Übergangsmetallphosphidokomplexe. VII. Ringgrößeneffekte bei den NMR‐Daten von Übergangsmetallphosphor‐Vier‐ und Sechsringkomplexen

Abstract

Ein Vergleich entsprechender NMR‐Daten von [cpNiPH2]2 1 und [cpNiPH2]3 2, von [(CO)4MnPH2]2 3 und [(CO)4MnPH2]3 4 sowie von [(CO)4MnPF2]2 5 und [(CO)4‐MnPF2]3 6 zeigt, daß besonders die Kopplungskonstante der Phosphorkerne untereinander JPMP (M = Ni, Mn) sowie sämtliche chemischen Verschiebungen stark von der Ringgröße beeinflußt werden. Die relevanten Kopplungskonstanten zwischen den Kernen 1H, 31P und 19F wurden durch Computersimulation der entsprechenden Spinsysteme höherer Ordnung ermittelt.

Synthesis, Structure, and Deprotonation of a Mesitylphosphido-Bridged Cyclopentadienylnickel(II) Dimer

“…Spectral simulation of the AA′XX′ spin system 5 gives 2 J PP ) 432. 6 Hz, 1 J PH ) 318.3 Hz, 3 J PH ) -20.5 Hz, and 4 J HH ) 5.3 Hz. These coupling constants are similar to those reported 6 for [NiCp(µ-PH 2 )] 2 , which are shown along with 31 P NMR data for other complexes reported here in Table 1.…”

“…6 Hz, 1 J PH ) 318.3 Hz, 3 J PH ) -20.5 Hz, and 4 J HH ) 5.3 Hz. These coupling constants are similar to those reported 6 for [NiCp(µ-PH 2 )] 2 , which are shown along with 31 P NMR data for other complexes reported here in Table 1. The P-H protons give rise to an identical pattern (δ 3.62, CD 2 Cl 2 ) in the 1 H NMR spectrum, but only the more intense four middle lines are observed.…”

“…As with 2 and 3, complex 5 was not further characterized or isolated. Treatment with MeI (Scheme 2) gives the symmetrical dimer [NiCp(µ-PMeMes)] 2 (6), which is also formed (in low yield) in the direct reaction of dianion 3 with methyl iodide. Analysis of reaction mixtures by 31 P NMR (Table 1) suggests that both anti and syn isomers 6a,b (Chart 1) are formed (the assignments were made on the basis of the chemical shift trends observed for 1a/b and 4a/b), but this mixture converts to pure 6b over the course of 1 day.…”

Synthesis and Skeletal Transformations of Trinuclear Palladium and Nickel Phosphido Complexes

“…This change for phosphanes is comparable to that found for the phosphido‐bridged systems on going from [Pd 2 P 2 ]Cl 2 to [Pd 3 P 3 ]Cl 3 (in both systems, the P atom is also part of a five‐membered chelate that should cause deshielding). Other representatives are [M 2 (PH 2 ) 2 ] and [M 3 (PH 2 ) 3 ] with δ ( 31 P) = –305 and –108 ppm for M = CpNi and –194 and –131 ppm for M = (OC) 4 Mn 1c. Another indication that phosphanes and phosphido systems behave similarly is provided by [CpFe(CO) 2 PPh 2 ],34 a terminal phosphido group with δ ( 31 P) = 8.3 ppm.…”