published_or_final_version / Chemistry / Master / Master of Philosophy

This thesis reports the study of molecular and electronic structure of iridium containing diatomic molecules using the technique of laser ablation/reaction with free jet expansion and laser induced fluorescence (LIF) spectroscopy. The iridium containing diatomic molecules studied in this research are iridium phosphide (IrP), iridium boride (IrB) and iridium oxide (IrO). These molecules were produced by the reaction of Ir atoms ablated by a pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser and 1% PH3, 0.5% B2H6 and 6% N2O gases to produce IrP, IrB and IrO molecules respectively. Pulsed tunable lasers: a dye laser and an optical parametric oscillator (OPO) laser system were used to cover the spectral region between 390 and 650 nm in obtaining electronic transitions of the iridium containing diatomic molecules. The recorded electronic spectra of IrP, IrB and IrO molecules yields information on the bond length and electronic structures. For the IrP molecule, five electronic transitions, namely the [21.2] 3Σ+ – X1Σ+, [21.7]1Σ+ – X1Σ+, [23.6] 0+ – X1Σ+, [23.7] 0+ – X1Σ+ and [23.9] 0+ – X1Σ+ transitions, have been recorded and analyzed. The bond length, r0, and the ΔG1/2 of the ground state of 193IrP molecule was determined to be 1.9928? and 569.77 cm-1 respectively. For the IrB molecule, four new electronic transition systems, namely the [18.8]3Δ3 – X3Δ3, [21.1]3Φ4 – X3Δ3, [22.8]3Φ3 – X3Δ3 and [22.4]1Φ3 – a1Δ2 transitions, were observed and analyzed rotationally. The bond lengths, r0, of the upper states of 193IrB were determined to be within 1.72 and 1.80?. For the IrO molecule, five electronic transitions from two different lower states were recorded and analyzed, namely the [17.6] 2.5 – X2Δ5/2, [17.8] 2.5 – X2Δ5/2, [21.5] 2.5 – X2Δ5/2, [22.0] 2.5 – X2Δ5/2 and [21.9] 3.5 – Ω = 3.5 transitions. The ground state of IrO has been confirmed to be 25/2. The bond length, r0, and the ΔG1/2 of the ground state of 193IrO molecule was determined to be 1.726 A and 900.00 cm-1 respectively. For all the transitions observed, rotationally-resolved transition lines were fit to theoretical models to obtain molecular constants for both the upper and lower electronic states. Typical molecular transition linewidths obtained was larger than 0.1cm-1, which is likely to be due to unresolved hyperfine structure in the rotational lines. In addition, the observation of isotopic spectrum confirmed the assignment of vibrational quantum number. Molecular and electronic structures of these iridium containing diatomic molecules were discussed using a simple molecular orbital theory. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 69-75) Also available in print.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 75-79).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 125-130). Also available via the Internet.

本論文主要研究銥和銠卟啉絡合物與鹵代苯 (ArX, X = Cl, Br, I)的碳-鹵鍵(Ar-X)的斷裂反應及其應用。本論文分為四個部分：（1）銠卟啉絡合物與鹵代苯(ArX, X = Cl, Br, I)之間的碳-鹵鍵(Ar-X)斷裂反應；（2）氟氯化苯的碳-氟鍵(Ar-F)與碳-氯鍵(Ar-Cl)斷裂的競爭反應；（3）氟取代基對金屬（銥和銠）-芳香碳(M-Ar)鍵強弱的影響；以及（4）銥卟啉氟硼荧絡合物的合成。 / 第一部分闡述了銠卟啉絡合物(Rh(ttp)Cl)與鹵代苯(ArX, X = Cl, Br, I) 之間的碳-鹵鍵 (Ar-X) 斷裂反應以及反應機理。在鹼性條件下，無論富電子還是缺電子的鹵代苯都能與Rh(ttp)Cl反應，生成Ar-X鍵斷裂的產物──銠卟啉芳基絡合物(Rh(ttp)Ar) 。機理研究顯示， Rh(ttp)Cl 首先與氫氧根離子反應生成Rh(ttp)OH，進而通過二聚反應生成[Rh(ttp)]₂。[Rh(ttp)]₂在加熱條件下與Rh(ttp)自由基可以互相轉化，產生的Rh(ttp)自由基與鹵代苯進行原位取代反應，生成銠卟啉芳基絡合物(Rh(ttp)Ar)和鹵素自由基。鹵素自由基可以和另一個Rh(ttp)自由基反應生成Rh(ttp)X，在氫氧根離子存在的條件下，Rh(ttp)X將再次轉化為Rh(ttp)OH繼續反應。 / 第二部分描述了氟氯化苯中碳-氟鍵(Ar-F)與碳-氯鍵(Ar-Cl)斷裂的競爭反應。機理研究顯示碳-氟鍵(Ar-F)斷裂的中間體是M(por)⁻，而碳-氯鍵(Ar-Cl)斷裂的中間體是MII(por)。因此，我們可以通過改變反應條件而控制生成物。例如，在較低溫度下和強鹼性的極性溶劑中，以M(por)⁻前體作為反應物，可以獲得較多的碳-氟鍵(Ar-F)斷裂的產物；而在較高溫度下和弱鹼性的非極性溶劑中，可以獲得較多的碳-氯鍵(Ar-Cl)斷裂的產物。 / 第三部分敘述了間位氟取代基對金屬-芳香碳(M-Ar)鍵的增強作用。