The five-coordinate geometry is an important factor in phosphoryl group transfer, particularly for phosphate ester hydrolysis. In the following review we analyze the five-coordinate geometries for a range of VO4X coordination spheres with regard to their structure from the point of view of square pyramidal or trigonal bipyramidal geometries. The actual differences for the coordination environment of the reported small molecule structures are compared to the coordination environment of vanadate complexed to a protein tyrosine phosphatase (PTP) with four coordinating O atoms and one S atom. These considerations demonstrate that actual differences between the coordination environments are very small and presumably less critical than generally anticipated. This analysis suggests that it is a combination of structural and electronic properties leading to the perfect combination of reactivity and stability for the potent protein phosphatase inhibitor complex, thus confirming the fact that some other geometries have been reported.

Trigonal Bipyramidal or Square Pyramidal Coordination Geometry? Investigating the Most Potent Geometry for Vanadium Phosphatase Inhibitors

The coordination chemistry of hydrated and solvated vanadium(III), oxovanadium(IV), and dioxovanadium(V) ions in the oxygen-donor solvents water, dimethyl sulfoxide (DMSO), and N,N′-dimethylpropyleneurea (DMPU) has been studied in solution by extended X-ray absorption fine structure (EXAFS) and large-angle X-ray scattering (LAXS) and in the solid state by single-crystal X-ray diffraction and EXAFS The hydrated vanadium(III) ion has a regular octahedral configuration with a mean V–O bond distance of 199 A In the hydrated and DMSO-solvated oxovanadium(IV) ions, vanadium binds strongly to an oxo group at ca 16 A The solvent molecule trans to the oxo group is very weakly bound, at ca 22 A, while the remaining four solvent molecules, with a mean V–O bond distance of 20 A, form a plane slightly below the vanadium atom; the mean O═V—Operp bond angle is ca 98° In the DMPU-solvated oxovanadium(IV) ion, the space-demanding properties of the DMPU molecule leave no solvent molecule in the trans position to

https://pubs.acs.org/doi/pdf/10.1021/ic300202f

A Coordination Chemistry Study of Hydrated and Solvated Cationic Vanadium Ions in Oxidation States +III, +IV, and +V in Solution and Solid State

While most high and medium oxidation state (O.S. ≥ 3) metal and non-metal fluorides and oxide fluorides are strong Lewis acids, exploration of their coordination chemistry with neutral ligands has been limited and mostly non-systematic. This is despite the very different properties conferred on the acceptor centre by the small electronegative fluoride ligands compared to the heavier halides. This article sets out these key differences, discusses possible synthetic routes, the key characterisation techniques, and appropriate bonding models. Current knowledge of the coordination chemistry of d, f and p-block fluorides and oxide fluorides with neutral ligands (with donor atoms drawn from Groups 15 and 16 and including N-heterocyclic carbenes) is then presented and discussed, and the differences in properties compared to complexes containing the heavier halides are illustrated. The emphasis is on work published post 1990, but earlier work is also included as essential background and where no more recent information exists. Attention is drawn to unexplored areas meriting investigation and to possible applications of these complexes.

Medium and high oxidation state metal/non-metal fluoride and oxide–fluoride complexes with neutral donor ligands

A series of new silver(I)-containing MOFs [Ag2(tr2ad)2](ClO4)2 (1), [Ag2(VO2F2)2(tr2ad)2]·H2O (2), [Ag2(VO2F2)2(tr2eth)2(H2O)2] (3), and [Ag2(VO2F2)2(tr2cy)2]·4H2O (4) supported by 4-substituted bi...

Ag(I)/V(V) heterobimetallic frameworks generated from novel-type {Ag2(VO2F2)2(triazole)4} secondary building blocks: a new aspect in the design of SVOF hybrids.

The first soft donor adducts of TiF4, [TiF4(diphosphine)] (diphosphine = o-C6H4(PMe2)2, R2P(CH2)2PR2, R = Me or Et) have been prepared from [TiF4(MeCN)2] and the diphosphines in rigorously anhydrous CH2Cl2, as extremely moisture sensitive yellow solids, and characterised by multinuclear NMR (1H, 31P, 19F), IR and UV/vis spectroscopy. The crystal structure of [TiF4{Et2P(CH2)2PEt2}] has been determined and shows a distorted six-coordinate geometry with disparate Ti–FtransF and Ti–FtransP distances and long Ti–P bonds. Weaker soft donor ligands including Ph3P, Ph2P(CH2)2PPh2, o-C6H4(PPh2)2, Ph2As(CH2)2AsPh2, o-C6H4(AsMe2)2 and iPrS(CH2)2SiPr do not form stable complexes with TiF4, although surprisingly, fluorotitanate(IV) salts of the previously unknown doubly protonated ligand cations [LH2][Ti4F18] (L = o-C6H4(PPh2)2, o-C6H4(AsMe2)2 and iPrS(CH2)2SiPr) are formed in some cases as minor by-products. The structure of [o-C6H4(PPh2H)2][Ti4F18] shows the first authenticated example of a diprotonated o-phenylene-diphosphine. The synthesis and full spectroscopic characterisation are reported for a range of TiF4 adducts with hard N– or O-donor ligands for comparison purposes, along with crystal structures of [TiF4(thf)2], [TiF4(Ph3EO)2]·2CH2Cl2 (E = P or As), and [TiF4(bipy)].

Taking TiF4 complexes to extremes - the first examples with phosphine co-ligands

[VO2F(L–L)] (L–L = 2,2′-bipyridyl, 1,10-phenanthroline, Me2N(CH2)2NMe2) and [VO2F(py)2] (py = pyridine) have been prepared from the corresponding [VOF3(L–L)] or [VOF3(py)2] and O(SiMe3)2 in MeCN solution. VO2F (itself made from VOF3 and O(SiMe3)2 in MeCN) forms [Me4N][VO2F2] with [Me4N]F, but does not react with neutral N- or O-donor ligands. VO2Cl, prepared from VOCl3 and ozone, reacts with 2,2′-bipyridyl or 1,10-phenanthroline to form [VO2Cl(L–L)], with pyridine or pyridine-N-oxide (L) to produce [VO2Cl(L)2], and with OPPh3 or OAsPh3 (L′) gives [VO2Cl(L′)]. A second product from the OPPh3 system is the ionic [VO2(OPPh3)3][VO2Cl2] containing a trigonal bipyramidal cation. Neither VO2F nor VO2Cl form isolable complexes with MeCN, thf or MeO(CH2)2OMe, and both are reduced by P-, As-, S- or Se-donor ligands. [Ph4As][VO2X2] (X = F or Cl) react with 2,2′-bipyridyl to form [VO2X(2,2′-bipyridyl)], but similar reactions with weaker O-donor ligands fail. The complexes have been characterised by IR, multinuclear NMR (1H, 19F, 51V or 31P) and UV-visible spectroscopy. X-ray crystal structures are reported for [VO2F(py)2], [VO2Cl(L)2] (L = py or pyNO) and [VO2(OPPh3)3][VO2Cl2].

Alethea Leung

Papers

Synthesis, chemistry and structures of complexes of the dioxovanadium(V) halides VO2F and VO2Cl