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Thomas Pechmann

Publications and source records attributed to Thomas Pechmann.

10 recordsLinked to original sources
PubMed2006

Different interference effects in musicians and a control group.

In the present study musicians and normal control subjects performed an S1-S2 pitch comparison task, which included the presentation of intervening tones during the retention interval. The time for encoding and storing the pitch of S1 was varied between 200 and 1,500 ms by changing the pause between the S1 offset and the onset of the intervening tones. Although musicians outperformed the control group with longer pauses after the S1 offset, this advantage was relatively small with shorter pauses. These results suggest that the advantage of musicians in storing auditory information is not solely due to their superior encoding of information but also to improved working memory operations.

Adolescent↗
PubMed2006

Gender processing in first and second languages: the role of noun termination.

In 2 picture-naming and 2 grammaticality judgment experiments, the authors explored how the phonological form of a word, especially its termination, affects gender processing by monolinguals and unbalanced bilinguals speaking German. The results of the 2 experiments with native German speakers yielded no significant differences: The reaction times were statistically identical for items from gender typical, ambiguous, and gender atypical groups. The 2 experiments with English bilinguals who had learned German as a second language (L2), however, provided evidence that the L2 word's termination plays a role in L2 gender processing. Participants were fastest when producing gender-marked noun phrases containing a noun with a gender typical termination and slowest when the noun had a gender atypical termination. Analogous results were obtained in the grammaticality judgment experiment. These findings support the assumption that there is interaction between the levels of phonological encoding and grammatical encoding at least in bilingual processing.

Adult↗
PubMed2004

Extending the coordination capabilities of tertiary phosphines and arsines: preparation, molecular structure, and reactivity of dinuclear rhodium complexes with PR3 and AsR3 in a doubly bridging coordination mode.

The reactions of [Rh2(kappa2-acac)2(mu-CPh2)2(mu-PR3)] (PR3= PMe34, PMe2Ph 7, PEt38) with an equimolar amount of Me3SiX (X = Cl, Br, I) afforded the unsymmetrical complexes [Rh2X(kappa2-acac)(mu-CPh2)2(mu-PR3)]5, 9-12, which contain the phosphine in a semi-bridging coordination mode. From 4 and excess Me3SiCl, the tetranuclear complex [[Rh2Cl(mu-Cl)(mu-CPh2)2(mu-PMe3)]2]6 was obtained. In contrast, the reaction of 4 with an excess of Me3SiX (X = Br, I) yielded the dinuclear complexes [Rh2X2(mu-CPh2)2(mu-PMe3)]13, 14 in which, as shown by the X-ray crystal structure analysis of 14, the bridging phosphine is coordinated in a truly symmetrical bonding mode. While related compounds with PEt3 and PMe2Ph as bridging ligands were prepared on a similar route, the complex [Rh2Cl2(mu-CPh2)2(mu-PiPr3)]19 was obtained from the mixed-valence species [(PiPr3)Rh(mu-CPh2)2Rh(kappa2-acac)2]17 and HCl. The reaction of [Rh2(kappa2-acac)2(mu-CPh2)2(mu-SbiPr3)]3 with AsMe3 gave the related Rh(mu-AsMe3)Rh compound 21. With Me3SiCl, the acac ligands of 21 can be replaced stepwise by chloride to give [Rh2Cl(kappa2-acac)(mu-CPh2)2(mu-AsMe3)]23 and [[Rh2Cl(mu-Cl)(mu-CPh2)2(mu-AsMe3)]2]24, the latter being isomorphous to the phosphine-bridged dimer 6.

Journal Article↗
PubMed2004

A new family of dinuclear rhodium complexes containing tertiary phosphanes in a semibridging or doubly bridging bonding mode.

The reactions of [Rh(2)Cl(kappa(2)-acac)(mu-CPh(2))(2)(mu-SbiPr(3))] (3) and [Rh(2)(kappa(2)-acac)(2)(mu-CPh(2))(2)(mu-SbiPr(3))] (4) with PMe(3) lead to exchange of the bridging ligand and afford the novel PMe(3)-bridged counterparts 5 and 6, in which the phosphane occupies a semibridging (5) or a doubly bridging (6) position. In both cases, the bonding mode was confirmed crystallographically. Treatment of 6 with CO causes a shift of PMe(3) from a bridging to a terminal position and gives the unsymmetrical complex [(kappa(2)-acac)Rh(mu-CPh(2))(2)(mu-CO)Rh(PMe(3))(kappa(2)-acac)] (7). Similarly to 5 and 6, the related compounds 10 and 11 with one or two acac-f(3) ligands were prepared. While both PEt(3) and PnBu(3) react with 3 by exchange of the bridging stibane for phosphane to give compounds 12 and 13, the reactions of 4 with PMePh(2) and PnBu(3) afford the mixed-valent Rh(0)Rh(II) complexes [(PR(3))Rh(mu-CPh(2))(2)Rh(kappa(2)-acac)(2)] (17, 18) in high yields. In contrast, treatment of 4 with PEt(3) and PMe(2)Ph generates the phosphane-bridged compounds [Rh(2)(kappa(2)-acac)(2)(mu-CPh(2))(2)(mu-PR(3))] (14, 15) exclusively. Stirring a solution of 14 (R=Et) in benzene for 15 h at room temperature leads to complete conversion to the mixed-valent isomer 16. The reaction of 6 with an equimolar amount of CR(3)CO(2)H (R=F, H) or phenol in the molar ratio of 1:10 results in substitution of one acac by one trifluoracetate, acetate, or phenolate ligand without disturbing the [Rh(2)(mu-CPh(2))(2)(mu-PR(3))] core. From 6 and an excess of CR(3)CO(2)H, the symmetrical bis(trifluoracetato) and bis(acetate) derivatives [Rh(2)(kappa(2)-O(2)CCR(3))(2)(mu-CPh(2))(2)(mu-PMe(3))] (21, 22) were obtained.

