Undergo Ligand Exchange Reactions Research Articles

Free radicals formed in the reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine and 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)phenoxazinyl radical with certain organometallic compounds

1. 1H-1-Oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine undergoes ligand exchange reactions and behaves as a spin trap for metal-centered radicals, as a result of which stable paramagnetic complexes are formed with delocalization of the unpaired electron in the organic ligand. 2. Paramagnetic complexes are also formed as the result of a reaction between potassium salt (IA) and triphenyl-tin and triphenyl-lead monochlorides.

Effects of phenoxide ligation: Synthesis and characterization of the [Mo 2Fe 6S 8(SEt) 3(OPh) 6] 3− ion

Reaction of phenol with an alkylthiolate-ligated double cubane complex effects phenolate substitution at the terminal positions; the product can be isolated as its benzyltriethylammonium salt. The phenolate cluster possesses unaltered magnetic properties and blue shifted optical spectra, and undergoes ligand exchange reactions with electrophiles as expected for terminal phenolate substitution. Increased isotropic proton NMR shifts and large negative shifts in corresponding first and second reduction potentials are consistent with increased donation of electron density to the [MoFe 3S 4] 3+ cores for phenolate versus thiophenolate terminal ligands to iron. Similar behavior has been observed for Fe 4S 4, Fe 2S 2 and MoS 2Fe systems.

Tris(phosphan)-Nickel(0)-Ethen-Komplexe (dmpe)(PR3)Ni(C2H4). Molekülstruktur des (dmpe)(PØ3 )Ni(C2H4)/ Tris(phosphane)-nickel(0)-ethene Complexes (dmpe)(PR3)Ni(C2H4). Molecular Structure of (dmpe)(PO3)Ni(C2H4)

Abstract Synthesis and properties of tris(phosphane)(ethene)nickel(0) complexes (dmpe)(PR3)Ni(C2H4) (R = CH3(4), c-C6H11(5), and C6H5 (6)) are reported. In solution. 4-6 are thermolabile and undergo ligand exchange reactions affording tetrakis(phosphane)nickel(0 ) and bis(phosphane)- (ethene)nickel(0) complexes. 1H, 13C, and 31P NMR data of 4-6 confirm the tetrahedral geometry around nickel. For 6 , the crystal and molecular structure has been determined by X-ray crystallography.

LIGAND EXCHANGE REACTIONS OF ANTIMONY(III)O,O-DISUBSTITUTED PHOSPHORODITHIOATES WITH NICKEL SALTS

Abstract Antimony(III) tris-(O,O-dialkyl phosphorodithioates) undergo ligand exchange reactions with nickel(II) chloride or nickel(II) octanoate in tetrahydrofuran solution to give nickel(II) bis-(O,O-dialkyl phosphorodithioates). The rates of the exchange reactions with nickel(II) chloride have been measured, and the rate constants can be correlated with polar substituent constants by use of the Taft-Hammett equation. The results suggest that the ligand exchange reactions occur by an initial SN2 type of attack of chloride ion on the antimony atom of the antimony(III) tris-(O,O-dialkyl phosphorodithioates).

Metal complexes of sulphur ligands. Part V. Dialkyl-, diaryl-phosphinodithioato-and NN-dialkyldithiocarbamato-complexes of ruthenium(II)

Complexes of general formula [Ru(S–S)2L2][(S–S)–=–S2PR2(R = Me, Et, Ph), –S2CNMe2; L = PPh3, PMe2Ph, PMePh2, P(OPh)3etc.] have been synthesised by the reaction of various ruthenium(II) and (III) tertiary phosphine and phosphite complexes with Na(S–S). For (S–S)–=–S2PR2, these compounds are readily carbonylated to give the monocarbonyls [Ru(S2PR2)2L(CO)]. However, the dicarbonyls can be synthesised directly, from ruthenium carbonyl halides and NaS2PR2. Although the corresponding dithiocarbamates are resistant to carbonylation, all these compounds undergo ligand exchange reactions with ligands of greater basicity (L′) to give either [Ru(S–S)2LL′] and/or [Ru(S–S)2L′2]. All these compounds have been thoroughly examined by i.r., mass, and 1H n.m.r. spectroscopy and the latter indicates a cis-configuration. Most of these compounds also show temperature variable 1H n.m.r. spectra, attributable to facile interconversion of optical enantiomers (for the –S2PR2 compounds), restricted rotation about the –CN bond (for the –S2CNMe2 compounds), and, in some cases, hindered rotation about the ruthenium–phosphorus bonds.Finally, for [Ru(S2PR2)2(PMe2Ph)2], carbonylation gives, in addition to [Ru(S2PR2)2(PMe2Ph)CO], two isomers of formula [Ru(S2PR2)2(PMe2Ph)2CO]. The structures of these compounds have been established by 1H, 31P n.m.r., and double resonance studies and a general mechanism of carbonylation for these compounds is proposed.