Isonitrile Complexes Research Articles

Liquid-crystalline gold–isonitrile complexes

Gold–isonitrile complexes as a new family of metallomesogens are prepared and even non-mesomorphic isonitiles have been found to form liquid crystals when coordinated to an AuICl moiety.

Synthesis of [amine(tert-butylisonitrile) dihydroboron(III)] cations via the antimony pentachloride complexes of amine-dihydrocyanoboranes. A new route to amine-carboxyboranes

The reaction of the cyanoborane complexes L·BH 2CN [where L = R 3N (R = Me, Et, Pr, Bu); quinuclidine (Q) and Ph 3P] with SbCl 5 in CCl 4 afforded 1:1 complexes. Coordination of antimony to the nitrogen atom of the cyano groupp was clearly implied by the 35–42 cm −1 shift of the ν CN cyano resonances towards the higher wave-numbers. The L·BH 2CN·SbCl 5 complexes, carrying a bridge-head CN function, readily transformed with Bu t Cl into the [BH 2(L)CNBu t ]SbCl 6 tert-butylnitrilium salts with high crystallization ability. In the case of L = R 3N and Q substituents partial chlorination of the BH bond accompanied the formation of the nitrilium salt. The relatively weak coordination of the Bu t NC ligand in the above antimony complexes was indicated by the 2282–2292 cm −1 values observed for ν CN, unexpectedly high for isonitrile complexes, as well as by the exchange reactions with strong donors (i.e. Me 2SO, Q, DMAP), giving rise to the liberation of the Bu t NC. The synthetic utility of related complexes was shown by the highly efficient transformation of [BH 2(L)CNBu t ]SbCl 6 into Me·BH 2C(O)NHBu t in an alkaline medium, whose acid hydrolysis furnishes Me 3N·BH 2COOH, a well-known and important compound in boron chemistry with high yield. Preparation of this substance with the presented new process, via the tert-butylnitrilium salt, is much more efficient than by means of the previously reported procedures employing the ethylnitrilium salt. The proposed structures of the new compounds L·BH 2CN·SbCl 5, [BH 2(L)CNBu t ]SbCl 6 and Me 3·BH 2C(O)NHBu t were derived from IR, 1H and 11B NMR spectral data.

Liquid-crystalline palladium– and platinum–isonitrile complexes: synthesis, mesomorphic properties and molecular structure

Three series of mesogenic isonitrile derivatives and their platinum(II)(4–6) and palladium(II)(7–9) complexes have been synthesized as a new family of liquid-crystalline materials. The isonitriles themselves exhibit both nematic and smectic mesophases accompanied by considerable decomposition due to their thermal instability. The coordination of the isonitriles to a metal results in a large increase in their thermal stability, and the platinum and palladium complexes show mesomorphic properties in a high and broad temperature range without any decomposition except a few palladium complexes. The liquid-crystalline complex Ptl2(CNC6H4C6H4OC7H15)2(6, X = I, n= 7) has been crystallographically characterised and the relationships between structure and property of the metal–isonitrile complexes are discussed.

Homogeneous Catalysis with Dicationic PdII Complexes: Aldol reaction of methyl isocyanoacetate with benzaldehyde

AbstractA series of dicationic PdII‐acetonitrile complexes containing bi‐ and tridentate nitrogen and bidentate phosphine ligands (some of which are chiral) has been prepared as their BF4 salts. The molecular structures for two of these, [Pd(CH3CN)2(bipy)] (BF4)2 (4) and [Pd(CH3CN)((pybox)(i‐Pr))] (BF4)2((S,S)‐pybox(i‐Pr) = 2,6‐bis[(S)‐4′‐isopropyloxazolin‐2′‐yl]pyridine, 5) have been determined by X‐ray diffraction. All of these complexes are shown to be effective homogeneous catalysts for the aldol‐type condensation of the isonitrile, methyl isocyanoacetate, with benzaldehyde. Two isonitrile complexes, [Pd(2,2′‐bipyridyl)(CNCH2COOCH3)2] (BF4)2 and [Pd((S,S)‐pybox(i‐Pr))(CNCH2COOCH3)] (BF4)2, have also been prepared.

