Replacement Of Phenyl Research Articles

Role of Perfluorophenyl Group in the Side Chain of Small-Molecule n-Type Organic Semiconductors in Stress Stability of Single-Crystal Transistors.

Operational stability, such as long-term ambient durability and bias stress stability, is one of the most significant parameters in organic thin-film transistors (OTFTs). The understanding of such stabilities has been mainly devoted to energy levels of frontier orbitals, thin-film morphologies, and device configuration involving gate dielectrics and electrodes, whereas the roles of molecular and aggregated structural features in device stability are seldom discussed. In this Letter, we report a remarkable enhancement of operational stability, especially bias stress, of n-channel single-crystal OTFTs derived from a replacement of phenyl with perfluorophenyl groups in the side chain. Because of the several-molecule-thick single-crystal nature employed for the OTFTs, the crystal-surface properties are thought to be critical, where the surface structure composed of perfluorophenyl moieties could suppress interactions between environmental species and field-induced carriers owing to increased hydrophobicity and steric protection of π-conjugated units.

Phenolic nitroaromatics detection by fluorinated metal-organic frameworks: Barrier elimination for selective sensing of specific group of nitroaromatics

Many piesce of research have been performed to detect nitroaromatic-compounds (NACs) by metal-organic frameworks (MOFs). Despite extensive studies, there are still significant challenges like selective detection of specific NAC group in presence of other NACs. Here, we have integrated two functionalization strategies through decoration of pore-walls of the MOFs with trifluoromethyl groups and extension in π-conjugated system. Based on this idea, trifluoromethyl TMU-44 (with the formula [Zn2(hfipbb)2(L1)]n.DMF, H2hfipbb = 4,4′-(hexafluoroisopropylidene) bis(benzoic acid), L1 = N,N′-bis-pyridin-4-ylmethylene-benzene-1,4-diamine) and TMU-45 (with formula [Zn2(hfipbb)2(L2)]n.DMF, L2 = N,N′-bis-pyridin-4-ylmethylene-naphthalene-1,5-diamine) frameworks have been synthesized. The aromatic skeleton of TMU-44 is based on phenyl rings while TMU-45 aromatic skeleton is extended by replacement of phenyl with naphthyl core. Measurements reveal that these MOFs are highly sensitive to phenolic NACs especially 2,4,6-trinitrophenol (TNP) with high quenching efficiency of 90% for TMU-44 (KSV = 10,652 M−1, LOD = 6.9 ppm) and 99% for TMU-45 (KSV = 34,741 M−1, LOD = 2.07 ppm). The proposed detection mechanism can be associated with hydrogen bonding between OH group of phenolic NACs and trifluoromethyl groups of TMU-MOFs as well as π(rich)∙∙∙π(deficient) interaction between π-conjugated backbone of TMU-frameworks and π-deficient ring of NACs.

Investigation of a Bicyclo[1.1.1]pentane as a Phenyl Replacement within an LpPLA2 Inhibitor.

We describe the incorporation of a bicyclo[1.1.1]pentane moiety within two known LpPLA2 inhibitors to act as bioisosteric phenyl replacements. An efficient synthesis to the target compounds was enabled with a dichlorocarbene insertion into a bicyclo[1.1.0]butane system being the key transformation. Potency, physicochemical, and X-ray crystallographic data were obtained to compare the known inhibitors to their bioisosteric counterparts, which showed the isostere was well tolerated and positively impacted on the physicochemical profile.

