Inorganic Chemistry Communications (v.3, #10)

Cobalt(II) phosphine complexes stable in aqueous solution: spectroscopic and kinetic evidence for low-spin Co(II)P6 and Co(II)P3S3 with tripodal 1,1,1-tris(dimethylphosphinomethyl)ethane by Satoshi Iwatsuki; Hiroo Kato; Kenji Obeyama; Shigenobu Funahashi; Nobuyoshi Koshino; Kazuo Kashiwabara; Takayoshi Suzuki; Hideo D Takagi (501-504).
Co(II) species produced by the controlled potential electrochemical reduction of Co(III)P3S3 and Co(III)P6 complexes with 1,4,7-trithiacyclononane and tripodal 1,1,1-tris(dimethylphosphinomethyl)ethane in aqueous solution were characterized at ambient temperature by the EPR and spectrophotometric methods: the Co(II)P6 and Co(II)P3S3 species are in the low-spin t2g 6eg 1 state with large Jahn–Teller distortion. Kinetic studies of the redox reactions involving these Co(III)/(II) species revealed that the electron self-exchange reactions for the Co(III)/(II) couples are very fast (k ex∼104 dm3 mol−1 s−1), which is consistent with the results for other low-spin/low-spin Co(III)/(II) couples. It was concluded that the nephelauxetic effect of the P donor atom stabilizes the low-spin state in Co(II).
Keywords: Cobalt(II); Spin state; EPR study; Kinetics; Electron transfer;

Irradiation of [SbV(tpp)(OH)2]+ (tpp=dianion of 5,10,15,20-tetraphenylporphyrin) at 298 K in argon saturated dichloromethane under steady state conditions results in the formation of the highly oxidising π-radical cation [SbV(tpp)(OH)2]2+ with spectral characteristics corresponding to a 2A2u electronic ground state.
Keywords: Porphyrins; Radical cations; Oxidations; Photochemistry; Enzyme models;

Intramolecular hydrogen bonding and cation π-interactions can be used to favour cis isomers of [W(CO)4(PRPh2)2](R=2-pyridyl or phenyl) type complexes. The changes in isomerization equilibrium can be switched by protonation or deprotonation of the 2-pyridyl groups.
Keywords: Hydrogen bonding; Cation-π interaction; Cis–trans isomerism; Phosphane ligand; NMR spectroscopy; Crystal structures;

A novel functionalized P,C,P pincer ligand complex by Jost C Grimm; Christiane Nachtigal; H.-G Mack; William C Kaska; Hermann A Mayer (511-514).
Reaction of 3,5-di(bromomethyl)nitrobenzene with di-t-butylphosphine and subsequent treatment with sodium acetate gives the novel functionalized P,C,P pincer ligand 2. Heating an isopropanol/water solution of 2 with iridium(III)chloride results in the iridium hydrochloride complex 3. This complex was characterized by X-ray structure analysis in the solid state, NMR spectroscopy in solution, and density functional calculations in the gas phase.
Keywords: Pincer ligands; Iridium complexes; X-ray structure; Quantum chemical calculations;

Asymmetric hydroformylation of vinylarenes with rhodium diphosphite catalyst by Pedro Uriz; Elena Fernández; Nuria Ruiz; Carmen Claver (515-519).
Chiral diphosphite based on binaphthol, which chelate with rhodium complexes forming a nine-membered ring, led to an efficient hydroformylation of vinylarenes, (e.e.. up to 46%), at moderate pressure and temperature reaction conditions. High pressure 1H NMR experiments to elucidate intermediate metal species have been performed.
Keywords: Asymmetric hydroformylation; Vinyl arenes; Rhodium; Diphosphite; High pressure 1H NMR;

The hydrothermal reaction of Cu2O, Na3VO4, H2O3PCH2PO3H2, 2,2′-bipyridine-4,4′-dicarboxylic acid, and H2O in the mole ratio 2.5:1.7:10:1.0:2700 at 200°C for 42 h yields [{(bpy-dicarb)Cu}2{V3O3(OH)2(H2O)}(O3PCH2PO3)2]·2H2O (1·2H2O). The structure of 1 is a two-dimensional sheet constructed from pentanuclear {V3Cu2O3(OH)2(H2O)}8+ units linked by (O3PCH2PO3)4− ligands into a network. Crystal data: C13H14N2O14P2V1.5Cu, triclinic, P 1 ̄ : a=7.8993(7) Å, b=11.0417(9) Å, c=11.857(1) Å, α=100.845(1)°, β=98.400(2)°, γ=105.290(2)°, V=958.7(1) Å3.