有間位氟取代基的金屬（銥，銠）卟啉芳基絡合物(M(ttp)ArF)是最穩定的同分異構體。在250°C條件下，當反應30天後，Ir(ttp)C₆H₄F的三個異構體達到平衡狀態，其鄰位:間位:對位的比例大約為0:5:1。理論計算的結果也顯示Ir(ttp)(3-fluorophenyl)相對Ir(ttp)(2-fluorophenyl)和Ir(ttp)(4-fluorophenyl)有更低的能量。氟取代基在鄰位時，氟與卟啉之間空間位阻較大，減弱了金屬-芳香碳(M-Ar)鍵的鍵能。與氟取代基在對位相比，在間位時具有更好的吸電子效應，從而增加了金屬-芳香碳(M-Ar)鍵的極性，增強了金屬-芳香碳(M-Ar)鍵鍵能。 / 第四部分描述了利用碳-鹵鍵 (Ar-X) 的斷裂，合成銥卟啉氟硼荧絡合物的反應。銥卟啉氟硼荧絡合物的產率可以達到70%。銥卟啉氟硼荧絡合物在生物成像和放射療法都有潛在的應用。銥卟啉氟硼荧絡合物是用金屬自由基與氟硼荧反應合成的。 / This thesis focuses on the reaction scopes, mechanistic investigations and applications of base-promoted aryl carbon-halogen (Ar-X) bond cleavage with iridium and rhodium porphyrin complexes. This thesis is divided into four parts: (1) Ar-X (X = Cl, Br, I) bond cleavage with Rh(ttp)Cl; (2) competitive Ar-F and Ar-Cl bond cleavage with iridium and rhodium porphyrins; (3) fluorine substituent effect on the M-Ar (M = Ir, Rh) bond strength; and (4) synthesis of iridium porphyrin BODIPY complexes. / Part I describes the reaction scopes and mechanism of Ar-X (X = I, Br, Cl) bond cleavage with Rh(ttp)Cl (ttp = 5,10,15,20-tetratolylporphyrinato dianion). Under basic conditions, both electron-rich and electron-deficient ArX undergo Ar-X bond cleavage to give Rh(ttp)Ar in good yields. [with diagram] / The mechanistic investigations suggest that RhIII(ttp)Cl first undergoes ligand substitution by OH- to give RhIII(ttp)OH, which forms [RhII(ttp)]₂ through reductive dimerization. RhII(ttp) radical, which is in equilibrium with [RhII(ttp)]₂, cleaves the Ar-X (X = I, Br, Cl) bond through metalloradical ipso-substitution and gives RhIII(ttp)Ar and X radical. X radical recombines with another RhII(ttp) radical to generate RhIII(ttp)X, which gives back RhIII(ttp)OH through ligand substitution by OH-. [with diagram] / Part II describes the competitive Ar-F and Ar-X (X = Cl, Br) bond cleavage reactions of fluorochlorobenzenes with iridium and rhodium porphyrin complexes. Mechanistic studies suggest that M(por)⁻ is the intermediate for the Ar-F bond cleavage while MII(por) is the intermediate for the Ar-X bond cleavage. By taking advantage of the difference in mechanisms of the Ar-F and Ar-X bond cleavages, the selectivity of bond cleavage can be controlled by varying the reaction conditions. The Ar-F bond cleavage is favored in a polar solvent with a stronger base at lower temperatures with M(por)⁻ precursor, and the Ar-X bond cleavage is favored under non-polar conditions with a weaker base and at higher temperatures. [with diagram] / Part III describes the meta-fluorine substituent effect on strengthening the M-Ar (M = Ir, Rh) bond of M(ttp)ArF. M(ttp)ArF with meta-fluorine substituent are the most stable isomers among the isomeric Ar-H bond cleavage products. At 250 °C for 30 days, the three isomers of Ir(ttp)C₆H₄F reached an equilibrium with o : m : p = 0 : 5 : 1. The theoretical calculations also suggest that Ir(ttp)(3-fluorophenyl) is of lower energy than Ir(ttp)(2-fluorophenyl) and Ir(ttp)(4-fluorophenyl). The ortho-fluorine substituent exhibits steric effect which weakens the M-Ar bond. The meta-fluorine, which is more electron-withdrawing than para-fluorine, enhances the polarity of the M-C(ipso) bond and thus strengthens the M-Ar bond. [with diagram] / Part IV describes the application of Ar-I bond cleavage with Ir(ttp)(CO)Cl in synthesizing iridium porphyrin boron-dipyrromethene (BODIPY) complexes, which are potential photosensitizers for biological imaging and photodynamic therapy. The clinically interested iridium porphyrin BODIPY complexes have been prepared by a radical process of metalloradical with BODIPY. [with diagram] / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Qian, Yingying. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references. / Abstracts also in Chinese.

