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A series of cobalt(III) complexes containing 2-cyanoethylphosphines, [Co(Me2dtc)2{P(CH2CH2CN)nPh3-n}2]BF4{Me2dtc-: N,N-dimethyldithiocarbamate; n= 1 (1), 2 (2), and 3 (3)} have been prepared, and their molecular structures in the crystals and in solution have been characterized. X-ray analysis revealed that all complexes isolated as single-crystals were the trans-isomers. The Co–P bond lengths for the 2-cyanoethylphosphines in complexes 1–3are almost invariant to the number of 2-cyanoethyl substituent groups. Unlike related complexes with other monodentate P-donor ligands, complexes 1–3in solution showed dissociation and isomerization equilibriums, which were achieved immediately after dissolving the crystals. These characteristic features of the complexes would result from the weak s-donor and p-acceptor abilities of 2-cyanoethylphosphines. Furthermore, mixing of complex 1and NaN3in acetonitrile gave cis-[Co(Me2dtc)2(N3){P(CH2CH2CN)Ph2}] quantitatively, and refluxing the mixture resulted in the phosphine–tetrazolate complex, [Co(Me2dtc)2(Ph2PCH2CH2CN4-?2P,N1)] (4).

A series of new cobalt(III) phosphine complexes of trans-[Co(dtc)2(PMe3-nPhn)2]BF4(dtc = N,N-dimethyldithiocarbamate; n= 0, 1, 2 or 3) and cis-[Co(dtc)2(PMe3or PMe2Ph)2](BF4or PF6) have been prepared and their crystal structures and spectroscopic properties have been investigated. It is found that the Co–S bond lengths vary with steric and electronic factors of the P-ligands; i.e. (1) the intramolecular p–p stacking interaction between the dtc plane and the phenyl ring of the P-ligand, and (2) the electronic transinfluence of the trans-positioned P-ligand. The strength of electronic transinfluence decreases as PMe3> PMe2Ph > P(OCH2)3CEt in accordance with the order of s-donicity strengths. In the series of trans-isomers, the electronic transinfluence is competitive with the steric requirement of the phosphine to elongate the mutually transCo–P bonds. The steric transinfluence via the equatorial dtc ligands for such an elongation of the Co–P bonds seems to be negligible, which is in sharp contrast to the situation for via pentane-2,4-dionate (acac) ligands in the analogous complexes, trans-[Co(acac)2(PMe3-nPhn)2]PF6. This is probably due to the compactness of dtc and the resulting open space at the Co atom. The fact that the Co–P bond lengths in the dtc complexes are shorter than those in the acac complexes is reflected in the larger stability toward hydrolysis of the dtc complexes. In the UV-vis absorption spectra, the degenerate splitting component (a1Eg) of the first d–d transition band of trans-[Co(dtc)2(PMe3-nPhn)2]+is observed at almost the same position (within 300 cm-1) as that of the corresponding acac complexes, while the transition energies of the P-to-Co LMCT of these two series of complexes are rather different (at least 2700 cm-1) from each other. Furthermore, the first and the second d–d transition bands of cis-[Co(dtc)2(PMe3or PMe2Ph)2]+are observed at lower energy than those of cis-[Co(dtc)2{P(OMe)3}2]+in spite of a weaker s-donor of phosphite. The separation of the first and the second d–d transition bands of the P(OMe)3complex is remarkably smaller than the separation of the bands of the PMe3one, being indicative of a further reduction of the interelectronic repulsion in the P(OMe)3complex.

A new phosphine ligand, 8-(dimethylphosphino)quinoline (Me2Pqn), and its palladium(I or II) complexes, [PdX2(Me2Pqn)] (X = Cl (1a), Br (1b), and I (1c)), [Pd(Me2Pqn)2](BF4)2(2b), and [Pd2Cl2(Me2Pqn)2] (3), have been prepared and characterized. The structures of 2band 3have been determined by X-ray analysis. The crystal data and final Rvalues are: for 2b, FW = 658.42, monoclinic, P21/n, a= 17.453(2), b= 10.453(2), c= 14.928(2) Å, β= 105.63(1)°, V= 2622.8(5) Å3, Dx= 1.667 Mg m−3, and Z= 4, R= 0.071 for 3908 reflections (|Fo| ≥ 3σ(|Fo|)); for 3, MW = 662.64, monoclinic, P21/n, a= 16.429(1), b= 12.191(1), c= 12.821(1) Å, β= 92.673(8)°, V= 2565.1(4) Å3, Dx= 1.714 Mg m−3, and Z= 4, R= 0.056 for 5136 reflections (|Fo| ≥ 3σ(|Fo|)). In 2bthe square coordination plane formed by two long Pd–N (2.138(9) and 2.135(8) Å) and two Pd–P bonds (2.243(3) and 2.237(3) Å) is slightly distorted towards tetrahedral geometry, the dihedral angle between the two chelate planes formed by the Pd, P, and N atoms being 10.3(2)°. 3is a dinuclear complex with a Pd–Pd bond (2.542(1) Å), Me2Pqn chelates to one Pd(I) center, and the N donor atom occupies the transposition to the Pd–Pd bond. The dihedral angle between the two coordination planes linked by the Pd–Pd bond is nearly a right angle, 82.13(6)°.