The new complexes [CpM(L2)NCCH2Fc]PF6 (M=Fe 1, Ru 2; Fc=ferrocenyl), have been prepared from reaction of CpM(L2)X and the ligand Fc–CH2CN 3 in methanol and in the presence of NH4PF6. The compounds were characterized by elemental analysis as well as spectroscopic methods. Electrochemical as well as near-IR measurements suggest a weak metal–metal interaction for the Fe(II)–Fe(III) complex. Hush parameters for this mixed-valence complex suggest a class II Robin–Day type with a moderate metal–metal interaction similar to that observed in the related pyridine bridged systems (η 5-C5H5)Fe-η 5-C5H4–C5H4N–ML n . The unusual electron transfer through a insulating CH2 group is the first such example for an asymmetric binuclear system.
Keywords: Iron binuclear complexes; Mixed valence; Ferrocene derivatives; Electron transfer;

Lewis acidity of tris(pentafluorophenyl)borane: crystal and molecular structure of B(C6F5)3·OPEt3 by Michael A Beckett; David S Brassington; Simon J Coles; Michael B Hursthouse (530-533).
The synthesis and characterisation (IR, multielement NMR spectroscopy) of B(C6F5)3·L {L=CH3CO·OEt (1), Et3PO (2)} are described together with a single-crystal X-ray diffraction study of 2. The latter reveals an angular B–O–P linkage {161.04(16)°} with BO and PO bondlengths of 1.533(3) and 1.4973(17) Å, respectively. Lappert’s Δν(CO) and Gutmann’s acceptor number (AN) methods have been applied to 1 and 2 to assess the relative Lewis acidity of B(C6F5)3 which is confirmed as weaker than BF3. A strong linear correlation has been obtained for Gutmann’s AN and Childs’ 1H NMR Lewis acidity scales.
Keywords: Acceptor number; Borane; Lewis acidity; X-ray structure; Organophosphine oxide;

The tris(2-mercaptoimidazolyl)borate lead complex, [TmPh]2Pb, may be synthesized by reaction of Pb(ClO4)2 with 2 equivalents of [TmPh]Li. The molecular structure of [TmPh]2Pb has been determined by X–ray diffraction, revealing that it possesses an unusual structure with an inverted η 4-coordination mode for the [TmPh] ligand which includes a Pb···H–B interaction.

A chloride-bridged one-dimensional Cu(II) coordination polymer is prepared by the treatment of N-benzoyl-N′-(2-pyridyl)thiourea with a large excess of Cu(II)Cl2 in ethanol solution via oxidative cyclization and coordinate polymerization.
Keywords: Thioureas; Cu(II)complex; Oxidative cyclization; Coordinate polymerization.;

A novel one-dimensional coordination polymer, {[Cu(dien)(dimb)](ClO4)2} n [dien=diethylenetriamine; dimb=1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene] was synthesized by treatment of [Cu(dien)(im)](ClO4)2 (im=imidazole) with the dimb ligand. The complex was characterized by X-ray crystallography and electrospray mass spectrometry. The coordination geometry around Cu(II) is distorted square-based pyramid with N5 donor set.
Keywords: Crystal structure; Copper(II) complex; 1D coordination polymer; Electrospray mass spectrometry;

The complex [RuCl2(p-cymene)]2 reacts with 1-(3,5-dimethyl)pyrazolyldiphenylphosphine (P(Me2Pz)Ph2) to give the complex RuCl2(p-cymene)(P(Me2Pz)Ph2). This compound reacts with ROH molecules (R=H, Me and p-Tol) to give [RuCl(p-cymene)(Me2HPz)(PPh2OR)]Cl (R=H, Me and p-Tol) complexes, which contain both Me2HPz and PPh2OR coordinated molecules.
Keywords: Ruthenium complexes; Ruthenium–arene complexes; Pyrazoles; Pyrazolyl–phosphine ligands;

A heteronuclear trimetallic complex {[(3,2,3-tet)Ni(μ-CO3)Ni(3,2,3-tet)][(3,2,3-tet)Cu]}4+ (3,2,3-tet=N,N-bis(3-aminopropyl)ethylenediamine) has been prepared by the reaction of Ni(II), 3,2,3-tet, Na2CO3 and Cu(3,2,3-tet)(ClO4)2 in situ. The complex is composed of two units, [(3,2,3-tet)Ni(μ-CO3)Ni(3,2,3-tet)]2+ and [Cu(3,2,3-tet)]2+, which are linked by hydrogen bonding. The carbonate ion in the former unit acts as a bis-μ-bidentate ligand and adopts cis arrangement, and the resulting dinuclear complex has cis-β configuration for both Ni(II) ions.
Keywords: Heteronuclear trimetallic complex; {[(3,2,3-tet)Niμ(-CO3)Ni(3,2,3-tet)][(3,2,3-tet)Cu]}4+; Hydrogen bonding; Bis-μ-bidentate ligand;