The iridium(III) methyl diarylphosphide complexes, Ir(CH₃PR₂-[N(SiMe₂CH₂PPh₂)₂] (2a: R = phenyl, 2b: R = meta-tolyl) had been prepared previous to this work. The iridium(III) dimethylphosphide complex, Ir(CH₃)PMe₂-[N(SiMe₂CH₂PPh₂)₂], 2c, is readily prepared in situ by transmetallation of the Ir(CH₃)I[N(SiMe₂CH₂PPh₂)₂] with KPMe₂ at -30°C. The synthesis of the phenylphosphide complex Ir(CH₃)PHPh[N(SiMe₂CH₂PPh₂)₂], 2d, involves deprotonation of the six-coordinate iridium(III) phenylphosphine complex, Ir(CH₃)I-(PH₂Ph)[N(SiMe₂CH₂PPh₂)₂], with KO¹Bu. Thermolysis of 2a and 2b yields the six-coordinate iridium(III) cyclometallated hydride complexes fac-Ir(ɳ²-CH₂PR₂)H[N(SiMe₂CH₂PPh₂)₂], 3a and 3b. The dimethylphosphide complex 2c undergoes the same rearrangement to afford 3c but more rapidly. Thermolysis of 3a-3c yields the square planar iridium(I) phosphine complexes of the formula, Ir(PCH₃R₂)[N(SiMe₂CH₂PPh₂)₂], 4a-4c. Some of the intermediates proposed in the thermolysis of 2a are synthesised independently by the reaction of iridium methylidene complex, Ir=CH₂[N(SiMe₂CH₂PPh₂)₂]. 10, with PHPh₂. The complex fac-Ir(ɳ²-CHPhPMe₂)H[N(SiMe₂CH₂PPh₂)₂] is generated from the reaction of Ir(CH₂Ph)Br[N(SiMe₂CH₂PPh₂)₂] with KPMe₂ without intermediacy of the corresponding phosphide complex. The photolysis of 2a-2c also yields species 4a-4c; however, no intermediacy of the cyclometallated hydride complexes 3a-3c is observed during this transformation. Upon thermolysis of the phenylphosphide complex 2d, only the corresponding iridium(I) phosphine complex, Ir(PHCH3Ph)[N(SiMe2CH2PPh2)2], 4d, is obtained, which is also the photolysis product of 2d. Ir(CH₃)PPh₂[N(SiMe₂CH₂PPh₂)₂], 2a, reacts at -78°C with dimethyl-acetylenedicarboxylate to yield an octahedral iridium(III) complex in which the alkyne has bridged between the phosphide ligand and the phosphine group of the chelating ligand. In addition, one of the phenyl groups from the chelating phosphine has migrated to the metal. On the other hand, Ir(CH₃)PMe₂[N(SiMe₂CH₂PPh₂)₂], 2c, reacts with the same alkyne to yield a product in which the alkyne has bridged between the phosphide group and the iridium centre. The reaction of 2a with diphenylacetylene affords Ir(PhC≡CPh)[N(SiMe₂CH₂PPh₂)₂] and free methyl-diphenylphosphine. Complex 2a reacts with terminal alkynes (RC≡CH; R = H, Ph, ¹Bu) to yield acetylide complexes of formula Ir(CH₃)PHPh₂(C≡CR)[N(SiMe₂CH₂PPh₂)₂]- The methylidene complex, lr=CH₂[N(SiMe₂CH₂PPh₂)₂], 10, prepared by the reaction of Ir(CH₃)I[N(SiMe₂CH₂PPh₂)₂] with KO¹Bu, reacts with phosphines PHR₂ (R = Ph, ¹Bu) to afford the cyclometallated hydride complexes, fac-Ir(ɳ²-CH₂PR₂)H[N(SiMe₂CH₂PPh₂)₂], via a five-coordinate methylidene phosphine intermediate. The reaction of 10 with PH₂Ph yields similar cyclometallated hydride product, but in this case the five-coordinate intermediate is not observed. The methylidene complex 10 reacts with the electrophiles MeI