Karl Minten

The coordination chemistry of manganese. : Part VII. The preparation and spectroscopic characterisation of some manganese(II) complexes of triphenylphosphine of unusual stoicheiometry, Mn(PPh3)X2

Abstract Novel manganese(II) complexes of triphenylphosphine, Mn(PPh 3 )X 2 (X = Cl, Br, I, NCS), have been isolated and studied by a number of spectroscopic techniques. The basic structure in the solid state is pseudotetrahedral and the complexes may be oligomeric. The Mn(OPPh 3 )(NCS) 2 complex, synthesised for comparative purposes, differs from Mn(PPh 3 )(NCS) 2 in a number of important ways.

The coordination chemistry of manganese. Part VI. [1–4]. Bis(tetrahydrofuran)manganese(II) halide complexes; synthesis and characterisation

Abstract The solid state structures of Mn(THF) 2 X 2 (THF = tetrahydrofuran; X = Cl, Br, I) appear to be halide-bridgedpseudooctahedral polymers which do not exhibit EPR signals. The EPR-active Mn(THF) 2 (NCS) 2 is a pseudotetrahedral monomer. In tetrahydrofuran solution the Mn(THF) 2 X 2 complexes react with PPhMe 2 to form a complex which can reversibly absorb/desorb molecular oxygen in a manner analogous to the authentic haem analogues Mn(PPhMe 2 )X 2 . However, reaction of Mn(THF) 2 X 2 with PPhMe 2 in acetonitrile, followed by exposure to dioxygen, results in rapid decomposition to an EPR-inactive species, presumably manganese(III), accompanied by production of some OPPhMe 2 . An authentic sample of Mn(PPhMe 2 )Br 2 in acetonitrile also undergoes similar decomposition on exposure to dioxygen. Polarographic and other characterisation data are reported for the Mn(THF) 2 X 2 complexes.

The coordination of small molecules by manganese(II): III. The reversible binding of carbon monoxide by MnX2(PR3) (R3 PhMe2, PhEt2, Prn.3, X Cl, Br, I) in the solid state and in solution

Abstract The manganese(II) phosphine complexes MnX 2 (PR 3 )(PR 3  PPhMe 2 , X  Cl, Br, I; PR 3  PPhEt 2 , PPr n 3 , X  Cl, Br) have been found to react with carbon monoxide in a 1/1 ratio to form “MnX 2 (CO)(PR 3 )” in the solid state and in tetrahydrofuran (THF) solution. The reaction may be reversed either by a pressure drop or a temperature rise, and the gas released is shown to be carbon monoxide by mass spectral methods. The rate of reaction of MnX 2 (PR 3 ) with carbon monoxide appears to be both phosphine and halide dependent. In THF solution ESR measurements indicate that the CO adduct is the pseudooctahedral MnX 2 (THF) 2 (CO)(PR 3 species, whereas in the solid state it is the pseudotetrahedral MnX 2 (CO)(PR 3 ). The ν(CO) infrared band appears at 2100–2085 cm −1 in the carbon monoxide adducts.

Working haem analogues; reversible oxygenation of the manganese–tertiary phosphine complexes MnLX2

The reversible oxygenation of the complexes MnLX2(L = tertiary phosphine, but not PPh3, X = action) has been investigated; these complexes resemble haemoglobin and myoglobin to a remarkable degree as reversible dioxygen carriers.

Nickel(II), palladium(II) and cobalt(II) complexes of the substituted tritertiary arsine, 2-chloroethylbis(3-dimethylarsinopropyl)arsine

Abstract The substituted tritertiary arsine, 2-chloroethyl-bis(3-dimethylarsinopropyl)arsine, forms Ni(trias)X 2 (X = Cl, Br, I), which are assigned tetragonal pyramidal pentacoordinate structures. The Pd(trias)Cl 2 species is best assigned as a planar [Pd(trias)Cl]Cl coordination moiety. Both [Co(trias)Br] 2 [CoBr 4 ] and [Co(trias)Br]ClO 4 contain pseudotetrahedral cations, but [Co(trias) 2 ](ClO 4 ) 2 is unlike any four-coordinate or six-coordinate cobalt(II) entity and is assigned a pentacoordinate structure containing a tridentate and a bidentate ligand. The donor properties of trias are compared to that of similar tridentate ligands.

Synthesis and characterization of the dimeric [Mn(salen)(CO)]2(ClO4)2[salen =N,N′-ethylenebis(salicylideneaminato)], a carbonyl complex of a metal in the +3 oxidation state

The synthesis and characterization of [Mn(salen)(CO)]2(ClO4)2[salen N,N′-ethylenebis(salicylideneaminato)], the first carbonyl complex of a first row transition metal in the +3 oxidation state, are reported; the formation of such a complex is critically dependent on the nature of the polymethylene chain in the Schiffs base ligand.

Trans-chelation in transition metal complexes: Synthesis and characterization of platinum(II) complexes of bis(disphenylarsino)alkanes

Abstract Cis and trans complexes of the type Pt(ligand)Cl 2 (ligand = Ph 2 As(CH 2 ) n AsPh 2 , n = 6–12, 16) have been synthesized, together with the bromo, iodo and thiocyanato derivatives for n = 10 and 12. The cis complexes are essentially dimeric. The complexes have been characterized by elemental analyses, infrared and proton NMR spectroscopy, solid state reflectance and visible/UV spectroscopy and vapor phase osmometry. Formation of the cis or trans isomer for the complexes Pt(ligand)Cl 2 is critically dependent on the choice of complex precursor: potassium tetrachloroplatinate(II) yields the cis isomer, whilst Zeises salt gives the trans isomer. The bromo, iodo and thiocyanato derivatives prepared via an exchange reaction give cis complexes. Evidence is presented for the existence of PtNCS and PtSCN linkages both in the solid state and in solution for the thiocyanato derivatives. Product distribution and stereochemistry in all of the complexes are discussed in terms of the factors governing trans chelation.

Tertiary phosphine adducts of manganese (II) dihalides. The X-ray crystal structure of di-iodo(phenyldimethylphosphine)manganese(II)

AnX-Crystal structure determination of Mnl2(PPhMe2)reveals iodide-bridged polymer chains consisting of alternating tetrahedral (Mnl4)and pseudo-octahedral (trans-MnP2I4)units.

The X-ray crystal; structure of trans-tri-iodobis(trimethylphosphine)manganese(III). The first example of a trigonal bipyramidal manganese(III) tertiary phosphine complex

The reaction of Mnl2(PMe3)with dioxygen leads to the formation of the trigonal bipyramidal bisphosphine manganese(III) complex, trans-Mnl3(PMe3)2; no phosphine oxidation is observed.