2-hydroxyisoquinoline-1,3(2H,4H)-diones (HIDs) as human immunodeficiency virus type 1 integrase inhibitors: Influence of the alkylcarboxamide substitution of position 4

Herein, we report further insight into the biological activities displayed by the 2-hydroxyisoquinoline-1,3(2H,4H)-dione (HID) scaffold. Previous studies have evidenced the marked fruitful effect of substitution of this two-metal binding pharmacophore at position 4 by phenyl and benzyl carboxamido chains. Strong human immunodeficiency virus type 1 integrase (HIV-1 IN) inhibitors in the low nanomolar range with micromolar (even down to low nanomolar) anti-HIV activities were obtained. Keeping this essential 4-carboxamido function, we investigated the influence of the replacement of phenyl and benzyl groups by various alkyl chains. This study shows that the recurrent halogenobenzyl pharmacophore found in the INSTIs can be efficiently replaced by an n-alkyl group. With an optimal length of six carbons, we observed a biological profile and a high barrier to resistance equivalent to those of a previously reported hit compound bearing a 4-fluorobenzyl group.

Fluorometric assay of lipase by some new synthetized fluorescein aralkyl esters

A series of fluorescein aralkyl esters were synthesized through esterification of fluorescein with carboxylic acids or acyl chlorides and applied to the fluorometric assay of lipase. The rate of spontaneous hydrolysis and enzymatic hydrolysis was measured by monitoring of fluorescence intensities of the solution and correlated with the enzyme activity. In addition, the chain length effect of aralkyl fluorescein esters was studied. Fluorescein di(5-phenylpentanoate) was found to be a better substrate than their homologs for the fluorometric assay of lipase with the higher rate of hydrolysis and better K m value. As little as 15 ng mL−1 of lipase can be detected with fluorescein di(5-phenylpentanoate). Substitute’s effects on the enzymatic hydrolysis of phenyl acetic acid and replacement of phenyl with other polycyclic aromatics such as biphenyl or naphthyl showed a decrease in enzymatic hydrolysis rate.

Synthesis and Characterization of Thermosetting Furan-Based Epoxy Systems

Renewable alternatives to petroleum-based thermosetting polymers have drawn significant attention due to potential positive economic and ecological impact. New materials should mimic the rigid, phenylic structure of incumbent high-performance thermoset monomers. Furans derived from cellulose and hemicellulose are promising candidates for phenyl replacement. The synthesis of furan-based diepoxies is challenging, and direct property comparisons of thermosets prepared using furanyl and phenyl-based epoxy monomer analogues are required. In this work, analogous furanyl-based and phenyl-based diepoxy monomers were synthesized, and thermosets were prepared using amine curing agents. A structure–property study showed that furan-based polymers possess improved Tg (Δ = 8–16 °C) and improved glassy modulus (Δ = 0.1 to 0.6 GPa) relative to their phenylic analogues. The furan ring has thus been demonstrated to be a viable building block for renewable high-performance epoxies, with potential for application in other th...

Effect of the isosteric replacement of the phenyl motif with furyl (or thienyl) of 4-phenyl-N-arylsulfonylimidazolones as broad and potent anticancer agents

To investigate the effect of isosteric replacement of phenyl with heteroaromatics of 4-phenyl-N-arylsulfonylimidazolones (1–4) as broad and potent anticancer agents, a series of 4-furyl (5a–e, 7a–c) or thienyl-N-arylsulfonylimidazolones (6a–e) were designed and synthesized to evaluate their in vitro anticancer activity against HCT116, A549 and NCI-H460 cancer cell lines. Replacement of phenyl with furyl or thienyl slightly reduced the activity, however, these analogs showed comparable activity to doxorubicin. The thienyl analogs exhibited more potent activity than furyl analogs due to their more isosteric similarity with the phenyl moiety. In addition, the carbamate derivatives (5a–e and 6a–e) of both the analogs had better activities than the carbamoyl derivatives (7a–c). Therefore, the size and planarity of the aryl motif at 4-position of N-arylsulfonylimidazolones are crucial for their anticancer activity.

ChemInform Abstract: N-(3-Benzo[b]thienyl)iminophosphoranes Toward the Synthesis of Benzo[b]thieno[3,2-b]pyridines: Reactivity and Alternative Regioselectivity with α,β-Unsaturated Ketones and Aldehydes.