Radiopharmacological studies of 99mTc-CPI: Experience with isolated rat atrial tissue

Extraction, washout and chemical integrity of technetium(I) hexakis (2-carbomethoxy-2-isocyano propane), ( 99mTc-CPI) were evaluated in isolated contractile rat atrial tissue. 99mTc-CPI accumulated linearly over time at 32 °C with uptakes that were both concentration dependent and temperature sensitive. Uptake rates also increased with contractile strength, indicating a dependence of retention on metabolic status of the tissue. Retention indices showed that percent washout of 99mTc-CPI was much slower than control studies with 99mTcO 4. HPLC analysis of retained radioactive products in atrial tissue showed most of the activity present as the 99mTc-CPI complex (75%). These observations in isolated rat atrial tissue help explain the interspecies differences in biodistribution of 99mTc-CPI and support the membrane potential dependent model for uptake and retention of technetium isonitrile complexes.

Molybdenum-95 nuclear magnetic resonance studies on molybdenum carbonyl complexes of isonitriles and amines

The 95Mo NMR spectra of 28 molybdenum carbonyl complexes of isonitriles and amines are reported. Within similar classes of complexes excellent correlation is found between 95Mo chemical shifts and ligand π-acceptor ability and, more importantly, complex structures. Application to the analysis of diastereomeric complexes is reported. From analysis of linewidths and relaxation behavior, the surprising result is found that 95Mo linewidths in isonitrile complexes are not due to coupling to the electric field gradient, but to scalar coupling between the 95Mo and 14N nuclei which, in turn, is inversely proportional to the substitution number n in complexes MO(CO) 6- n (CNR) n . A dependence of chemical shift on temperature of 0.3 ppm/°C is found for MO(CO) 6.

Übergangsmetall-Silyl-Komplexe: XXXVIII. Darstellung Phosphan-substituierter Hydrido-Silyl-Komplexe des Chrom, Molybdän und Wolfram, (CO) 5- n(R′ 3P) nM(H)SiR 3 ( n = 2, 3) und Bildung der Hydrido-Chloro-Komplexe (CO) 3(L–L)M(H)Cl durch Umsetzung von (CO) 3(L-L)M(NCR′) mit HSiClR 2 [L-L = tmeda, bipy, dppe, (PPH 3) 2

At least two phosphorus atoms at the metal ( n⪖2) are necessary to obtain stable hydrido-silyl complexes of the type (CO) 5- n (R′ 3P) n M(H)SiR 3 (M = Cr, Mo, W). The complexes (CO) 3(dppe)M(H)SiR 3 and (CO) 2(tdppme)M(H)SiR 3 are obtained either by photochemical reaction of (CO) 4(dppe)M or (CO) 3(tdppme)M, or by thermal reaction of (CO) 4(dppe)M(THF) with silanes HSiR 3. Reaction of the isonitrile complexes (CO) 3(L-L)M(NCR′) (M = Mo, W; L–L = tmeda, bipy, dppe, (PPH 3) 2) with silanes HSiR 2Cl does not yield hydrido-silyl complexes, but instead the hydrido-chloro complexes (CO) 3(L-L)M(H)Cl. The latter complexes were also prepared by reaction of (CO) 3(L–L)M(NCR′) with HCl for comparison. The molecular structure of (CO) 3(dppe)W(H)Cl was determined by an X-ray structure analysis. The complexes has a capped-octahedral geometry with a facial arrangement of the three CO ligands and the hydride ligand above the triangular face formed by the two phosphorus atoms and a CO ligand.