Journal Article↗
PubMed2004

The time course of recovery for grammatical category information during lexical processing for syntactic construction.

In the experiments outlined in this article, the authors investigate lexical access processes in language production. In their earlier work, T. Pechmann and D. Zerbst (2002) reported evidence for grammatical category constraints in a picture-word interference task. Although grammatical category information was not activated when subjects produced bare noun descriptions of simple objects, a robust effect arose when the target word had to be embedded in a syntactic frame. The current experiments demonstrate that compilation of a simple noun phrase (NP) yields word class effects in picture-word interference experiments in the same time frame as that generally observed for semantic processing. Most significantly, the effect emerges both in German and English with very similar profiles. On these grounds, it is implausible that the effect depends on syntactic gender activation, because such constraints are lacking in the English language version of the experiments.

Humans↗
PubMed2003

Timed picture naming in seven languages.

Timed picture naming was compared in seven languages that vary along dimensions known to affect lexical access. Analyses over items focused on factors that determine cross-language universals and cross-language disparities. With regard to universals, number of alternative names had large effects on reaction time within and across languages after target-name agreement was controlled, suggesting inhibitory effects from lexical competitors. For all the languages, word frequency and goodness of depiction had large effects, but objective picture complexity did not. Effects of word structure variables (length, syllable structure, compounding, and initial frication) varied markedly over languages. Strong cross-language correlations were found in naming latencies, frequency, and length. Other-language frequency effects were observed (e.g., Chinese frequencies predicting Spanish reaction times) even after within-language effects were controlled (e.g., Spanish frequencies predicting Spanish reaction times). These surprising cross-language correlations challenge widely held assumptions about the lexical locus of length and frequency effects, suggesting instead that they may (at least in part) reflect familiarity and accessibility at a conceptual level that is shared over languages.

Cross-Cultural Comparison↗
PubMed2002

A new family of mixed-valence dinuclear rhodium complexes containing the two metal centers in different stereochemical environments.

A series of dinuclear chelate complexes of the general composition [Rh2(kappa2-L)2(mu-CR2)2(mu-SbiPr3)] (R = Ph, p-Tol; L = CF3CO2-, acac-, acac-f3-) and [Rh2Cl(kappa2-L)(mu-CR2)2(mu-SbiPr3)] (R = Ph, p-Tol; L = acac-, acac-f3-) has been prepared by replacement of the chloro ligands in the precursors [Rh2Cl2(mu-CR2)2(mu-SbiPr3)] by anionic chelates. The lability of the SbiPr3 bridge in the rhodium dimers is illustrated by the reactions of [Rh2(kappa2-acac)2(mu-CR2)2(mu-SbiPr3)] (7, 8) with Lewis bases such as CO, CNtBu, and SbEt3 which lead to the formation of the substitution products [Rh2(kappa2-acac)2(mu-CR2)2(mu-L')] (13-16) in excellent yields. Treatment of 7 and 8 with sterically demanding tertiary phosphanes PR3 (R3 = iPr3, iPr2Ph, iPrPh2, Ph3) affords the mixed-valence Rh0-RhII complexes [(kappa2-acac)2Rh(mu-CPh2)2Rh(PR3)] (21-24) and [(kappa2-acac)2Rh(mu-C(p-Tol)2]2Rh(PiPr3)] (25) for which there is no precedence. The terminal PiPr3 ligand of 21 is easily displaced by alkynes, CNtBu, and CO to give, by preserving the [(kappa2-acac)2Rh(mu-CPh2)2Rh] molecular core, the related dinuclear compounds 26-31 in which the coordination number of the Rh0 center is 3, 4, or 5. The molecular structures of [Rh2Cl(kappa2-acac)(mu-CPh2)2(mu-SbiPr3)] (5), [Rh2(kappa2-acac)2(mu-CPh2)2(mu-CO)] (13), [(kappa2-acac)2Rh(mu-CPh2)2Rh(PiPr3)] (21), and [(kappa2-acac)2Rh(mu-CPh2)2Rh(CNtBu)2] (30) have been determined crystallographically.

Journal Article↗
PubMed2002

The activation of word class information during speech production.

In 5 picture-word interference experiments the activation of word class information was investigated. The first experiment, in which subjects used bare nouns to describe the pictures, failed to reveal any interference effect of noun distractor words as opposed to closed-class distractor words. In the next 4 experiments the pictures were named by using a definite determiner and the noun completing a sentence fragment. The data demonstrate that noun distractors interfere more strongly with picture naming than do non-noun distractors. This held for both visual and auditory presentation of the distractor words. The interference effect showed up in a time window where semantic interference can usually be observed, supporting the assumption that at an early stage of lexical access semantic and syntactic activation processes overlap.

Attention↗