–4, R = Alkyl, Ph) (2), die sich als nutzliche Zwischenprodukte bei phosphororganischen Synthesen erwiesen, erfolgte nach zwei Verfahren. Wegen der ausgepragten Nucl...

The radical cation of trimethylphosphine oxide

Abstract The structure of the gaseous long-lived radical cation generated upon electron ionization of trimethylphosphine oxide, (CH 3 ) 3 PO, has been investigated by using ion-molecule reactions in a Fourier transform ion cyclotron resonance mass spectrometer. A radical cation with the connectivity of trimethylphosphine oxide is expected to react by facile electron transfer with triethylamine, pyridine and dimethyl disulfide since all these reactions are highly exothermic. However, no electron transfer reactions were observed. Instead, the radical cation transfers a proton to triethylamine and to pyridine, i.e., acts as a Bronsted acid. Further, the radical cation abstracts CH 3 S from dimethyl disulfide and hence demonstrates behavior characteristic of a distonic ion with a carbon radical center. This reactivity is unprecedented for a radical cation such as (CH 3 ) 3 P + -O with the odd spin located at an oxygen atom. These experimental results indicate that the initially generated radical cation (CH 3 ) 3 P + -O undergoes unimolecular isomerization to (CH 3 ) 2 P + (OH)CH 2 within a millisecond time frame. Ab initio molecular orbital calculations carried out at the unrestricted second-order Moller-Plesset (UMP2/6-31G** + ZPVE) level of theory support this conclusion by predicting that (CH 3 ) 2 P + (OH)CH 2 lies 23 kcal mol −1 lower in energy than (CH 3 ) 3 P + -O. The energy barrier for unimolecular [1,3]-hydrogen atom migration in (CH 3 ) 3 P + -O is estimated to be 24 kcal mol −1 . This study demonstrates that the PO moiety provides a very strong driving force for hydrogen shifts in phosphorus containing radical cations.

Ionic cluster dithiophosphinates [Mo3S4(R2PS2)3py3]+[MI3]−(M=Zn·py, Cd·py, Hg)

Abstract Reactions of clusters Mo 3 S 4 L 4 ( 2 ) (L=R 2 P(S)S − ; R=Et ( a ), Pr ( b )) with MI 2 (M=Zn, Cd, Hg) in the presence of pyridine yieided ionic clusters [Mo 3 S 4 L 3 py 3 ] + [MI 3 py] − (M=Zn ( 9 ), Cd ( 10 ); R=Et ( a ), Pr ( b )) and [Mo 3 S 4 L 3 py 3 ] + [HgI 3 ] − ( 11 ) (L=Pr 2 P(S)S − ), respectively. The cluster cations consist of a triangular array of Mo atoms which are bridged by three S atoms and capped by the fourth S atom. Each of the Mo atoms is chelated by one L and coordinated by one pyridine. 9a crystallizes in the monoclinic space group P 2 1 with Z =2 formula units in the unit cell of dimensions a =1120.9(2), b =1756.3(3), c =1447.3(2) pm, β=105.31(1)°, D c =1.98 mg/ mm 3 . The crystal structure was refined to R = 0.04 using 5599 observed reflections and consists of [Mo 3 S 4 (Et 2 PS) 3 py 3 ] + [ZnI 3 py] − . The coordination number of the Mo atoms is 8. The average distance MoMo is 276.6(2) pm. The Zn atom is coordinated tetrahedrally with average distance ZnI of 259.0(2) and ZnN of 208.8(11) pm.

The ligand field potential of the amido group in transition group ion phosphinothioicamido chelates

Abstract The d-d absorption spectra of some tris-phosphinothioicamido complexes, M[et 2 P(S)NR] 3 (M = Ti, Cr and R = alkyl, cyclo-hexyl or phenyl) in toluene solution have been recorded. Low symmetry splittings of spin-allowed transitions calculated using the angular overlap model refer to the presence of meridional isomers. Comparison with the measured spectra indicates a rather strong metal-amido π bond which explains the relatively small cubic ligand field parameter attributed to this group. For band assignments to ligand field states of lower symmetry, only relative values between σ- and π-antibonding parameters are used in the model.