Alken‐, Alkin‐, Isonitril‐ und Carbonyl‐Komplexe von Kupfer(I) und Silber(1) mit dreizähnigen Sauerstoff‐Chelatliganden

Alkene, Alkyne, Isonitrile, and Carbonyl Complexes of Copper(I) and Silver(I) with Tris‐Chelating Oxygen LigandsThe preparation of η2‐alkynecopper(I) complexes of the composition [LRCu(η2‐alkyne)], alkyne = tolan, dimethyl acetylenedicarboxylate, is described. LR are anionic tris‐chelating oxygen ligands of the type [(C5H5)Co{P(O)R2}3]−, R  OMe, OEt, O‐i‐Pr. The isonitrile complexes [LRM(CNt‐Bu)], M  Cu, Ag, have been prepared from [LOMeCu(CO)] and [{AgLOEt}2], respectively, The silver carbonyl complex [LOEt}Ag(CO)] [v(CO)  2147 cm−1] forms in hexane and methanol solutions of [{AgLOEt}2] under 1 atm of CO gas. The olefin complexes [LRCu(ba)], ba = benzytlideneacetone, have been prepared from [Cu(CH3CN)4]PF6, NaLOMe, and ba and from the carbonyl complex [LOEtCu(CO)] and ba. The coordination of the carbon‐carbon double bond of ba at the LRCu fragment does not lead to a 1,4‐addition of methyllithium to the α,β‐unsaturated ketone.

Cyclopentadienyl-substituierte isonitril-komplexe des vierwertigen molybdäns; synthese und struktur

A large scale, high yield synthesis of the first cyclopentadienyl substituted isonitrile complexes of Mo IV has been developed. The synthetic procedure begins with the quantitative conversion of CpMo(CO) 3I (I) with t-BuNC in CH 2Cl 2 into an isomer mixture of cis and trans CpMo(CO) 2(t-BuNC)I (IIa, IIb). The isomers IIa and IIb, which can be separated by column chromatography on silica, are then oxidatively decarbonylated with iodine to CpMo(CO)(t-BuNC)(I) 3 (III). The reaction of III with two equivalents of t-BuNC in refluxing CH 2Cl 2 gives a mixture of the mono- and dicationic Mo IV complexes [CpMo(t-BuNC) 3(I) 2]I (IV) and [CpMo(t-BuNC) 4I](I) 2 (V). When compound III is reacted with three equivalents of t-BuNC in refluxing CH 2Cl 2 or THF compound V is formed quantitatively. IV also reacts with t-BuNC in CH 2Cl 2 or THF to give exclusively V. Compounds IV and V have been converted with AgBF 4 in acetone into the corresponding BF 4-salts [CpMo(t-BuNC) 3(I) 2]BF 4 (VI) and [CpMo(t-BuNC) 4I](BF 4) 2) (VII). The composition and structure of the new complexes III–VII has been determined by elemental analyses, and IR, from their 1H NMR, 13C NMR, and mass spectra. A comparison of the conductivity data of IV–VII with NR 4 +X − salts (R = alkyl; X = PF 6, Br, I) in 1,2-dichloroethane confirms the ionic nature of IV–VII. An X-ray crystallographic study of V has been carried out. The compound crystallizes in the monoclinic space group P2 1/ c. The unit cell with a 1272(1), b 1361(2), c 2798(3) pm and β 104.18(3)° contains four molecules of V and twelve of CH 2Cl 2. Alternating layers of CH 2Cl 2 molecules and Mo IV dications are observed. The positive charge of the dications is compensated by the two surrounding non-coordinated iodide anions. The dications have a distorted octahedral coordination geometry with a trans arrangement of the pentahapto-bonded Cp and the iodide ligand. The four isonitrile ligands are bent out of the equatorial plane towards the iodide ligand, probably because of steric interactions with the Cp ligand.

