Spectroscopic and structural investigation of the unbridged dirhodium cation [Rh2(CH3CN)10]4+

Dunbar, Kim R.

doi:10.1021/ja00232a054

Cited by 74 publications

(33 citation statements)

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“…1) consisted of 12 rods, [2]staffanes terminally substituted with two carboxylates (4), attached to nine dirhodium tetracation (31,32) connectors whose axial positions were occupied by CH 3 CN ligands on top and HCN ligands at the bottom, except for the central bottom position used to hold the nitrile group at the end of the propeller axis. The rotor has been described in ref.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Molecular dynamics of a grid-mounted molecular dipolar rotor in a rotating electric field

Vacek

Michl

2001

Proc. Natl. Acad. Sci. U.S.A.

104

103

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Classical molecular dynamics is applied to the rotation of a dipolar molecular rotor mounted on a square grid and driven by rotating electric field E() at T Ӎ 150 K. The rotor is a complex of Re with two substituted o-phenanthrolines, one positively and one negatively charged, attached to an axial position of Rh 2 4؉ in a [2]staffanedicarboxylate grid through 2-(3-cyanobicyclo[1.1.1]pent-1-yl)malonic dialdehyde. Four regimes are characterized by a, the average lag per turn: (i) synchronous (a < 1͞e) at E() ‫؍‬ ͦE()ͦ > Ec() [Ec() is the critical field strength], (ii) asynchronous (1͞e < a < 1) at Ec() > E() > Ebo() > kT͞, [Ebo() is the break-off field strength], (iii) random driven (a Ӎ 1) at E bo() > E() > kT͞, and (iv) random thermal (a Ӎ 1) at kT͞ > E(). A fifth regime, (v) strongly hindered, W > kT, E, (W is the rotational barrier), has not been examined. We find E bo()͞kVcm ؊1 Ӎ (kT͞)͞kVcm ؊1 ؉ 0.13(͞GHz) 1.9 and E c()͞kVcm ؊1 Ӎ (2.3kT͞)͞kVcm ؊1 ؉ 0.87(͞GHz) 1.6 . For > 40 GHz, the rotor behaves as a macroscopic body with a friction constant proportional to frequency, ͞eVps Ӎ 1.14 ͞THz, and for < 20 GHz, it exhibits a uniquely molecular behavior.M olecular construction kits promise access to giant molecules shaped like regular grids and scaffolds carrying active and͞or mobile groups (1-4). A sturdy artificial square grid polymer, albeit irregular and only ϳ150 nm across, has been reported (5, 6), and time appears right to use computer simulation of these ''designer solids'' to analyze the role of thermal motion in molecular machinery and to identify the best synthetic targets.One of the active elements proposed (4, 7) for incorporation in these molecular scaffolds is a dipolar rotor, capable of rotational motion in response to an outside driving force. Molecular rotors driven unidirectionally by light (8), or bidirectionally by heat (9-12) or chemically (13, 14) have been synthesized. Alternating electric field has been used to affect intramolecular motion (15), and intense laser field of rapidly rotating linear polarization has been used to drive the rotation of a chlorine molecule (16). Free hydroxyl groups on oxide surfaces behave as two-dimensional arrays of interacting rotors, as do phospholipids in certain membranes and dipolar molecules adsorbed on flat surfaces or intercalated in layered solids (17). Biological motors (18) are under study. The velocity at which a dissolved chiral molecule is propelled through a solution by circularly polarized microwaves has been theoretically estimated (19)(20)(21).Previously (22), we examined computationally the unidirectional motion of a grid-mounted propeller-shaped rotor driven by a stream of gas. This windmill rotor acted as a microphone, transducing linear motion of gas molecules into rotational motion of electric charges. A propeller-shaped rotor driven by a rotating electric field in the presence of a gas might produce a pressure differential, acting as a loudspeaker or a gas pump.The dielectric response of a dipolar rotor is intrinsically nonlinear and ther...

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Section: Methods Of Calculationmentioning

confidence: 99%

Molecular dynamics of a grid-mounted molecular dipolar rotor in a rotating electric field

Vacek

Michl

2001

Proc. Natl. Acad. Sci. U.S.A.

