Diiodo Complex Research Articles

Regulating the photoluminescence of aluminium complexes from non-luminescence to room-temperature phosphorescence by tuning the metal substituents

Although luminescent aluminum compounds have been utilized for emitting and electron transporting layers in organic light-emitting diodes, most of them often exhibit not phosphorescence but fluorescence with lower photoluminescent quantum yields in the aggregated state than those in the amorphous state due to concentration quenching. Here we show the synthesis and optical properties of β-diketiminate aluminum complexes, such as crystallization-induced emission (CIE) and room-temperature phosphorescence (RTP), and the substituent effects of the central element. The dihaloaluminum complexes were found to exhibit the CIE property, especially RTP from the diiodo complex, while the dialkyl ones showed almost no emission in both solution and solid states. Theoretical calculations suggested that undesired structural relaxation in the singlet excited state of dialkyl complexes should be suppressed by introducing electronegative halogens instead of alkyl groups. Our findings could provide a molecular design not only for obtaining luminescent complexes but also for achieving triplet-harvesting materials.

Facile Synthesis of Benzimidazole and Benzothiazole Compounds Mediated by a Zinc Precatalyst Supported by an Iminopyrrole‐Morpholine Ligand

AbstractThree zinc complexes, with the general formula {κ2‐C4H3NH[2‐CH=NCH2CH2N(CH2CH2)2O]ZnX2} [X=Cl (2 a), Br (2 b), I (2 c)], supported by a neutral iminopyrrole‐morpholine ligand, were synthesized by the reaction between {C4H3NH‐2‐[CH=NCH2CH2N (CH2CH2)2O]} (1) and anhydrous zinc dihalides (ZnCl2, ZnBr2, ZnI2) at ambient temperature in dry methanol. The zinc complexes were fully characterized using multinuclear NMR spectroscopic techniques and the molecular structures of complexes 2 a and 2 c in their solid states were determined by single‐crystal X‐ray diffraction analysis. The zinc diiodo complex (2 c) proved to be a competent precatalyst in the formation of a wide range of benzimidazole and benzothiazole compounds, via aerobic oxidative condensation of several benzylamines with o‐phenylenediamine, N‐phenyl‐o‐phenylene‐diamine, and o‐mercaptoaniline. The benzimidazole and benzothiazole derivatives were successfully characterized using 1H and 13C{1H} NMR spectroscopy.

Seven‐Coordinate MoII−Diiodo Complexes with Benzothiazole−N‐Heterocyclic‐Carbene Ligands and Their Mo0 Precursors: Synthesis, Structures, and Catalytic Application in the Epoxidation of cis‐Cyclooctene

AbstractThe oxidative addition of I2 to molybdenum(0) complexes [Mo(CO)4(LNC)] (1–3; LNC1=1‐(benzothiazolin‐2‐yl)‐3‐allyl‐2‐ylidene; LNC2=1‐(benzothiazolin‐2‐yl)‐3‐benzylimidazol‐2‐ylidene; LNC3=1‐(benzothiazolin‐2‐yl)‐3‐methylimidazol‐2‐ylidene) afforded the first isolable and crystallographically elucidated seven‐coordinate MoII−diiodo complexes, [Mo(CO)3I2(LNC)] (4–6), with N‐heterocyclic carbene (NHC) ligands. The application of complexes 1–6 as precatalysts for the epoxidation of cis‐cyclooctene with tert‐butyl hydroperoxide (TBHP) as an oxidant has also been studied. Complexes 1–3 performed better than previously reported Mo0−carbonyl−NHC complexes, thereby producing the epoxide in 80–90 % yield after 24 h. Complexes 4–6 were superior to complexes 1–3. Complex 5 was the most‐active MoII−NHC complex, thereby achieving the epoxide in quantitative yield after 6 h.