and AlMe₃ to yield Ir(ɳ²-C₂H₄)H(I)[N(SiMe₂CH₂PPh₂)₂] and Ir((µ-AlMe₂)H[N(SiMe₂CH₂PPh₂)₂], respectively. Reaction of 10 with HC≡CH affords an ɳ³˗allyl acetylide complex Ir(ɳ³-C₃H₅)(C≡CH)[N(SiMe₂CH₂PPh₂)₂]. A trimethylenemethane complex, fac-Ir{ɳ⁴-C(CH⁴₂)₃}[N(SiMe₂CH₂PPh₂)₂], is obtained readily upon exposing 10 to 1,2-propadiene. The reaction of 10 with 1,3-butadiene affords a pentenyl product, Ir(σ-ɳ³-C₅H₈)[N(SiMe₂CH₂PPh₂)₂]. In previous studies, the iridium(I) ɳ²-cyclooctene species, Ir(ɳ²-C₈H₁₄)-[N(SiMe₂CH₂PPh₂)₂], 25, has served as a useful starting material in the preparation of a number of iridium(I) and iridium(III) amide complexes. This complex is thermally stable, but upon photolysis, it yields Ir(H)₂[N(SiMe₂CH₂PPh₂)₂] and a mixture (2:1) of free 1,3-and 1,5-cyclooctadiene. This dehydrogenation process proceeds through ɳ³-allyl hydride intermediate, Ir(ɳ³-C₈H₁₃)H[N(SiMe₂CH₂PPh₂)₂]- The cyclo-octene ligand in 25 can be replaced by 1,3-butadiene and. 1,2-propadiene. The products obtained from these reactions are Ir(ɳ⁴-C₄H₆)[N(SiMe₂CH₂PPh₂)₂] and Ir(ɳ²-C₃H₄)[N(SiMe₂CH₂PPh₂)₂]. respectively. The reaction of 25 with AlMe₃ affords Ir(µ-AlMe₂)Me[N(SiMe₂CH₂PPh₂)₂]. / Science, Faculty of / Chemistry, Department of / Graduate

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The complex, IrH₂(PMe₃)₃Cl (1), was previously found to be, not only unexpectedly water-soluble but also an effective homogeneous catatyst for the hydrogenation of unsaturates in water. The results of extensive ³¹P NMR studies on the aqueous system of (1) indicate that (1) is in equilibrium with the iridium(III) dihydrido “aquo” complex, [IrH₂(PMe₃)₃(H₂O)]⁺, and not the μ-chloro bridged complex, { [IrH₂(PMe₃)₃]₂Cl}⁺ (2), as previously reported. The calculated K_eq value for the aqueous equilibrium is (0.0037 ± 0.0003) M. Thermodynamic data (ΔH = 30.8 kJ/mol, ΔS = 56.0 J/(Kmol), and ΔG = 14.1 kJ/mol) obtained from variable temperature ³¹P NMR studies are consistent with the proposed equilibrium system. The complexes IrH₂(PMe₃)₃X (X = O₂CPh (3), I (4), and Br (6) were synthesized and examined. The complexes IrH₂(PMe₃)₃X (X = H₂O and F) could not be isolated. (3) was determined to dissociate completely in water to form the iridium(III) dihydrido “‘aquo” complex, [IrH₂(PMe₃)₃(H₂O)]⁺, seemingly explaining the greater catalytic activity of (3). Solubility of the halo complexes decreased from moderately soluble (1), to slightly soluble (6), to very slightly soluble (4). The solubilities of (4) and (6) were too low to allow quantification of their equilibria. Finally it was observed that linear relationships exist between the electronegativity of the ligand, X, and the ¹H and ³¹P NMR chemical shifts of the hydrides and the phosphines for the complexes, IrH₂(PMe₃)₃X. These relationships are consistent with the findings of Birnbaum. / Ph. D.

Cheung, Chi Wai. / "December 2010." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.