The title complex, prepared from a reaction of [(IrCp*Cl)2(µ-Cl)2] with K2CrO4in water, has been characterized via a single-crystal X-ray diffraction study. In the solid state the tri-µ-hydroxo-diiridium complex cations, the dichromates having the staggered conformation, and the water molecules of crystallization are entirely connected by hydrogen bonds forming a novel two-dimensional layer structure.

The iridium(III) complexes containing (2-aminoethyl)dimethylphosphine (edmp) or (2-aminoethyl)diphenylphosphine (edpp) were prepared. Crystal structures of fac-[Ir(edmp)3]Cl3·5H2O (2), trans(Cl,Cl),cis(P,P)-[IrCl2(edpp)2]BF4(3), and ?(lel3)- and ?(ob3)-[Ir(R,R-chxn)3](NO3)3·3H2O (4and 5; chxn = trans-1,2-cyclohexanediamine) were determined by single-crystal X-ray diffraction. Crystal data and final Rvalues are: for 2, FW = 703.7, triclinic, , a= 11.718(2), b= 13.199(1), c= 9.482(1) Å, a= 91.44(1), ß= 105.86(1), ?= 90.53(1)°, V= 1410.0(2) Å3, Dx= 1.66 Mg m-3, and Z= 2, R= 0.039 for 5410 reflections. For 3, FW = 808.5, triclinic, , a= 11.465(1), b= 13.694(1), c= 10.049(1) Å, a= 94.764(6), ß= 92.197(8), ?= 102.807(8)°, V= 1530.5(2) Å3, Dx= 1.75 Mg m-3, and Z= 2, R= 0.035 for 5978 reflections. For 4, FW = 774.9, hexagonal, P63, a= 13.005(1), c= 10.221(2) Å, V= 1497.1(3) Å3, Dm= 1.71(2), Dx= 1.72 Mg m-3, and Z= 2, R= 0.020 for 1063 reflections. For 5, hexagonal, FW = 774.9, P63, a= 13.359(1), c= 9.848(2) Å, V= 1522.0(3) Å3, Dm= 1.70(2), Dx= 1.69Mg m-3, and Z= 2, R= 0.015 for 1105 reflections. The average Ir–N bond length of 2.167(6) Å in 2is longer by 0.077(6) Å than those in 4and 5. The structural data of the corresponding cobalt(III) and rhodium(III) complexes show that the order of the strength of the trans influence of the –PMe2group in edmp is CoIII< IrIII< RhIII. In 3, the elongation of the metal–nitrogen bond length by the trans influence of the –PPh2group in edpp is smaller than that of the –PMe2group in 2, and the elongation is nearly the same as those in the corresponding cobalt(III) and rhodium(III) complexes. The absorption spectra of the two series of complexes, fac-[M(edmp)3]3+and trans(Cl,Cl),cis(P,P)-[MCl2(edpp)2]+(M = CoIII, RhIII, and IrIII) are compared and Shimura’s spectrochemical parameters for iridium(III) are discussed.

A series of dinuclear complexes containing Me2Ppy ( = 2-(dimethylphosphino)pyridine) as a bridging ligand, [MM'X2(µ-Me2Ppy)2] (M, M' = Pd(I), Pt(I); X = Cl, Br, and I), have been prepared by reactions between [MX2(Me2Ppy-P)2] and [M'2(dba)3] (dba = 1,5-diphenyl-1,4-pentadien-3-one). In these reactions it has been found by 31P{1H} NMR studies that a dimeric head-to-head isomer was formed in the first place and then isomerized to a head-to-tail isomer. The reactions for analogous Ph2Ppy ( = 2-(diphenylphosphino)pyridine) complexes have been also examined in the same manner. The monomeric Pd(II) complexes reacted more rapidly than did the corresponding Pt(II) complexes in these dimerization and isomerization reactions. For each halogeno series of the Me2Ppy and Ph2Ppy complexes, it seems that the dimerization occurs faster in the order of Cl < Br < I, while the order is reversed in the isomerization, Cl > Br > I. The Me2Ppy complexes isomerized to a head-to-tail isomer more rapidly than did the Ph2Ppy complexes, indicating a larger trans effect of Me2Ppy than Ph2Ppy.

A reaction of [Cp*Ir(2-Spy)(N3)] (Cp*= pentamethylcyclopentadienyl; 2-Spy = 2-pyridinethiolate) with two equivalents of methyl iodide afforded the diiodo complex bearing 2-MeSpy, [Cp*IrI2(2-MeSpy)] (3). From X-ray crystallography and IR spectroscopy, the S atom of 2-MeSpy is coordinated to the metal ion in the solid state. In CD2Cl2, complex 3exhibited a dissociation equilibrium of 2-MeSpy similar to the corresponding thioanisole complex of [Cp*IrI2(MeSPh)].