Closely Related Benzylene-Linked Diamidophosphine Scaffolds and Their Zirconium and Hafnium Complexes: How Small Changes of the Ligand Result in Different Complex Stabilities and Reactivities

The closely related benzylene-linked diaminophosphines PhP(CH2C6H4-o-NHPh)2 ([PhA]H2) and PhP(C6H4-o-CH2NHXyl)2 ([B]H2) were prepared as robust alternatives to the previously reported N,N′-bis(trimethylsilyl)-substituted derivative PhP(CH2C6H4-o-NHSiMe3)2 ([SiA]H2). Upon reaction of [PhA]H2 and [B]H2 with M(NMe2)4 (M = Zr, Hf), the respective dimethylamido complexes [PhA]M(NMe2)2 and [B]M(NMe2)2 ([PhA]-1-M and [B]-1-M, M = Zr, Hf) were isolated in high yields and converted to the corresponding diiodo derivatives [PhA]MI2 and [B]MI2 ([PhA]-2-M and [B]-2-M, M = Zr, Hf). In contrast to [SiA]ZrI2, these thermally robust diiodo complexes were found to react cleanly with Bn2MgL2 (L = THF or Et2O), resulting in the corresponding dibenzyl species [PhA]MBn2 and [B]MBn2 ([PhA]-4-M and [B]-4-M, M = Zr, Hf). Upon addition of [B]H2 to [B]ZrBn2, the related homoleptic species [B]2Zr ([B]-5-Zr) was generated. Similar 2:1 complexes have not been observed for the hafnium homologue bearing the latter ligand or for [SiA]- o...

Hydrodealkoxylation reactions of silyl ligands at platinum: reactivity of SiH₃ and SiH₂Me complexes.

The platinum(ii) complex [Pt(H)2(dcpe)] (; dcpe = 1,2-bis(dicyclohexylphosphino)ethane) reacts with an excess of the dialkoxymethylsilanes (HSiMe(OR)2; R = Me, Et) to give the bis(silyl) complex [Pt(SiH2Me)2(dcpe)] () and trialkoxymethylsilanes by hydrodealkoxylation reactions. These rearrangements of the silyl ligands involve Si-O bond activations. The exchange of the alkoxy moieties against silicon-bound hydrogen atoms occurs stepwise. The intermediate complexes [Pt(H){SiMe(OEt)2}(dcpe)] (), [Pt{SiMe(OEt)2}2(dcpe)] (), [Pt{SiHMe(OEt)}2(dcpe)] () and [Pt{SiHMe(OMe)}2(dcpe)] () were detected. Treatment of the complex with an excess of dichloromethylsilane yields the bis(silyl) complex [Pt(SiMeCl2)2(dcpe)] (). The hydrido silyl complex [Pt(H)(SiMeCl2)(dcpe)] () was identified as an intermediate. The reactions of the complexes [Pt(SiH3)2(dcpe)] () and [Pt(SiH2Me)2(dcpe)] () with iodomethane lead to a transfer of the SiH3 and SiH2Me ligands. Methylsilane and dimethylsilane, respectively, as well as the platinum diiodo complex [Pt(I)2(dcpe)] () were identified as main products.

A mild and efficient method for the synthesis of structurally diverse 1,2,3-triazolylidene palladium(II) diiodo complexes. Comparison of catalytic activities for Suzuki–Miyaura coupling

Synthesis of mononuclear and PEPPSI type palladium diiodo complexes of 1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene without the use of strong bases and silver salts and at ambient conditions using Pd(OAc)2 is reported. Using stoichiometric amounts of bidendate ligands such as pyrazine, 4,4′-bipyridine and DABCO bridged binuclear palladium diiodo complexes were obtained in excellent yields. By simple variation of reagents and their stoichiometry, one can control the reactions towards the selective formation of mononuclear [(Tz)2Pd(I)2] complexes, iodo bridged binuclear complexes [(Tz)Pd(I)(μ-I)2Pd(I)(Tz)], mononuclear PEPPSI type complexes [(Tz)Pd(I)2(Py)], bridged binuclear PEPPSI type complexes [(Tz)Pd(I)2-(bridge biPy)-(I)2Pd(Tz)]. The catalytic activities of these three structurally different types of complexes are compared for Suzuki–Miyaura coupling reaction.