Abstract The novel N-(3-benzo[b]thienyl)iminophosphoranes 1b–d react with α,β-unsaturated aldehydes and ketones 2a–e to give varying mixtures of the regioisomeric benzothieno[3,2-b]pyridines 3a–d and 4a–d as a result of preferential attack of either imino nitrogen or α-thienyl carbon at the enone carbonyl group. The findings indicate that the progressive replacement of phenyl with methyl P-substituent greatly enhances the reactivity of the phosphorane 1 and concomitantly enhances the propensity of the phosphorane itself for addition to the enone by the α-thienyl carbon.

Steric vs. electronic anomaly observed from iodomethane oxidative addition to tertiary phosphine modified rhodium(i) acetylacetonato complexes following progressive phenyl replacement by cyclohexyl [PR3 = PPh3, PPh2Cy, PPhCy2 and PCy3

Rhodium(i) acetylacetonato complexes of the formula [Rh(acac)(CO)(PR(3))] [acac = acetylacetonate, PR(3) = PPh(3) 1, PCyPh(2) 2, PCy(2)Ph 3, PCy(3) 4] were synthesized and the iodomethane oxidative addition to these complexes were studied. Spectroscopic and low temperature (100 K) single crystal X-ray crystallographic data of the rhodium complexes (1-4) indicate a systematic increase in both steric and electronic parameters of the phosphine ligands as phenyl groups on the tertiary phosphine are progressively replaced by cyclohexyl groups in the series. Second order rate constants for the alkyl formation in the oxidative addition of iodomethane in dichloromethane at 25 degrees C vary with approximately one order-of-magnitude from 6.98(6) x 10(-3) M(-1)s(-1) (PCyPh(2)) to 55(1) x 10(-3) M(-1) s(-1) (PCy(2)Ph 3) and do not follow the expected electronic pattern from to 1-4, which indicates a flexibility of the cyclohexyl group, significantly influencing the reactivity. Activation parameters for the reactions range from 35(3) to 44(1) kJ mol(-1) for DeltaH( not equal) and -140(5) to -154(9) J K(-1) mol(-1) for DeltaS( not equal), and are supporting evidence for an associative activation for the oxidative addition step.

Synthesis, structures and catalytic properties of palladacycles derived from N,N-dimethylaminomethylferrocene

Palladacycles 2 – 4 containing the N , N -dimethylaminomethylferrocenyl backbone and three pyridine co-ligands have been prepared and structurally characterized. Their catalytic activities in promoting the methanolysis of the pesticide parathion were investigated. Cyclopalladated complexes with a N , N -dimethylaminomethylferrocenyl (dmaf) backbone and three pyridine co-ligands, [Pd{(η 5 -C 5 H 5 )Fe[(η 5 -C 5 H 3 )CH 2 NMe 2 ]}Cl(R-Py)] ( 2 : R = 4-H; 3 : R = 4-cyano; 4 : 4- N , N -dimethylamino) have been synthesized and characterized. The single crystal X-ray diffraction analyses show that the palladium(II) in both 3 or 4 is coordinated in a distorted square planar geometry with the two nitrogen atoms trans to each other. The three palladacyles were shown to greatly catalyze the methanolysis of the P S containing pesticide parathion but showed different accelerations. It was found that the replacement of phenyl by ferrocenyl in the palladacycle backbone of 2 lowers the kinetic pKa s s of the Pd-(HOCH 3 ) required for activity by almost 2 units.

Palladiumdichloride (ferrocenylethynyl)phosphanes and their use in Pd-catalyzed Heck–Mizoroki- and Suzuki–Miyaura carbon–carbon cross-coupling reactions

