bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Protecting Group for Constructing Combinatorial Peptide Libraries
Authors: Tamiaki Hitoshi , Obata Tomoyuki , Azefu Yasuo , Toma Kazunori 
Published: September 2002

Abstract
3,4,5-Tris(octadecyloxy)benzyl alcohol, HO–Bzl(OC18)3, was prepared from gallic acid and stearyl bromide. Using conventional step-wise elongation, N,C-protected peptides, Fmoc–AAn–...–AA1–OBzl(OC18)3, were synthesized. The substituted benzyl esters were selectively cleaved by a treatment with 4 M hydrogen chloride in ethyl acetate to give Fmoc–AAn–...–AA1–OH and HO–Bzl(OC18)3. Thus, the substituted benzyl group is effective for the protection of C-terminal carboxyl groups in liquid-phase peptide synthesis. Because the substituted benzyl group has a moderately high molecular weight, Fmoc–AAn–...–AA1–OBzl(OC18)3 can be easily purified by size-exclusion chromatography; all protected peptides are eluted in the void fraction of a Sephadex LH-20 gel-filtration column. The combination of the carboxyl-protecting group Bzl(OC18)3 with simple purification by the gel-filtration gives a novel route for constructing combinatorial peptide libraries in the solution phase.
Synthesis of New Diaryl-Substituted Triple-Decker and Tetraaryl-substituted Double-Decker Lanthanum(III) Porphyrins and Their Porphyrin Ring Rotational Speed as Compared with that of Double-Decker Cerium(IV) Porphyrins
Authors: Ikeda Masato , Takeuchi Masayuki , Shinkai Seiji , Tani Fumito , Naruta Yoshinori 
Published: September 2002

Abstract
Tetraaryl-substituted cerium(IV) double-decker porphyrin (2D), tetraaryl-substituted lanthanum(III) double-decker porphyrin (3D), and diaryl-substituted lanthanum(III) triple-decker porphyrins (4T•Me and 4T•MeO) were newly synthesized and their porphyrin ring rotation rates were systematically estimated by means of a VT NMR spectroscopic method. In 2D the coalescence temperature (Tc) for the porphyrin ring rotation was higher than 110 °C, whereas in 3D it appeared at ca. 0 °C. In diaryl-substituted cerium(IV) double-decker porphyrin (5D) it appeared at 13 °C whereas in 4T•Me and 4T•MeO they were lower than −80 °C. These results consistently support the view that the porphyrin ring rotation rates in lanthanum(III)-based porphyrins are much faster than those in cerium(IV)-based porphyrins. The difference is reasonably explained by the difference in the ion size between these two metal ions. Since these sandwich-type porphyrins can act as novel scaffolds for designing positive allosteric recognition systems, La(III) complexes which feature the faster porphyrin ring rotation should be useful to develop more efficient positive allosteric systems.
Reduction of Organic Halides with Tri-2-furylgermane: Stoichiometric and Catalytic Reduction
Authors: Nakamura Tomoaki , Yorimitsu Hideki , Shinokubo Hiroshi , Oshima Koichiro 
Published: September 2002

Abstract
Tri-2-furylgermane proved to be an effective reagent for the radical reduction of organic halides. Treatment of 1-bromododecane with tri-2-furylgermane in THF at 25 °C in the presence of a catalytic amount of triethylborane afforded dodecane almost quantitatively. Radical cyclization of 2-iodoethanal allyl acetal afforded five-membered products under the same reaction conditions. These reactions proceeded with NaBH4 in the presence of a catalytic amount of germanium hydride. The reaction took place in water as well as in THF to give the corresponding reduced compounds in good yields.
The Rate Enhancement Effect of Protodesilylation of Arylsilane Derivatives
Authors: Utimoto Kiitiro , Otake Yasuyuki , Yoshino Hideaki , Kuwahara Eiko , Oshima Koichiro , Matsubara Seijiro 
Published: September 2002

Abstract
Protodesilylation of the aryl moiety in (p-methoxyphenyl)dimethylsilyl and (2,6-dimethoxyphenyl)dimethylsilyl groups proceeds much faster than that in a phenyldimethylsilyl group under acidic conditions; these aryl groups can be substituted with an F atom to give organosilyl fluoride even in the presence of an acid-sensitive group such as an alkenyl group.
Electroreductive Coupling of Aromatic Acyl Bromides to 1,2-Diketones
Authors: Kise Naoki , Ueda Nasuo 
Published: September 2002