Synthesis of Au(I) Trifluoromethyl Complexes. Oxidation to Au(III) and Reductive Elimination of Halotrifluoromethanes

Au(I) trifluoromethyl complexes [Au(CF3)L] (L = N-heterocyclic carbene (NHC), isonitrile, phosphine, P(OMe)3) and [Au2(CF3)2(μ-dppe)] are prepared by reaction of [Au(X)L] (X = Cl, I) or [Au2Cl2(μ-dppe)], respectively, with AgF and Me3SiCF3. The analogous reaction of PPN[Au(C6F5)Cl] (PPN+ = [Ph3PNPPh3]+) gives a mixture of complexes of the type PPN[Au(CF3)x(C6F5)2–x] (x = 0, 1, 2). Single crystals of the new complex PPN[Au(CF3)(C6F5)] are obtained by liquid diffusion from this mixture, and its crystal structure was determined by X-ray diffraction. Acyclic diaminocarbene complexes [Au(CF3){C(NEt2)(NHR)}] (R = tBu, 2,6-dimethylphenyl) are obtained by reaction of [Au(CF3)(CNR)] with NHEt2. Oxidation of the NHC complex [Au(CF3)(IPr)] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with PhICl2, Br2, I2 or ICl affords [Au(CF3)(X)(Y)(IPr)] (X = Y = Cl, Br I; X = Cl, Y = I). The dicloro, dibromo, and chloro(iodo) complexes are stable in solution in the dark. In contrast, the diiodo complex is unstable and decomposes to [AuI(IPr)] and ICF3. Under photoirradiation, complexes [Au(CF3)(X)(Y)(IPr)] undergo reductive elimination to give YCF3 and [AuX(IPr)] (X = Y = Cl, Br; X = Cl, Y = I).

Asymmetric synthesis of a chiral diarsine ligand via a cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and diphenylvinylarsine

The organopalladium complex containing ortho-metallated (S)-[1-(dimethylamino)ethyl]naphthalene as a chiral auxiliary has been successfully employed to promote the asymmetric cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and diphenylvinylarsine. In the intramolecular cycloaddition reaction, a pair of separable diastereomeric palladium complexes was obtained in the ratio of 6:1. The chiral naphthylamine auxiliary could be removed chemoselectively from the template by treatment with HCl and subsequently NaI to generate the neutral diiodo complex [(As–As)PdI2]. Treatment of the diiodo complex with KCN gave the enantiomerically pure As–As bidentate ligand in quantitative yield. In contrast to the reported similar P–P and As–P analogues, both arsenic donors in the diiodo complex could be readily eliminated to produce a structurally novel dimetallic complex.

Synthesis and characterization of a series of rhodium, iridium, and ruthenium isocyanide complexes

Several new electrophilic metal isocyanide complexes have been fully characterized and reported herein. Isocyanide induced cleavage of the dimer, [LMCl2]2 {LM=Cp∗Ir, Cp∗Rh, or (p-cymene)Ru}, with 2,6-xylylisocyanide or 2,6-diethylphenylisocyanide produces complexes of the general formula LM(CNAr)Cl2. Halide metathesis of the dichloro complexes with sodium iodide produces the corresponding complexes with the general formula LM(CNAr)I2. For the analogous ruthenium complexes better results were achieved via isocyanide induced cleavage of [(p-cymene)RuI2]2 and was synthesized differently from previous reports. Several neutral complexes in reaction with AgPF6 in acetonitrile form cationic, solvent-coordinated complexes have been fully characterized. Most reactions with rhodium decomposed to either [Cp∗RhCl(MeCN)]2[(PF6)2] starting from the dichloro complexes, or [Cp∗Rh(MeCN)3,(PF6)2] and Cp∗Rh(CNAr)I2 starting from the diiodo complexes. Several bases were probed to see if cyclization could be induced, but were not successful in any case. Many of these complexes have been characterized by single crystal X-ray crystallography.

Zirconium Hydrazides as Metallanitrene Synthons: Release of Molecular N2 from a Hydrazinediido Complex Induced by Oxidative N–N Bond Cleavage

