Elektronendichteverteilung in einem Metallaphosphan

Henn, Julian; Meindl, Kathrin; Öechsner, Andreas; Schwab, Gerald; Koritsánszky, T.

doi:10.1002/ange.200905470

Cited by 19 publications

(11 citation statements)

References 60 publications

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“…[127] To elucidate the bonding situation at the phosphorus atom in [Me 2 AlA C H T U N G T R E N N U N G (m-Py) 2 P], we determined the charge density distribution. [128] The value of the Laplacian at the P À C BCP is slightly positive for the theoretical calculations (5 [55] This is the first hint against conjugation and thus against a distinct contribution of form a in Scheme 3, despite the short bond path of 1.79 , which might erroneously be taken as an indicator for P=C double-bond character (P À C in phosphabenzene [129] ca. 1.74 and ca.…”

Section: Fe} 2 a C H T U N G T R E N N U N G {(M-p)py 2 }]mentioning

confidence: 95%

Meaningful Structural Descriptors from Charge Density

Stalke

2011

Chemistry A European J

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This paper provides a short introduction to the basics of electron density investigations. The two predominant approaches for the modelling and various interpretations of electron density distributions are presented. Their potential translations into chemical concepts are explained. The focus of the article lies on the deduction of chemical properties from charge density studies in some selected main group compounds. The relationship between the obtained numerical data and commonly accepted simple chemical concepts unfortunately is not always straightforward, and often the chemist relies on heuristic connections rather than rigorously defined ones. This article tries to demonstrate how charge density analyses can shed light on aspects of chemical bonding and reactivity resulting from the determined bonding situation. Sometimes this helps to identify misconceptions and sets the scene for new unconventional synthetic approaches.

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Section: Fe} 2 a C H T U N G T R E N N U N G {(M-p)py 2 }]mentioning

confidence: 95%

Meaningful Structural Descriptors from Charge Density

Stalke

2011

Chemistry A European J

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“…We report herein the synthesis, characterization and single crystal X-ray structure elucidation of [Li{RR¢PCH(X)S(NR¢¢) 2 }] 2 (R¢¢ = t Bu, X = H, RR¢ = Me (1)/Ph (3), R = Me, R¢ = Ph (5); R¢¢ = SiMe 3 , X = H, RR¢ = Me (2); R¢¢ = SiMe 3 , X = Me, RR¢ = Et ( 4), [TMEDA•Li{Ph 2 PCH 2 S(NSiMe 3 ) 2 }] (6), [Mg{Me 2 PCH 2 S(N t Bu) 2 } 2 ] (7), [Mg{Me 2 PCH 2 S(NSiMe 3 ) 2 } 2 ] ( 8) and [Ph 2 PCH 2 (SNSiMe 3 )(HNSiMe 3 )] (9). ‡ ‡ Single-crystal structural analysis: The X-ray data sets were collected at 100(2) K on a Bruker TXS Mo rotating anode (1, 3, 4, 7 (T = 250 K), 8, 9) or an INCOATEC Mo micro source 39 (2, 5, 6) with mirror-monochromated Mo-K a radiation (l = 0.71073 A ˚).…”

Section: Introductionmentioning

confidence: 99%

Access to new Janus head ligands: linking sulfur diimides and phosphanes for hemilabile tripodal scorpionates

2011

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Reactions of lithium dialkyl/phenyl phosphanylmethylides, RR'PCH(X)Li (R, R' = Me, Et, Ph and R = Me, R' = Ph; X = H or Me), with sulfur diimides S(NR'')2 (R'' = (t)Bu or SiMe3) in an equimolar ratio yielded Janus head complexes with the structural motif [Li{RR'PCH(X)S(NR'')2}]2 (R'' = (t)Bu, SiMe3). The basic core of these dimeric complexes is composed of a (LiN)(2) four-membered ring containing two four-coordinated lithium atoms. A lithium complex of the new Janus head ligand with another structural motif [TMEDA·Li{Ph(2)PCH(2)S(NSiMe3)2}] (6) could be isolated from the reaction of [Ph2PCH2Li·TMEDA] with S(NSiMe3)2. Two monomeric complexes [Mg{Me2PCH2S(NR'')2}2] (7, 8) were synthesised by a straightforward reaction of [Li{Me2PCH2S(NR'')2}2] with MgCl2 in pentane. The magnesium atom is chelated by one phosphorus atom and two nitrogen atoms of each unit of the hemilabile ligand in a tripodal manner, leading to octahedral geometry around the magnesium cation. A complete analysis of [Ph2PCH2(SNSiMe3)(HNSiMe3)] (9) is also described in which one nitrogen atom of the imido moiety is protonated.

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“…More about the experimental data can be found in Henn et al (2010). The 2 S residual sum was calculated according to equation (18).…”

Section: Influence Of the Structure Model And Of Intensity And Signifmentioning

confidence: 99%

“…To simplify the procedure, only an IAM model with anisotropic displacement parameters (ADPs) was generated from a refinement against experimental data. More about the experimental data can be found in Henn et al (2010). The 2 S residual sum was calculated according to equation (18).…”

Section: Influence Of the Structure Model And Of Intensity And Signifmentioning

confidence: 99%

About systematic errors in charge-density studies

Henn¹,

Meindl

2014

Acta Cryst Sect A

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The formerly introduced theoretical R values [Henn & Schönleber (2013). Acta Cryst. A69, 549-558] are used to develop a relative indicator of systematic errors in model refinements, R(meta), and applied to published charge-density data. The counter of R(meta) gives an absolute measure of systematic errors in percentage points. The residuals (Io - Ic)/σ(Io) of published data are examined. It is found that most published models correspond to residual distributions that are not consistent with the assumption of a Gaussian distribution. The consistency with a Gaussian distribution, however, is important, as the model parameter estimates and their standard uncertainties from a least-squares procedure are valid only under this assumption. The effect of correlations introduced by the structure model is briefly discussed with the help of artificial data and discarded as a source of serious correlations in the examined example. Intensity and significance cutoffs applied in the refinement procedure are found to be mechanisms preventing residual distributions from becoming Gaussian. Model refinements against artificial data yield zero or close-to-zero values for R(meta) when the data are not truncated and small negative values in the case of application of a moderate cutoff Io > 0. It is well known from the literature that the application of cutoff values leads to model bias [Hirshfeld & Rabinovich (1973). Acta Cryst. A29, 510-513].

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Elektronendichteverteilung in einem Metallaphosphan

Cited by 19 publications

References 60 publications

Meaningful Structural Descriptors from Charge Density

Meaningful Structural Descriptors from Charge Density

Access to new Janus head ligands: linking sulfur diimides and phosphanes for hemilabile tripodal scorpionates

About systematic errors in charge-density studies

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