104

103

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“…3+ [43] or for [M II , Rh II , where the ñ CN band shifts to higher wavenumber with respect to free MeCN (M = Mo, [46] Tc, [47] Rh [48] ). Therefore, shifting ñ CN to higher values, while the general trend, may not always occur, particularly if backbonding is significant.…”

Section: A C H T U N G T R E N N U N G (Nh 3 ) 5 -A C H T U N G T R Ementioning

confidence: 99%

Tetracyanoethylene (TCNE): The Characteristic Geometries and Vibrational Absorptions of Its Numerous Structures

2006

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Tetracyanoethylene (TCNE) undergoes numerous reactions and is reported to exist in many structural motifs. Identification of these forms and motifs can be challenging. Nonetheless, the number of nu(CN) absorptions and their frequencies provide insight with respect to the specific forms and charge on the TCNE fragment. Particularly informative is the average of the fundamental nu(CN) bands, as well as the length of the central C-C bond. This Review discusses the assignment of structure and formal charge for TCNE-containing compounds. Scrutiny of previous assignments reveals some discrepancies which are discussed, and provides a basis for further study of TCNE structure-function relationships. Several multimetal complexes with bridging [TCNE](z) units exhibit mixed valency and extensive delocalization. The scarcity of suitable model compounds, especially those with M(d(pi-pi*)) backbonding to the CN groups, have thwarted the detailed description of these valence ambiguous compounds; thus, new well-characterized polynuclear compounds are needed.

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“…Da außerdem die Stärke des elektronischen Dipols in [TCNE] z zunimmt, wenn z negativer wird, steigt dementsprechend auch die Intensität der ñ CN -Absorption. Die ñ CN -Banden von TCNE 0 sind daher [46] Tc, [47] Rh [48] ) wird dieses Verhalten nicht beobachtet; hier ist die ñ CN -Absorption gegenüber der von freiem MeCN zu höheren Wellenzahlen verschoben. Die Verschiebung der ñ CN -Absorption zu höheren Werten ist also zwar die allgemeine Tendenz (Abbildung 4, Tabelle 3).…”

Section: Infrarotspektrenunclassified

Tetracyanethylen: die charakteristischen Geometrien und Schwingungsabsorptionen seiner zahlreichen Strukturen

Miller

2006

Angewandte Chemie

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Tetracyanethylen, TCNE, geht zahlreiche chemische Reaktionen ein, und in der Literatur werden für diese Verbindung viele Strukturmotive beschrieben, deren Identifizierung oft schwierig ist. Die Zahl der $\tilde \nu $CN‐Absorptionen und die dazugehörigen Wellenzahlen geben einen Einblick in die jeweilige Struktur und Ladung des TCNE‐Fragments. Besonders die Mittelwerte der Wellenzahlen der fundamentalen νCN‐Schwingungen und die Länge der zentralen C‐C‐Bindung liefern wichtige Informationen. In diesem Aufsatz diskutieren wir die Bestimmung von Struktur und Formalladung von TCNE‐Fragmenten. Wir diskutieren Unstimmigkeiten, die sich bei Überprüfung älterer Strukturzuordnungen ergeben, und liefern eine Grundlage für zukünftige Untersuchungen der Struktur‐Eigenschafts‐Beziehungen von TCNE. Viele Komplexe mit verbrückendem [TCNE]z zeigen gemischte Valenz und ausgeprägte Delokalisierung. Der Mangel an geeigneten Modellverbindungen, besonders solchen mit M‐Rückbindung zu den CN‐Gruppen, hat bisher eine detaillierte Beschreibung dieser gemischtvalenten Verbindungen verhindert. Hierfür werden neue, gut charakterisierte mehrkernige Verbindungen benötigt.

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Spectroscopic and structural investigation of the unbridged dirhodium cation [Rh2(CH3CN)10]4+

Cited by 74 publications

References 1 publication

Molecular dynamics of a grid-mounted molecular dipolar rotor in a rotating electric field

Molecular dynamics of a grid-mounted molecular dipolar rotor in a rotating electric field

Tetracyanoethylene (TCNE): The Characteristic Geometries and Vibrational Absorptions of Its Numerous Structures

Tetracyanethylen: die charakteristischen Geometrien und Schwingungsabsorptionen seiner zahlreichen Strukturen

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