Abstract
The direct electroreduction of aromatic acyl bromides gave aromatic 1,2-diketones. The best result was obtained using a Pb cathode in acetonitrile containing Bu4NClO4 as a supporting electrolyte. Aromatic acyl bromides substituted by an electron-donating group afforded 1,2-diketones in moderate-to-good yields, whereas acylated endiols were formed exclusively from aromatic acyl bromides substituted by an electron-withdrawing group.
Effects of the Proton Content of ZSM-5 and the Amount of Pt on the Hydrodesulfurization Activity of Pt/ZSM-5
Authors: Kurosaka Tadahiro , Sugioka Masatoshi , Matsuhashi Hiromi 
Published: September 2002

Abstract
The effects of the proton content of ZSM-5 and the amount of Pt on the hydrodesulfurization (HDS) activity of Pt/ZSM-5 were studied. The extent of proton exchange was shown to affect the reaction selectivity, the formation of aromatics, the cracking of hydrocarbons, and the dispersion of Pt. The HDS activity depended on the surface area of loaded Pt. A catalyst consisting of 5 wt% Pt supported on a 50% cation exchanged ZSM-5 gave a higher HDS activity than other tested catalysts and a small amount of cracking products.
Structural Study of Crystal Transition from Hexagonal to Rectangular Phase of Lignoceric Acid Monolayers
Authors: Kajiyama Tisato , Tominaga Ryota , Kojio Ken , Tanaka Keiji 
Published: September 2002

Abstract
Crystal transition behavior of lignoceric acid (LA) monolayer was structurally investigated by electron diffraction (ED) in conjunction with scanning force microscopy (SFM). LA molecules form two-dimensional hexagonal crystallites right after one spreads a solution at the air/water interface. The hexagonal-rectangular transition of the LA monolayer was attained by two different experimental procedures: monolayer compression under an isothermal condition and monolayer cooling under an isobaric condition. In the compression process, the hexagonal and rectangular phases coexisted in the monolayer at the surface pressure, π, of 10 mN m−1, which was slightly lower than the plateau pressure, and the subphase temperature of 293 K. When the π exceeded the plateau pressure, the hexagonal phase in the LA monolayer was entirely transformed to the rectangular one. High-resolution SFM showed that the crystal transition from the hexagonal to rectangular phase proceeded via a quasi-disordered phase upon compression. A similar hexagonal-rectangular transition was also observed during the monolayer cooling process at the π of 15 mN m−1. Based on SFM observation, we claimed that the molecular ordering or packing state in the rectangular lattice induced by cooling was better than that by the monolayer compression. Finally, the crystal transition mechanisms for these two procedures were proposed.
Characteristic Phase Transition of [C5H5NH]SbBr4 Having a Hypervalent Bond Studied by Single Crystal X-Ray Diffraction and 2H NMR
Authors: Yamada Koji , Tsuda Takuya , Holst Christian , Okuda Tsutomu , Ehrenberg Helmut , Svoboda Ingrid , Krane Hans-Georg , Fuess Hartmut 
Published: September 2002

Abstract
A characteristic second-order phase transition (Ttr = 251 K) of pyridinium tetrabromoantimonate(III) having hypervalent bonds was studied by means of the single-crystal X-ray diffraction and 2H NMR. The SbBr4- anion in [C5H5NH]SbBr4 forms an infinite zigzag chain of irregular SbBr6 octahedra by sharing two edges. This SbBr4- anion has C2 symmetry on the Sb atom perpendicular to the infinite chain. Hence, each octahedron has one symmetric trans Br(2)-Sb-Br(2) bond and two asymmetric trans Br(1)-Sb···Br(2) above Ttr. However, a structural refinement on Phase II at 110 K revealed a characteristic deformation of one symmetric trans Br(2)-Sb-Br(2) bond to an asymmetric one, i.e., one Sb-Br(2) bond becomes shorter by 0.113(2) Å and the other bond located at the trans position becomes longer by 0.129(2) Å. The structural refinement and the 2H NMR on an N-deuterated analog suggest that the N-H···Br hydrogen bond stabilizes the asymmetric trans Br-Sb···Br bond.
Magnetic Field Effects and Spin Dynamics of Radical Reactions in Solution
Authors: Hayashi Hisaharu , Sakaguchi Yoshio , Wakasa Masanobu 
Published: September 2002