In this work the synthesis of phosphane selenides (FcC C) n Ph 3− n P Se ( 2a, n = 1; 2b, n = 2; 2c, n = 3; Fc = ferrocenyl, (η 5-C 5H 4)(η 5-C 5H 5)Fe) from (FcC C) n Ph 3− n P ( 1a, n = 1; 1b, n = 2; 1c, n = 3) and selenium is described to estimate the σ-donor properties of these systems by 31P{ 1H} NMR spectroscopy. Progressive replacement of phenyl by ferrocenylethynyl causes a shielding of the phosphorus atom with increasing of the 1 J( 31P– 77Se) coupling constants. The palladiumdichloride metal-organic complexes [((FcC C) n Ph 3− n P) 2PdCl 2] ( 3a, n = 1; 3b, n = 2; 3c, n = 3) have been used as (pre)catalysts in the Suzuki–Miyaura (reaction of 2-bromo-toluene ( 4a) and 4-bromo-acetophenone ( 4b), respectively, with phenyl boronic acid ( 5) to give 2-methyl biphenyl ( 6a) and 4-acetyl biphenyl ( 6b)) and in the Heck–Mizoroki reaction (treatment of iodobenzene ( 7) with tert-butyl acrylate ( 8) to give E- tert-butyl cinnamate ( 9)). The structures of molecules 1a, 1c, 2c, and 3c in the solid state were determined by single X-ray structure analysis showing that the structural parameters of these systems are unexceptional and correspond to those of related phosphanes, seleno phosphanes, and palladium dichloride complexes.

Theoretical study on the substituent effect of a Wittig reaction

The substituent effects of F, H and methyl (Me) in replacement of phenyl (Ph) groups bonding with the ylide phosphorus in Wittig reactions have been examined theoretically by performing ab intio calculations. It is shown that the energy barrier for the Wittig reaction with F as the substituent is much higher than that with H, Me and Ph. The Wittig reaction is found to be more favorable with the substituent in the order F<H<Ph<Me. The reactions are found to proceed through two transition states: the formation and the decomposition of oxaphosphetane. We conclude that only the model of the Wittig reaction in which Ph is simplified to Me can reasonably describe the real Wittig reaction.

A transient form of 2-aza-21-carbaporphyrin prearranged for fusion: DFT studies

The formation mechanism of the fused porphyrin (CTPPH-NF) involves a rotation of the N(2) pyrrole ring of 2-aza-21-carba-5,10,15,20-tetraarylporphyrin (CTPPH2) which is subsequently followed by formation of the C(3)–N(24) bond to yield the macrocycle with the fused pyrrole tripentacyclic ring. To approach the problem of the relative stability of the prearranged transient species theoretical investigations have been performed applying density functional theory (DFT). The molecular structures and electronic energy have been studied for idealized 2-aza-21-carbaporphyrin (CPPH2) and porphyrin (PH2) macrocycles created by a replacement of phenyl or other substituents with hydrogen or methyl groups. The following forms of 2-aza-21-carbaporphyrin and porphyrin were studied: CPH2-I, 2-NH-CPH-I and PH2-I in relation to CPH2-P, 2-NH-CPH-P and PH2-P, respectively (P indicates regular geometry (N(21) or C(21) located in the inner perimeter) and I indicates inverted geometry (N(21) or C(21) located in the outer perimeter). A π delocalization exists through the inverted macrocycles: PH2-I, CPH2-I and 2-NH-CPH-I. The B3LYP/6-31G** optimized bond distances of I macrocycles reproduce the pattern of the P counterparts. The B3LYP/6-31G**//B3LYP/6-31G** calculated energy differences between the P and I structures are very similar for two considered 2-aza-21-carbaporphyrin tautomers: CPH 2-P → CPH 2-I, 18.50 kcal mol-1, 2- NH - CPH -P → 2- NH - CPH -I, 17.55 kcal mol-1; but essentially different for the regular porphyrin PH2-P → PH 2-I, 45.56 kcal mol-1. The methyl substitution at the 21-carbon or 5 and 20 meso positions preserved the order of stability as the calculated energy differences equal 21- CH 3- CPH 2-P → 21- CH 3- CPH 2-I, 13.39 kcal mol-1; 5,20- CH 3- CPH 2-P → 5,20- CH 3- CPH 2-I, 17.87 kcal mol-1.