The N–N bond in the zirconium hydrazinediido(2−) complex [Zr(N2TBSNpy)(NNPh2)(py)] (1) is readily cleaved by one-electron oxidation. Reacting [Zr(N2TBSNpy)(NNPh2)(py)] (1) with 0.5 molar equiv of iodine led to the release of molecular N2 and yielded the mixed diphenylamido/iodo complex [Zr(N2TBSNpyNPh2)(I)] (2). Exposure of hydrazinediide 1 to an excess of iodine resulted in further oxidation of the diphenylamido ligand, yielding the diiodo complex 3 and tetraphenylhydrazine. Similar reactivity was observed in the reaction of 1 with diphenyl diselenide and diaryl disulfides, which reacted to give the corresponding diphenylamido/arylchalcogenido complexes [Zr(N2TBSNpyNPh2)(SePh)] (4a) and [Zr(N2TBSNpy)(NPh2)(SAr)] (Ar = Ph (4b), C6F5 (4c)) along with N2. The reactions were also carried out on an NMR scale with a 15Nα-labeled hydrazido complex (1-15N). In all cases a single 15N NMR resonance at 310.16 ppm, assigned to 15N2, indicated the formation of dinitrogen from the Nα atom in the hydrazide. A crossover labeling experiment employing a 1:1 mixture of 1 and 15Nα-labeled 1-15N revealed that the isotope distribution is, as expected, statistical 1:2:1 (14N2: 14/15N2: 15N2), which is consistent with a reaction pathway involving a dinuclear intermediate in the dinitrogen-forming step. Complex 1 reacted with N2O to give a mixture of two compounds, the bis(diphenylamido) complex 6 and the doubly bridged μ-oxo complex 7. In contrast, reaction of 1 with 1 molar equiv of pyridinium N-oxide only gave the doubly bridged μ-oxo complex 7 along with 2,2′-bipyridine and diphenylamine.

Template effects on the asymmetric cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and diphenylvinylphosphine and their arsenic elimination reaction

Abstract The organopalladium complex containing ortho-metalated (S)-[1-(dimethylamino)ethyl]naphthalene as the chiral template was employed to promote the asymmetric cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and diphenylvinylphosphine. It has been proven that the chiral template incorporating napthylamine is more efficient than the benzylamine based analogue as evidenced by the drastic improvement in stereoselectivity and reaction rate. However, when no chiral template was employed, trans-[PdI2(3,4-dimethyl-1-phenylarsole)2] reacted with trans-[PdI2(diphenylvinylphosphine)2] producing a structurally novel diiodo complex, as a result of an interesting selective cleavage of one As–C bond in the norbornene skeleton and subsequent rearrangements within the skeletal framework. The molecular structure of the diiodo product has been confirmed by X-ray crystallography. Structural analysis showed that in addition to the normal As–P five-membered ring, there is one new five-membered ring containing As–O bond being formed during the course of the reaction along with another seven-membered ring incorporating a hydroxy group.

Platinum(IV) Metallacrown Ethers: Synthesis, Structures, Host Properties and Anticancer Evaluation

Platinum(IV) metallacrown ethers [PtBr2Me2{im(CH2CH2O)xCH2CH2im}] (im = imidazol-1-yl; x = 2−5, 7; 3−7) and [PtBr2Me2{bim(CH2CH2O)xCH2CH2bim}] (bim = benzimidazol-1-yl; x = 1, 2, 5, 7; 9−12) were synthesized via the reaction of [(PtBr2Me2)n] with the appropriate α,ω-bis(imidazol-1-yl) or α,ω-bis(benzimidazol-1-yl) polyether. Reactions with 1,2-bis(imidazol-1-yl)ethane, bis(2-(imidazol-1-yl)ethyl) ether, or 1,2-bis(benzimidazol-1-yl)ethane yielded the dinuclear complexes [(PtBr2Me2)2{μ-im(CH2CH2O)xCH2CH2im}2] (x = 0, 1; 1, 2) and [(PtBr2Me2)2{μ-bimCH2CH2bim}2] (8), respectively. In addition, the diiodo complex [PtI2Me2{im(CH2CH2O)2CH2CH2im}] (13) was prepared from the reaction of [PtMe2(cod)] with I2 in the presence of im(CH2CH2O)2CH2CH2im. Characterization by microanalysis and NMR spectroscopy, as well as X-ray crystal structure analysis of several of the metallacrown ethers (3, 5, 9 and 10) and dinuclear complexes (2 and 8), is described. The ability of the larger metallacrown ethers (5−7, 11 and 12) to ...