Abstract
A pulsed magnet which is useful for the research of chemical reactions has recently been constructed by our group. Here, the world record of the maximum magnetic field (30 T) has been attained in this research area. An optical detected X-band ESR apparatus has also been developed by our group. The world’s best sensitivity and resolution have been realized in this apparatus. In this account, we review our recent results on new magnetic field effects and spin dynamics obtained with such novel methods as described above for radical reactions at room temperature in solution. In Section 1, typical mechanisms of MFEs on radical pairs such as the Δg mechanism and the relaxation mechanism are explained as the introduction of this review. In Section 2, the saturation of MFEs due to the Δg mechanism observed for radical pairs generated from the photoreduction of 4-methoxybenzophenone with benzenethiol in fluid solutions under ultrahigh fields are described. In Section 3, the saturation and reversion of MFEs due to the relaxation mechanism observed for radical pairs generated from the photoreduction of carbonyl and quinone compounds in micellar solutions under ultrahigh fields are reviewed. In Section 4, the first observation of MFEs on the reactions of three-spin systems generated photochemically in solution are introduced. In Section 5, we describe spin dynamics of radical pairs studied with our optically detected ESR apparatus for radical pairs generated from the photoreduction of carbonyl and quinone compounds in micellar solutions.
Monofunctionalized C60 Ions: Their Generation, Stability, and Reactions
Authors: Kitagawa Toshikazu , Takeuchi Ken’ichi 
Published: September 2002

Abstract
Though numerous investigations have appeared on the reduced and oxidized forms of parent C60, investigations on C60 ions that contain exohedral functional group(s) have been rather few. This account deals with the chemistry of such ions, in particular, the chemistry of monofunctionalized species RC60− and RC60+. Studies of the anions RC60− were initiated early in the history of the fullerene chemistry, and they are generally considered appreciably stable carbanions. This account focuses on our recent synthesis of a hydrocarbon salt and ionically dissociable hydrocarbons which contain the C60 framework. These are unusual classes of hydrocarbons that could be obtained by making use of the high thermodynamic stability of a hydrocarbon anion t-BuC60−. Some of the properties which are characteristic of these hydrocarbons are also discussed. In contrast, studies of the chemistry of the cation RC60+ have only recently been launched. In this account, advances in the studies of these cations, including observations of their existence, the evaluation of their stabilities, and the role of these cations as a reactive intermediate, are described.
In Situ Time-Resolved Energy-Dispersive XAFS Study on the Reduction Processes of Cu–ZSM-5 Catalysts
Authors: Yamaguchi Aritomo , Shido Takafumi , Inada Yasuhiro , Kogure Toshihiro , Asakura Kiyotaka , Nomura Masaharu , Iwasawa Yasuhiro 
Published: September 2002

Abstract
The reduction process of Cu–ZSM-5 was investigated by a time-resolved energy-dispersive XAFS (DXAFS) technique. The spectra were recorded every second and the entire spectra were analyzed to elucidate the dynamic change of the local structure around the Cu species. Two Cu–ZSM-5 samples with different Cu loadings were prepared by an ion-exchange method followed by calcination. In the low-loading sample (84% ion-exchanged), Cu2+ cations dispersed isolatedly in the channels of ZSM-5, while in the high-loading sample (104% ion-exchanged) CuO particles were formed. The isolated Cu2+ cations were reduced to isolated Cu2+ cations at 400–450 K and the Cu+ ions were reduced to Cu0 at 550–650 K. The curve fitting analysis of the DXAFS data revealed that Cu4–6 clusters were initially formed in the reduction process. The clusters went out to the outer surface and grew into big particles. On the contrary, the CuO particles on the outer surfaces were reduced directly to Cu0 metallic particles at ca. 450 K. The dynamic structure change around the Cu species in the zeolite during the reduction with H2 was monitored in situ by DXAFS technique for the first time.
Additive Effect of 1-Propanol and 2-Propanol on Molecular Organization of H2O in the Water-Rich Region: Excess Chemical Potential, Partial Molar Enthalpy and Volume of 1-Propanol in 1-Propanol–2-Propanol–H2O at 25 °C
Authors: Hu Jianhua , Chiang Wesley Min-Da , Westh Peter , Chen Daniel Heng Chi , Haynes Charles Allen , Koga Yoshikata 
Published: September 2002