Pyrrole-inverted isomer of 5,10,15,20-tetraaryl-21-selenaporphyrin

A novel 5,10,15,20-tetraaryl-21-selenaporphyrin isomer with an inverted pyrrole ring, i.e., 5,10,15, 20-tetraaryl-2-aza-21-carba-22-selenaporphyrin (SeC-TArPH) has been produced by a [3 + 1] condensation of 2, 5-bis(phenylhydroxymethyl)selenophene and 5,10-ditolyltripyrrin. The reaction yielded 5,20-diphenyl-10,15-bis(p-tolyl)-21-selenaporphyrin Se-DPDTPH (19%) and its isomer with an inverted pyrrole ring, i.e., 5,10-diphenyl-15,20-bis(p-tolyl)-2-aza-21-carba-22-selenaporphyrin, SeC-DPDTPH (1%). Mechanistically the synthesis of SeC-DPDTPH requires one beta-condensation at the pyrrole moiety of 5, 10-ditolyltripyrrin instead of the stereotypical alpha-condensation. The identity of inverted selenaporphyrin has been confirmed by high-resolution mass spectrometry and (1)H NMR spectroscopy. A saddle distortion mode for the inverted selenaporphyrin macrocycle SeC-DPDTPH has been determined by X-ray crystallography. NMR spectra are consistent with the existence of tautomeric equilibria that involve three tautomeric species of the neutral form of SeC-DPDTPH. The preference for the tautomer with the labile proton located at the peripheral N(2) nitrogen atom has been detected in pyridine-d(5) solution. The density functional theory (DFT) has been applied to determine the molecular and electronic structure of three tautomers of 2-aza-21-carba-22-selenaporphyrin: 2-N, 23-N, 24-NH, 2-N, 23-NH, 24-N, and 2-NH, 23-N, 24-N formally created from SeC-DPDTPH by a replacement of phenyl and tolyl groups with hydrogen. The total energies calculated using the B3LYP/6-311G//B3LYP/6-311G approach, demonstrate that relative stability of postulated tautomers decreases in the order 2-N, 23-NH, 24-N > 2-N, 23-N, 24-NH > 2-NH, 23-N, 24-N. The small energy differences between tautomeric species suggests their simultaneous presence in equilibrium.

N-(3-Benzo[ b]thienyl)iminophosphoranes toward the Synthesis of Benzo[ b]thieno[3,2- b]pyridines: Reactivity and Alternative Regioselectivity with α,β-unsaturated Ketones and Aldehydes

The novel N-(3-benzo[ b]thienyl)iminophosphoranes 1b– d react with α,β-unsaturated aldehydes and ketones 2a– e to give varying mixtures of the regioisomeric benzothieno[3,2- b]pyridines 3a– d and 4a– d as a result of preferential attack of either imino nitrogen or α-thienyl carbon at the enone carbonyl group. The findings indicate that the progressive replacement of phenyl with methyl P-substituent greatly enhances the reactivity of the phosphorane 1 and concomitantly enhances the propensity of the phosphorane itself for addition to the enone by the α-thienyl carbon.

Organometallic complexes for nonlinear optics. 15. Molecular quadratic hyperpolarizabilities of trans-bis{bis(diphenylphosphino)methane}ruthenium σ-aryl- and σ-pyridyl-acetylides: X-ray crystal structure of trans-[Ru(2-CCC 5H 3N-5-NO 2)Cl(dppm) 2