Asymmetric synthesis of a chiral hetero-bidentate As–P ligand containing both As and P-stereogenic centres

The organopalladium complex containing ortho-metalated ( S)-[1-(dimethylamino)ethyl]naphthalene as the chiral auxiliary has been used as the chiral template to promote the asymmetric cycloaddition reaction between phenyldivinylphosphine and 3,4-dimethyl-1-phenylarsole. The reaction was completed in 1 h at room temperature, with the formation of two isomeric cycloadducts in the ratio 1:3. The major phenylvinylphosphino-substituted asymmetrical hetero-bidentate arsanorbornene ligand with chirality residing on both As and P centers was obtained stereoselectively on the chiral palladium template in moderate yield. The chiral heterobidentate ligand was isolated in its enantiomerically pure form by removal of the chiral auxiliary using concentrated hydrochloric acid and subsequent cleavage from the neutral complex [(As–P)PdCl 2] by using potassium cyanide. Similar to the earlier reported analogous diphenylphosphino-substituted asymmetrical heterobidentate arsanorbornene (As–P) ligand, an arsenic elimination process was also found in the dichloro and dibromo palladium complex whereas the diiodo species did not show similar reactivity, but the corresponding η 2 diiodo complex could be obtained from the η 2 dibromo complex by treatment with sodium iodide.

Synthesis, DNA interaction and cytotoxicity studies of cis-{[1, 2-bis(aminomethyl)cyclohexane]dihalo}platinum(II) complexes

A series of platinum compounds with an analogue structure to cisplatin have been synthesized and their biological activity against HL-60 cancer cell line has been studied. The interaction with DNA was evaluated by circular dichroism (CD), electrophoresis and atomic force microscopy (AFM) techniques showing slight but significant structure-dependent differences among the evaluated complexes. The cytotoxicity assays afforded interesting relationships between the structure and the biological activity, thus, a better antiproliferative activity was observed for the complexes with higher hydrophobicity: the methoxylated complexes showed better activity than the hydroxylated ones (17versus20 and 19versus21). Especially compound 22 having a fatty acid subunit presented a promising cytotoxic activity. On the other hand, dichloro complexes 12 and 13 had better activities than the diiodo complexes, probably due to their better metabolic stability. Between both dichloro complexes the aromatic one showed much higher activity, which could be rationalized on the basis of the intercalating ability of the benzene ring. The flow cytometry assays indicated that most of the complexes induced the cell death by apoptosis except for aromatic compound 12 and the lipophilic compound 22 that induced preferably a mechanism of necrosis.

Preparation and Characterization of Half-Sandwich Cobalt(III) Complexes of Cp Ligands with a Rigid Thioanisole Side-Chain

New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2(thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (35) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)4·2Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1 H, 13 C and 19 F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.

Synthesis and Antimicrobial Activities of Isomers of N(4),N(11)-Dimethyl-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane and Their Nickel(II) Complexes

The reactions of two isomers of 3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (differing in the orientation of the methyl groups on the chiral carbon atoms), designated as L(B) and L(C), with CH(3)I in the ratio of 1:4 resulted in the substitution of the N(4) and N(11) protons by CH(3) groups, forming the dimethyl derivatives L(BZ) and L(CZ), respectively. These ligands, on interaction with nickel(II) acetate tetrahydrate and subsequent addition of lithium perchlorate, produce square-planar yellow [NiL(BZ)][ClO(4)](2) and orange [NiL(C'Z)][ClO(4)](2). These nickel complexes undergo axial ligand addition reactions with NCS(-), Cl(-), Br(-), and I(-) as X(-) to form six-coordinate trans-diisothiocyanato, -dichloro, -dibromo, and -diiodo complexes of formula [NiLX(2)], where L = L(BZ) or L(C'Z), and X = SCN, Cl, Br, or I. All these compounds have been characterized on the basis of analytical, spectroscopic, conductometric, and magnetochemical data. The structures of L(BZ) and two variants of [Ni"L(BZ)"][ClO(4)](2) (crystallizing in the space group P2(1)/n and Pn, respectively; "L(BZ)" symbolizes partially methylated ligand) have been determined by single-crystal X-ray analyses. The antifungal and antibacterial activities of these compounds have been studied against some phytopathogenic fungi and bacteria.

Transfer of heterocyclic carbene ligands from chromium to gold, palladium and platinum