Abstract
Excess chemical potential, μ1PE, partial molar enthalpy, H1PE and volume of 1-propanol, V1PE, were determined as a function of mole fraction of 1-propanol, x1P, in mixed solvents of aqueous 2-propanol with various initial mole fraction of 2-propanol, x2P0. The 1-propanol–1-propanol interaction functions, H1P–1PE ≡ N(∂H1PE/∂n1P), and V1P–1PE ≡ N(∂V1PE/∂n1P), were evaluated by graphical differentiation. The x1P-dependence of all these quantities indicates that 1-propanol and 2-propanol modify the molecular organization of H2O in the same and additive manner in the water-rich region. The additive effect of 1-propanol and that of 2-propanol are in the ratio of (0.07/0.08).
NH3 Dissociative Adsorption on Si(100)-(2×1) Surface: A B3LYP Quantum Chemical Cluster Model Study
Authors: Xu Xin , Kang Song-Yun , Yamabe Tokio 
Published: September 2002

Abstract
Dissociative adsorption of ammonia on the Si(100)-(2×1) surface has been investigated using the hybrid density functional B3LYP method and the Si9H12 one-dimer cluster model of the surface. The adsorption geometries and the reaction energetics from NH3(a) to NH2(a) and H(a) have been studied with Si basis sets varying from the standard all electron 6-31G(d) to the LanL2DZ with effective core potential, while keeping NH3 basis sets as 6-31G(d,p) in all cases. It was found that B3LYP/LanL2DZ is a reasonable level of theory for the calculations of not only the geometries, but also the reaction energetics. This provides a cost-effective way to extend the size of the Si cluster models and to study in details the energetics of the whole reaction path. Based on the experimental and theoretical results available, we recommend an “optimal” bond geometry of NH2(a) and H(a) on the Si(100)-(2×1) surface to be: Si–Si (symmetric dimer) 2.42 Å, Si–N 1.75 Å, Si–H 1.50 Å, N–H 1.01 Å, Si–Si–N 115°, Si-N-H 118°, Si–Si–H 111°, H–N–H 109°. The calculated results on the reaction energetics are in general agreement with the experimental findings as well as the previous theoretical ones.
Dual Photochromic Properties of 4-Dialkylamino-2-hydroxychalcones
Authors: Matsushima Ryoka , Fujimoto Shuichi , Tokumura Kunihiro 
Published: September 2002

Abstract
4-Dialkylamino-2-hydroxychalcones [3-(4-dialkylamino-2-hydroxyphenyl)-1-(substituted phenyl)-2-propen-1-ones] undergo reversible E/Z-photoisomerization in good quantum yields (0.2–0.4) in neutral aprotic solvents. The absorption bands of the photo-Z-isomers are significantly red-shifted from the E-isomers. By addition of acid, the photo-Z-isomers are converted to the flavylium ions with competitive reversion to the E-isomers. In aqueous ethanol solution, photochromic interconversion between chalcones and flavylium ions takes place rather slowly and less extensively.
Selenium Analogs of Tetrathiapentalene Derivatives with Long Alkyl Chains
Authors: Aragaki Masanobu , Kimura Shinya , Katsuhara Mao , Kurai Hiroyuki , Mori Takehiko 
Published: September 2002

Abstract
A novel selenium-containing bis-fused tetrathiafulvalene donor, C2TET-TS-TTP (2-[4,5-bis(ethylthio)-1,3-dithiol-2-ylidene]-5-(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-1,3,4,6-tetrathiapentalene), has been synthesized. The ClO4−, BF4−, and PF6− salts of C2TET-TS-TTP are isostructural, having uniform β-type structures. These salts are essentially metallic down to low temperatures.
Mass-Spectrometric Study on Ion-Molecule Reactions of CH5+, C2H5+, and C3H5+ with C8–C18 1-Olefins in an Ion Trap
Authors: Tanaka Yuki , Tsuji Masaharu 
Published: September 2002

Abstract
Chemical ionization of 1-olefins (CxH2x : x = 8–18) by the CH5+, C2H5+, and C3H5+ ions has been studied under a reactant-ion selective mode of an ion-trap type of GC/MS. In all the reactions, alkyl CyH2y+1+ (y = 3–x) and alkenyl CyH2y−1+ (y = 3–x) ions were observed. For long-chain reagents (x = 11–18), the CyH2y+1+ and CyH2y−1+ distributions peaked at C4 or C5 and C7, respectively, which were essentially independent of the reactant hydrocarbon ions. On the basis of observed distributions and calculated thermochemical data, it was concluded that the major reactions for the formation of CyH2y+1+ were proton transfer to a C=C bond and hydride-ion abstraction from the alkyl portion in the CH5+ reactions, proton transfer to a C=C bond in the C2H5+ reactions, and addition to a C=C bond in the C3H5+ reactions, while the major reactions for the formation of CyH2y−1+ were hydride-ion abstraction in the CH5+ reactions, alkanide-ion abstraction in the C2H5+ reactions, and addition to a C=C bond in the C3H5+ reactions.
Dinuclear Zinc Complexes of Phenol-Based “End-off” Compartmental Ligands: Synthesis, Structures and Phosphatase-Like Activity
Authors: Abe Ko-ji , Izumi Jun , Ohba Masaaki , Yokoyama Takusi , Okawa Hisashi 
Published: September 2002