Isonitril-substituierte Halbsandwich-Komplexe von Wolfram(IV) / Isonitrile Substituted Half Sandwich Complexes of Wolfram(IV)

A good entry to cyclopentadienyl substituted isonitrile complexes of W(IV) is provided by CpW(CO)(t-BuNC)(I)3 (4), prepared by oxidative decarbonylation of cis- or trans-CpW(CO)2(t-BuNC)I (2,3) with elemental iodine. The isomers 2 and 3, separable by column chromatography on silica at low temperature, are easily obtained from CpW(CO)3I (1) and t-BuNC using Me3NO as a decarbonylating agent. Compound 4 reacts with t-BuNC to yield a mixture of the cationic complexes [CpW(CO)(t-BuNC)2(I)2]I (5) and [CpW(t-BuNC)3(I)2]I (6). The neutral cyano complex CpW(CN)(t-BuNC)2(I)2 (7), resulting from the dealkylation of one tert-butylisonitrile ligand, is also obtained. The insoluble main product 5 is easily separated from 6 and 7, and is converted with AgBF4 to the corresponding BF4-salt [CpW(CO)(t-BuNC)2(I)2]BF4 (8). The soluble byproducts 6 and 7 have been purified by column chromatography on silica. The composition and structure of the new complexes 4-8 have been derived from elemental analyses and spectroscopic investigations. The ionic nature of 6 and 8 has been confirmed by comparison of their conductivity data in 1,2 dichloroethane with that of NR4 +X- salts (R = alkyl; X = Br, I)

Some new cyano and isonitrile complexes of Mo(η5-C5H5)2

Abstract New cyano and isonitrile complexes of molybdenocene, [MoCp2(CN)X] (X = CN, H, Cl), [MoCp2(CNCH3)X]I (X = H, I, CH3), [MoCp2(CNCH3)2]I2 and [MoCp2(CNCH3)], were prepared and characterized. The molybdenocene adduct, [MoCp2(CNCH3)], was prepared by reduction of [MoCp2Cl2] with Na/Hg or from [MoCp2(CNCH3)H]I with NaH. The other complexes were obtained from reaction of [MoCp2IX] (X = H, I) with the appropriate ligand.

Oxygen atom transfer among rhenium, sulfur, and phosphorus. Characterization and reactivity of Re(O)Cl3(Me2S)(OPPh3) and Re(O)Cl3(CNCMe3)2

Re(O)Cl/sub 3/(PPh/sub 3/)/sub 2/ (I) reacts with Me/sub 2/SO to form OPPh/sub 3/ and Re(O)Cl/sub 3/(Me/sub 2/S)(OPPh/sub 3/) (II), not Re(O)Cl/sub 3/(Me/sub 2/SO)(PPh/sub 3/) as had been previously reported. Compounds I and II are catalysts for oxygen atom transfer from Me/sub 2/SO to PPh/sub 3/. The mechanism of these oxygen atom transfer reactions has been studied with oxygen-18 labeling experiments. The rhenium oxo group does not appear to be involved; rather, the rhenium center acts as a Lewis acid activator for a Me/sub 2/SO ligand. The rhenium oxo group does, however, exchange oxygen atoms with Me/sub 2/S/sup 18/O, probably by a similar mechanism. Compound II is an excellent starting material for compounds of the form Re(O)Cl/sub 3/L/sub 2/, with L = isonitriles, phosphines, bipyridine, etc. The compounds Re(O)Cl/sub 3/-(CNR)/sub 2/ (R = CMe/sub 3/ (IV), CHMe/sub 2/, C/sub 6/H/sub 11/) are rare examples of high-valent isonitrile complexes. Data from an X-ray crystal structure of IV are reported. 36 references, 2 figures, 3 tables.

Siliciumhaltige carben-komplexe: VIII. HSiR 3-eliminierung aus carben-komplexen des typs (CO) 5MC(NHR′)SiR 3 (M = Cr, Mo, W)

Upon heating solid monoalkylamino(silyl)carbene complexes (CO) 5MC(NHR′)SiR 3 (M = W: SiR 3 = SiPh 3, R′ = Me, Et, Bu n, C 6H 11, Ph; SiR 3 = SiMePh 2, R′ = Me, Et. M = Mo, Cr: R = Ph, R′ = Me, Et) beyond their melting points, HSiR 3 elimination with formation of the isonitrile complexes (CO) 5MNCR′ and (CO) 4M(CNR′) 2 and (CO) 6M takes place quantitatively. Deuteration experiments show that the silane hydrogen stems from the NH group and that the reaction partially or exclusively proceeds by an intermolecular pathway.