The complexes trans-[Ru(2-CCC 5H 3N-5-R)Cl(dppm) 2] [R=H ( 6), NO 2 ( 7)] have been prepared and 7 has been structurally characterized; comparison with the structural study of trans-[Ru(4-CCC 6H 4NO 2)Cl(dppm) 2] ( 3) reveals a decrease in Ru–C(1) distance and increase in Ru–Cl(1) distance, consistent with stronger σ-bonding by the nitropyridylalkynyl ligand in 7 compared to the nitrophenylalkynyl ligand in 3. Electrochemical data for 3, 6, 7, precursor dichloro complexes [RuCl 2(dppm) 2] [ cis ( 1a), trans ( 1b)], and related alkynyl complexes trans-[Ru(4-CCC 6H 4R)Cl(dppm) 2] [R=H ( 2), 4-C 6H 4NO 2 ( 4), ( E)-4-CHCHC 6H 4NO 2 ( 5)] have been determined by cyclic voltammetry. Introduction of nitro substituent in progressing from 2 to 3 or 6 to 7 leads to a substantial increase in E o Ru II/III, most of which is lost on chain-lengthening the alkynyl ligand in progressing from 3 to 4 or 5. Replacement of phenyl by pyridyl in progressing from 2 to 6 or 3 to 7 results in a 0.1 V increase in E o Ru II/III. The optical spectra of representative complexes have been examined. Introduction of a nitro substituent onto the phenylalkynyl ligand, in progressing from 2 to 3, results in a substantial (ca. 11 000 cm −1) red-shift in the intense MLCT band of the Ru II–CC–Ar–NO 2 moiety. Complexes 3, 4 and 5 exhibit sizable solvatochromic shifts, suggestive of significant optical nonlinearities. Quadratic hyperpolarizabilities for 2– 7 were determined by hyper-Rayleigh scattering (HRS) at 1064 nm; measurements are consistent with an increase in β HRS upon incorporation of nitro substituent (progressing from 2 to 3 or 6 to 7), chain-lengthening the alkynyl ligand (progressing from 3 to 4 and then to 5) and replacing phenyl by pyridyl in progressing from 2 to 6, general trends that are maintained with the two-level-corrected data, and which parallel shifts in λ max to low energy. The observed and two-level-corrected β HRS values for 7 are lower than expected; it is perhaps significant that λ max for 7 is close to the second-harmonic.

Novel Organometallic Compounds for Nonlinear Optics

Hyper-Rayleigh scattering is used to investigate the nonlinear optical properties of novel metal (ruthenium, nickel and gold) σ-arylacetylide complexes. The influence of the organometallic donor group and conjugating bridge on the quadratic hyperpolarizability is studied. For all organic ligands, the addition of the metal (donor) group is shown to increase the static hyperpolarizability by a factor of 2, 4 and 7 for gold, nickel and ruthenium complexes, respectively. Moreover, replacement of phenyl with a heterocyclic ring is demonstrated to enlarge the hyperpolarizability in the case of gold and ruthenium compounds.

Structure and Stability of 2-Aza-21-carbaporphyrin Tautomers Prearranged for Coordination

2-Aza-21-carba-5,10,15,20-tetraarylporphyrin (CTPPH2, inverted porphyrin) and its methylated derivatives, acting as ligands, can be structurally related to the following hypothetical tautomers: 2-aza-5,10,15,20-tetraphenyl-21-carbaporphyrin (2-NH-CTPPH); 2-aza-5,10,15,20-tetraphenyl-21-methyl-21-carbaporphyrin (21-H-21-CH3CTPPH); 2-aza-5,10,15,20-tetraphenyl-21-methyl-21-carbaporphyrin (2-NH-21-CH3CTPPH); 2-aza-2,21-dimethyl-5,10,15,20-tetraphenyl-21-carbaporphyrin (2-NCH3-21-CH3CTPPH). Their structures and electronic energies have been investigated applying the density functional theory (DFT) for idealized 21-carbaporphyrin, created by a replacement of phenyl and methyl groups with hydrogen, yielding CPH2, 21-H-CPH, 2-NH-CPH, and 2-NH-21-H-CP. The B3LYP/6-31G optimized bond lengths and angles of 21-carbaporphyrin skeletons are in satisfactory agreement with X-ray crystallographic values when compared in structurally related pairs, i.e., CPH2 and CTPPH2, 21-H-CPH and (21-CH3TPP)NiII, and 2-NH-CPH and (2-NCH3-21-CH3CTPP)NiIII. The calculated total electronic energies, using the B3LYP/6-31-G**//B3LYP/6-31G approach, demonstrate that relative stability of the postulated tautomers decreases in the order CPH2 > 21-H-CPH > 2-NH-CPH ≫ 2-NH-CPH2 > 2-NH-21-H-CP. The difference between the electronic energy of the regular porphyrin PH2 and the fundamental tautomer 21-carbaporphyrin CPH2 is calculated to be 20.41 kcal/mol. The DFT calculation reproduced properly the distribution of mobile protons for the tautomer of the lowest energy for each stable 21-carbaporphyrin and provided some insight into the analysis of energy required for the suggested prearrangement process imposed by insertion of a metal ion. The spectacular flexibility of the ligand structure including a reversible trigonal-pyramidal geometry change at the C(21) center has been also discussed.