The reaction of pentacarbonyl(pyrazolin-3-ylidene)chromium complexes, ▪ ( 2a– c) (R = Ph ( a), C 6H 4NMe 2-4 ( b); (C 5H 4)FeCp ( c)), with [AuCl(SMe 2)], H[AuCl 4], [PdCl 2(NCPh) 2] and [PtCl 2(NCPh) 2] gives, by transfer of the heterocyclic carbene ligand, new chloro pyrazolin-3-ylidene complexes of gold(I) and gold(III), dichloro bis(pyrazolin-3-ylidene) palladium and dichloro bis(pyrazolin-3-ylidene) platinum in high yield. The chloride ligand in ▪ (Fc = (C 5H 4)FeCp) is readily displaced by trifluoroacetate. The analogous substitution of iodide for the chloride ligands in ▪ (M = Pd, Pt) give the corresponding diiodo complexes although in a much slower reaction. In contrast, the reaction of silver trifluoroacetate with ▪ affords a binuclear Pd–Ag complex containing two pyrazolin-3-ylidene and three trifluoroacetate ligands two of whom occupy bridging positions between Pd and Ag. The reactions of the pyrazolidin-3-ylidene complex ▪ (R = C 6H 4NMe 2-4) with [AuCl(SMe 2)] and [PdCl 2(NCPh) 2] yield chloro pyrazolidin-3-ylidene gold and dichloro bis(pyrazolidin-3-ylidene) palladium complexes. The related dichloro bis(tetrahydropyrimidin-4-ylidene) palladium complex is formed in the reaction of ▪ with the palladium complex [PdCl 2(NCPh) 2]. The solid-state structures of several of these heterocyclic carbene complexes including the structure of the binuclear Pd–Ag complex are established by X-ray structure analyses.

Sulfur-Bonded 2-Methylthiopyridine (2-MeSpy) Complex of Iridium(III). Crystal Structure of [Cp*IrI2(2-MeSpy-κS)] (Cp* = η5-C5Me5)

Abstract 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 3 exhibited a dissociation equilibrium of 2-MeSpy similar to the corresponding thioanisole complex of [Cp*IrI2(MeSPh)].

Multinuclear NMR study and crystal structures of complexes of the types cis- and trans-Pt(amine) 2I 2

Complexes of the types cis- and trans-Pt(amine) 2I 2 were studied by spectroscopic methods, especially by multinuclear NMR spectroscopy. In 195Pt NMR, the cis diiodo compounds with primary amines were observed between −3342 and −3357 ppm in acetone, while the trans compounds were found between −3336 and −3372 ppm. For the secondary amines, the chemical shifts were observed at lower fields. In 1H NMR, the trans complexes were observed at higher fields than the cis compounds, while in 13C NMR, the reverse was observed. The 2 J( 195Pt– 1H) and 3 J( 195Pt– 1H) coupling constants are larger for the cis compounds (ave. 67 and 45 Hz, respectively) than for the trans isomers (ave. 59 and 38 Hz). In 13C NMR, the values of 2 J( 195Pt– 13C) and 3 J( 195Pt– 13C) were also found to be larger for the cis complexes (ave. 17 and 39 Hz versus 11 and 28 Hz). There seems to be a slight dependence of the p K a values of the protonated amines or the proton affinity in the gas phase with the δ(Pt) chemical shifts. The crystal structures of eight diiodo complexes were determined. These compounds are cis-Pt(CH 3NH 2) 2I 2, cis-Pt(n-C 4H 9NH 2) 2I 2, cis-Pt(Et 2NH) 2I 2, trans-Pt(n-C 3H 7NH 2) 2I 2, trans-Pt( iso-C 3H 7NH 2) 2I 2, trans-Pt(n-C 4H 9NH 2) 2I 2, trans-Pt(t-C 4H 9NH 2) 2I 2 and trans-Pt(Me 2NH) 2I 2. The Pt–N bond distances located in trans position to the iodo ligands were compared to those located in trans position to the amines. The Pt–N bond in cis-Pt(Et 2NH) 2I 2 are much longer than the others, probably caused by the steric hindrance of the two very bulky ligands located in cis positions.

Mono(sulfido)-bridged mixed-valence nitrosyl complex: protonation and oxidative addition of iodine across the Ir(II)-Ir(0) bond.

Treatment of [Cp*IrH(SH)(PMe3)] (Cp* = eta5-C5Me5) with [IrCl2(NO)(PPh3)2] in the presence of triethylamine yielded the sulfido-bridged Ir(II)Ir0 complex [Cp*Ir(PMe3)(mu-S)Ir(NO)(PPh3)], which further reacted with I2 and triflic acid to give the diiodo complex [Cp*Ir(PMe3)(mu-I)(mu-S)IrI(NO)(PPh3)] and the hydrido complex [Cp*Ir(PMe3)(mu-H)(mu-S)Ir(NO)(PPh3)][OSO2CF3], respectively.