Abstract
The phenol-based compartmental ligands of the “end-off” type, 2,6-bis{N-[2-(dimethylamino)ethyl]iminomethyl}-4-methylphenol (HL1), 2-{N-[2-(dimethylamino)ethyl]iminomethyl}-6-{N-methyl-N-[2-(dimethylamino)ethyl]aminomethyl}-4-bromophenol (HL2), 2,6-bis{2-[(2-pyridyl)ethyl]iminomethyl}-4-methylphenol (HL3) and 2-[N,N-di(2-pyridylmethyl)aminomethyl]-6-{N-[2-(dimethylamino)ethyl]iminomethyl}-4-methylphenol (HL4), have formed dinuclear zinc complexes: [Zn2(L1)(AcO)2]PF6 (1), [Zn2(L1)(NCS)3] (2), [Zn2(L2)(AcO)2]PF6 (3), [Zn2(L2)(NCS)3] (4), [Zn2(L3)(AcO)2]PF6 (5), [Zn2(L3)(NCS)3] (6), [Zn2(L4)(AcO)2]ClO4 (7), [Zn2(L4)(AcO)(NCS)2] (8) and [Zn2(L4)(NCS)3] (9). The crystal structures of 1, 5•(DMF)0.5(2-PrOH)0.5, 7•CHCl3, 8•(2-PrOH) and 9•3CHCl3 have been determined. Complexes 1 and 5•(DMF)0.5(2-PrOH)0.5 have a di-μ-acetato-μ-phenolato-dizinc(II) core comprised of two square-pyramidal Zn centers. 7•CHCl3 has a similar dinuclear core, but it is comprised of one square-pyramidal Zn and one pseudo-octahedral Zn. 8•(2-PrOH) has a μ-acetato-μ-phenolato-dizinc(II) core with a unidentate thiocyanato-N group on each Zn. 9•3CHCl3 exists in two different crystals: one has a μ-thiocyanato-N-μ-phenolato-dizinc(II) core, whereas the other has a μ-phenolato-dizinc(II) core. The diacetato complexes, 1, 3, 5 and 7, are stable in solution. Hydrolytic activities of the complexes toward tris(p-nitrophenyl) phosphate (TNP) have been studied in aqueous DMF by means of UV-visible spectroscopic and 31P NMR methods. Complexes 1, 3 and 5 have an activity to hydrolyze TNP into bis(p-nitrophenyl) hydrogenphosphate (HBNP) in aqueous DMF. In contrast, 7 showed little hydrolytic activity toward TNP in aqueous DMF.
Assignment of d–d Transitions of Square Planar [CuIIN4] Complexes Containing Imidate and Amine Ligands by Means of Polarized Crystal Spectra.
Authors: Akitsu Takashiro , Komorita Seiko , Urushiyama Akio 
Published: September 2002