Current status and prospects of new radionuclides and radiopharmaceuticals for cardiovascular nuclear medicine

The rapid emergence of new imaging modalities like positron emission tomography (PET) and single photon emission computerized tomography (SPECT) and their advance into the clinical arena offered new opportunities for, but also stimulated research and development of new radiopharmaceuticals suitable for cardiac imaging. While tracers of myocardial blood flow remained in the center of interest, other trends heralded possibilities of studying more comprehensively cardiac physiology and pathophysiology as, for example, metabolism, the severity of tissue injury, neural activity and membrane function. N-13 ammonia and rubidium-82 became the primary tracers for evaluating and possibly quantifying regional myocardial blood flow with PET, while cationic Tc-99m isonitrile complexes have now reached a stage where high contrast images of the human heart are obtained on planar scintigraphy and SPECT. These radiopharmaceuticals hold considerable promise for routine clinical use. Tracers of metabolism, especially those labeled with positron emitting isotopes as for example, C-11 palmitate, F-18 2-deoxyglucose, are approaching the phase of clinical use and provide information on regional myocardial substrate metabolism and oxidative processes. Less successful and more limited were developments of single photon emitting tracers of metabolism which remained largely confined to radioiodinated fatty acid analogs. Exploration and characterization of the metabolic fate of the radiolabel in tissue and its relation to the externally observed signal have been truly impressive. Tested in humans primarily in western European countries, these tracers promise to yield metabolic information on a more limited scope. Most widely applied are iodohepta- and hexadecanoic acid and, more recently, the aromatic fatty acid analog, paraiodophenylpentadecanoic acid. Labeled monoclonal antibodies rapidly advanced to the point of clinical use. Accurate identification and sizing of acute myocardial infarction is now possible with Tc-99m or indium-111 labeled specific antimyosin antibody fragments. This success stimulated new research activities for use of labeled antibody techniques in other areas as for example, scintigraphic evaluation of formation and presence of vascular thrombi. While promising, these efforts have however remained in an early stage of development. The same holds true for single photon and positron emitting tracers that are suitable for assessing sympathetic neuron densities in myocardium as well as imaging of both cholinergic and adrenergic receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

ChemInform Abstract: Syntheses and Reactions of Acyclic and Cyclic Carbene Complexes cis‐(MI(=CMeNHMe)(CO)2(η‐C5H5)) (M: Mo or W) and Cyclic cis‐(MI(=C(CH2)nNMe)(CO)2(η‐C5H5)) (M: Mo, n = 3 or 4; M: W, n = 3) Obtained Through Alkyl Migration to Methyl Isocyanide Coordinated to Molybdenum or Tungsten. X‐Ray Structure of Cyclic cis‐(MoI(=C(CH2)3NMe)(CO)2(η‐C5H5)).

AbstractReaction of the anionic isonitrile complexes (I) with I‐(CH2)3‐I results in formation of the cis‐carbene complexes (IIa) or (IIb) as the sole isolable products (mechanism).

Investigations of polymerizations and metathesis reactions: Part IX . Metathesis of carbodiimides with tungsten(VI)-imido complexes

In addition to tungsten(0)-carbene and tungsten(0)-isonitrile complexes, we have found tungsten(VI)-imido complexes to be active catalysts for the metathesis of carbodiimides. The reaction products were analyzed by GC/MS and provide some insight into the reaction pathway. The metathesis proceeds by an exchange of imido groups.

Technetium-99m isonitrile complex as a potential myocardial imaging agent.

