A phosphorus-31 nuclear magnetic resonance study of triphenylphosphine oxide exchange on magnesium(II) and zinc(II)

1981 ◽  
Vol 34 (2) ◽  
pp. 283 ◽  
Author(s):  
SF Lincoln ◽  
DL Pisaniello ◽  
TM Spotswood ◽  
MN Tkaczuk
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Ligand Exchange ◽  
Exchange Process ◽  
Triphenylphosphine Oxide ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Data Set ◽  
Typical Data ◽  
Apparent Equilibrium ◽  
Acid Character

31P n.m.r, studies show that the rate of triphenylphosphine oxide exchange on [Zn(O=PPh3)4]2+ in CD2Cl2 solution is independent of [O=PPh3]free. A typical data set is: kex(200 K) = 611 ± 37 s-1, ΔH‡ = 32.0 ± 0.7 kJ mol-1 and ΔS‡ = -28.3 ± 3.4 J K-1 mol-1 for a solution in which [Zn(O=PPh3)42+] and [O=PPh3]free are 0.163 and 0.639 mol dm-3 respectively, where kex = exchange rate/(4[Zn(O=PPh3)42+])= (kBT/h)exp(-ΔH‡/RT)exp(ΔS‡/R) Similarly the rate of ligand exchange on [Mg(O=PPh3)5]2+ is shown to be independent of [O=PPh3]free and a typical data set is kex'(220 K) = 38 ± 4 s-1, ΔH‡ = 73.7 ± 1.8 kJ mol-1 and ΔS‡ = 123 ± 8 J K-1 mol-1 for a solution in which [Mg(O=PPh3)52+] and [O=PPh3]free are 0.0813 and 0.276 mol dm-3 respectively. The ligand exchange process on both species is considered to proceed through a D mechanism. The apparent equilibrium constant K = [Mg(O=PPh3)52+]/ ([Mg(O=PPh3)42+][O=PPh3] ≥ 150 dm3 mol-1 but in contrast [Zn(O=PPh3)2+ appears to be the only stable zinc(II) species in solution. It is concluded that these data probably reflect the hard acid character of magnesium(II) and the intermediate acid characteristics of zinc(II).

A preparative and phosphorus-31 nuclear magnetic resonance study of the coordination of three phosphate based ligands to dioxouranium(VI)

1982 ◽  
Vol 35 (7) ◽  
pp. 1489
Author(s):  
AE Bakas ◽  
AM Hounslow ◽  
SF Lincoln ◽  
NJ Maeji
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ligand Exchange ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
The Third ◽  
Nuclear Magnetic

The three species [UO2{OP(OMe)(NMe2)2}4](ClO4)2, [UO2{OP(OMe)2(NMe)}5] (C1O4)2 and [UO2{OPMe2Ph)]5] (ClO4)2 have been isolated and their CD2Cl2 solutions studied by means of 31P n.m.r. An equilibrium between [UO2L52+ and [UO2L4]2+ exists in solutions of the first two species. In solutions of the third species [UO2L5]2+ predominates and ligand exchange proceeds through a dissociative D mechanism for which kex (285 K), characterizing a single ligand, is 1830 � 250 s-1, ΔH‡ 82.15 � 1.8 kJ mol-1 and ΔS‡ 106 � 16 JK-1 mol-1.

A 19F nuclear magnetic resonance study of the exchange of the fluoro ligands of the tetrafluoroberyllium(II) ion

1977 ◽  
Vol 30 (2) ◽  
pp. 271 ◽  
Author(s):  
SF Lincoln ◽  
AC Sandercock ◽  
DR Stranks
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Exchange Rate ◽  
Magnetic Resonance ◽  
Exchange Process ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Rate Law ◽  
The Exchange Rate ◽  
Nuclear Magnetic

A 19F N.M.R. study is reported of the exchange of the fluoro ligands of [BeF4]2-. The exchange rate law is: ����������� rate = kobs4[BeF42-] = k'4[BeF42-]+ k''4[BeF42-][BeF3H2O-] where k'(298 K) = 69�3 s-1, ΔH‡ = 30�3 kJ mol-1, ΔS‡ = -110�10 J mol-1 K-1 and k''(298 K) = (1.6�0.5)×103 dm3 mol-1 s-1, ΔH‡ = 26�3 kJ mol-1, ΔS‡ = - 96�9 J mol-1 K-1. The k' exchange process appears to be predominantly dissociative in nature, and the k'' exchange process apparently proceeds through a fluoro bridged species [Be2F7]2-.

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