Abstract
Square planar [CuN4] copper(II) complexes, Rb2[Cu(succim)4]•2H2O (1), trans-[CuL2(R-chea)(S-chea)] (2), trans-[CuL2(R-chea)2] (3), (succim = succinimidate, L = 5,5-diphenylhydantoinate, and chea = 1-cyclohexylethylamine) were prepared and crystal structures were determined. Crystal data for 1 are monoclinic with space group C2/m; a = 16.279(4), b = 8.382(3), c = 8.297(3) Å; β = 93.13(3) °; V = 1130.4(6) Å3; Z = 2. Crystal data for 2 are monoclinic with space group P21/c; a = 8.485(2), b = 9.7854(8), c = 26.334(4) Å; β = 92.83(1) °; V = 2183.8(5) Å3; Z = 2. Crystal data for 3 are monoclinic with space group P21; a = 8.472(2), b = 9.803(2), c = 26.331(6) Å; β = 92.67(2) °; V = 2184.6(8) Å3; Z = 2. The polarized crystal electronic spectra were determined for square planar [CuN4] 1, 2, and 3 and distorted square planar [CuN4] trans-[CuL2(R-phenea)(S-phenea)] (4) and trans-[CuL2(R-phenea)2][CuL2(S-phenea)2] (5) (phenea = 1-phenylethylamine). These spectra were deconvoluted by Gaussian curve fitting by considering selection rules for electric dipole transitions. The 3d orbital orders were determined to be dx2−y2 &gt; dxy &gt; dz2 &gt; dyz,dzx for 1, dx2−y2 &gt; dxy &gt; dz2 &gt; dyz &gt; dzx for 2 and 3, and dx2−y2 &gt; dxy &gt; dz2 &gt; dyz &gt; dzx for 4 and 5 by means of polarized crystal spectra and angular overlap model (AOM) calculations. Since the dz2 → dx2−y2 transition could be observed separately for 4 for the first time, the present assignment could be established certainly. Distortion of [CuN4] chromophores decreases the peak wave numbers for a series of trans-[Cu(imidate)2(amine)2] complexes. The results of 1, 2, and 3 suggest that lone pairs of imidate ligands destabilize the dxy orbital by distributing in the [CuN4] plane.
Kinetics and Mechanisms of the Axial Ligand Substitution Reaction of the Head-to-head 2-Pyridonato-bridged cis-Diammineplatinum(III) Dinuclear Complex
Authors: Saeki Nami , Hirano Yuji , Sasamoto Yasunari , Sato Ichiro , Toshida Tsuyoshi , Ito Sousei , Nakamura Noriko , Ishihara Koji , Matsumoto Kazuko 
Published: September 2002

Abstract
The following successive axial ligand substitution reactions of the head-to-head (HH) 2-pyridonato-bridged cis-diammineplatinum(III) dinuclear complex ([(H2O)Pt(NH3)2(μ-C5H4NO)2Pt(NH3)2(H2O)]4+) with halide ions X− (X− = Cl− and Br−) to give monohalogeno and dihalogeno complexes were studied kinetically:
[(H2O)Pt(NH3)2(μ-C5H4NO)2Pt(NH3)2(H2O)]4++X− →← [(H2O)Pt(NH3)2(μ-C5H4NO)2Pt(NH3)2(X)]3++H2O,
[(H2O)Pt(NH3)2(μ-C5H4NO)2Pt(NH3)2(X)]3++X− →← [(X)Pt(NH3)2(μ-C5H4NO)2Pt(NH3)2(X)]2++H2O.
The acid dissociation constant (Kh1) of the axial aqua ligand in the HH dimer and the formation constants (K1X and K2X) of the monohalogeno and dihalogeno complexes were determined spectrophotometrically to be −log(Kh1/M) = 1.71 ± 0.04; log(K1Cl/M−1) = 5.93 ± 0.02, log(K2Cl/M−1) = 3.71 ± 0.00 for the reaction with Cl−, and log(K1Br/M−1) = 6.20 ± 0.05, log(K2Br/M−1) = 4.55 ± 0.01 for the reaction with Br−. The two platinum atoms are nonequivalent in the HH dimer, in which the first deprotonation occurs selectively to the water molecule on the Pt(N4) atom and the first nucleophilic substitution with X− occurs preferentially to the Pt(N2O2) atom, where the atoms in parentheses are the coordinating atoms. The first water substitution with X− proceeds via two similar substitution paths, whereas the second substitution proceeds through two dissimilar paths: one is a simple substitution path and the other is via dissociation of the water molecule, providing a coordinatively unsaturated complex. These reaction paths are reasonably explained by the relative strength of the trans effect of the water, hydroxide, and halide ions in the monohalogeno complexes.
Copper(II) Complexes Resulting from the Oxygenation of (2,9-Dimethyl-1,10-phenanthroline)copper(I) Chloride in the Presence of Dimethylformamide
Authors: Oyaizu Kenichi , Ueno Masayoshi , Li Hong , Tsuchida Eishun 
Published: September 2002

Abstract
The oxygenation of (2,9-dimethyl-1,10-phenanthroline)copper(I) chloride in THF, followed by a treatment with DMF and acidification with HCl, afforded dichloro[2-(dimethylamino)(hydroxy)methyl-9-methyl-1,10-phenanthroline]copper(II) and (aqua)dichloro(2,9-dimethyl-1,10-phenanthroline)copper(II) quantitatively.