Syntheses and quadratic hyperpolarizabilities of some (pyridylalkynyl)metal complexes: crystal structures of [Ni{2-(CC)C5H3NNO2-5}(PPh3)(η-C5H5)], [Au{2-(CC)C5H3NNO2-5}(PPh3)] and [Au{2-(CC)C5H4N}(PPh3)] ‡

The complexes [Ru{2-(CC)C5H3NR-5}(PPh3)2(η-C5H5)] (R = NO2 1 or H 2), [Ni{2-(CC)C5H3NR-5}(PPh3)(η-C5H5)] (R = NO2 3 or H 4) and [Au{2-(CC)C5H3NR-5}L] (L = PPh3, R = NO2 5 or H 6; L = PMe3, R = NO2 7) have been synthesized and 3, 5 and 6 structurally characterized; no significant increase in quinoidal vinylidene contribution to the acetylide ground-state structure is apparent on progression from structurally characterized phenylacetylide complexes to the new pyridylacetylide complexes, or upon replacement of 5-H by 5-NO2 in progressing from 6 to 5. The molecular quadratic optical non-linearities of 1–7 have been determined by hyper-Rayleigh scattering (HRS). The HRS measurements at 1064 nm are consistent with an increase in β upon replacement of phenyl by an N-heterocyclic ring (replacing a nitrophenylacetylide by a nitropyridylacetylide ligand) for the ruthenium and gold systems, but with no change for the nickel complexes, and with an increase in non-linearity upon replacement of PMe3 by PPh3 in progressing from 7 to 5. The bulk second-order susceptibilities of the series have been determined by Kurtz powder measurements at 1064 nm, with the only significant response (about eight times that of urea) being that of 3; this complex was the only one of the three structurally characterized to pack non-centrosymmetrically in the crystal lattice. Electrochemical data for 1–4 have been obtained; comparison to analogous nitrophenylacetlylide complexes reveals that replacing nitrophenylacetylide by nitropyridylacetylide leads to a significant increase in MII/III oxidation potential for the ruthenium complexes, but to no change for the nickel examples. The parameter E°MII/III – E°NO2/NO2– was evaluated for 1–4, results for M = Ru vs. Ni being consistent with experimentally determined non-linearities, i.e. smaller ΔE° and larger non-linearities for ruthenium vs. nickel.

Über Tetraaryl-methan-analoga in der gruppe 14: II. Ph 4- nSi- p-Tol n und Ph 4- nSn- p-Tol n ( n = 0 bis 4): Einfluß der p-tolyl-substituenten auf struktur und NMR-chemische verschiebungen

The title compounds have been synthesized by Li and Grignard reactions. The crystal structure of Ph 3Si- p-Tol has been determined. The substitution of only one phenyl by one p-tolyl group causes only a slight deviation from the ideal S 4 symmetry of Ph 4Si. Gradual replacement of phenyl by p-tolyl groups leads to increasing low field shifts for all 13C( ipso) atoms. The substitution of the first phenyl group by p-tolyl in Ph 4Si and Ph 4Sn results in a high field shift both for δ( 29Si) (−0.3 ppm) and for δ( 119Sn) (−1 ppm). Further replacement shows nearly linear dependencies (Δδ( 29Si) = −0.1 ppm, Δδ( 119Sn) = + 1.5 ppm per p-tolyl group).