KHALIL, M. N.1; THORNBACK, J.2; EARLY, M. Y.3; MORTON, D. B.5; BERRY, J. M.4; HUBNER, P. J.B.1 Author Information

Synthesis and characterisation of a series of vanadium isonitrile complexes

The reaction between (η 5-C 5H 5)V(CO) 4 and RNC in the presence of PdO as catalyst to give (η 5-C 5H 5)V(CO) 4 − n (CNR) n ( n = 1–3) is reported. The complexes have been characterized by IR and 51V and 1H NMR spectroscopy.

Neutral and anionic pentafluorophenyl complexes of palladium and platinum(II) and their reactivity towards amines

The (n-Bu4N)[M(C6F5)3(CNR)] complexes (M=Pd or Pt; R=p-Tolyl, Me, Cy ort-Bu, prepared from (n-Bu4N)[M(C6F5)3(tht)] (tht = tetrahydrothiophene) and the appropriate isocyanide, RNC, prove to be unreactive towards benzylamine or MeOH. Thetrans-[Pd(C6F5)2(CNR)2] complexes react slowly with benzylamine to give the corresponding carbene complexestrans-[Pd(C6F5)2{C(NHR)(NHBz)}2], the rate of the reaction decreasing in the order:p-Tolyl > Me > Cy ≫t-Bu (for R=t-Bu the carbene complex cannot be prepared). In the corresponding Pt complexes a marked decrease in reactivity is observed and only the most reactive isonitrile complex (R=p-Tolyl) gives the carbene complextrans-[Pt(C6F5)2{C(NHTolyl-p)(NHBz)}2}. Thecis-[M(C6F5)2(CNTolyl)2] complexes do not show any change in reactivity compared to the correspondingtrans-complexes, and givecis[M(C6F5)2{C(NHTolyl-p)(NHBz)}2].

Bimetallic systems. Part 5. Isonitrile–platinum(II)– or –palladium(II)–bis(diphenylphosphino)methane complexes including heterobimetallics with silver(I), gold(I), or rhodium(I)

Treatment of cis-[PtCl2(dppm-PP′)] with ButNC gives [(ButNC)2Pt(µ-dppm)2Pt(CNBut)2]4+, isolated as the PF6– salt (dppm = Ph2PCH2PPh2). Treatment of [M(dppm-PP′)2]Cl2(M = Pt or Pd) with two equivalents of ButNC or MeNC gave fluxional, mononuclear isonitrile complexes of type [M(CNR)2(dppm-P)2]2+, isolated as their PF6– or BPh4– salts. The palladium salts readily lose the CNR ligands. The unidentate-dppm complexes of type [Pt(CNR)2(dppm-P)2]2+ react with AgPF6, HgCl2, or [Rh2Cl2(CO)4] to give heterobimetallic complexes with µ-dppm ligands, but these were not isolated in a pure state. However, the salts [M(dppm-PP′)2]Cl2(M = Pt or Pd) react with the compounds [AgCl(CNR)](R = Me, But, or p-tolyl) to give the heterobimetallic complexes [(RNC)-CIM(µ-dppm)2AgCl]+ in high yield. These were isolated as Cl–, BPh4–, or PF6– salts. The salt [Pt(CNBut)2(dppm-P)2]Cl2, prepared in situ from [Pt(dppm-PP′)2]Cl2 and ButNC, reacts with [{AgCl(PPh3)}4] or [AuCl(PPh3)] to give [(ButNC) ClPt(µ-dppm)2MCl]Cl (M = Ag or Au). Treatment of [Pt(dppm-PP′)2]Cl2 with [Au(CCPh)(CNBut)] gives [(ButNC)(PhCC)Pt(µ-dppm)2-AuCl]Cl. Treatment of [(ButNC)ClPt(µ-dppm)2AgCl]Cl with [Rh2Cl2(CO)4] gives the complex [(ButNC)ClPt(µ-dppm)2RhCl(CO)][RhCl2(CO)2] and silver chloride in a transmetallation reaction, I.r. and 1H-{31P}, 31P-{1H}, and 195Pt-{1H} n.m.r. data are given and discussed.