Bonding, activation, and protonation of dinitrogen on a molybdenum pentaphosphine complex — Comparison to trans-bis(dinitrogen) and -nitrile – dinitrogen complexes with tetraphosphine coordination

2005 ◽  
Vol 83 (4) ◽  
pp. 385-402 ◽  
Author(s):  
Gerald C Stephan ◽  
Gerhard Peters ◽  
Nicolai Lehnert ◽  
Carsten M Habeck ◽  
Christian Näther ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Nitrogen Fixation ◽  
Analysis Procedure ◽  
Normal Coordinate Analysis ◽  
Triflic Acid ◽  
Normal Coordinate ◽  
Phosphine Complexes ◽  
Dinitrogen Complexes ◽  
Donor Acceptor ◽  
Ir And Raman

The molybdenum-N2 pentaphosphine complex [Mo(N2)(dpepp)(dppm)] (1) containing a bi- and a tridentate phosphine ligand (dpepp = PhP(CH2CH2PPh2)2, dppm = Ph2PCH2PPh2) has been prepared and characterized. By protonation of 1 with triflic acid the NNH2 complex [Mo(NNH2)(dpepp)(dppm)](CF3SO3)2 (2) is formed without loss of the pentaphosphine coordination. The electronic properties of 1 and 2 and their 15N and (or) 2H counterparts are investigated by NMR, IR, and Raman spectroscopy coupled to DFT frequency and NMR shift calculations. Force constants are evaluated from experimental frequencies and isotope shifts by the quantum chemistry based normal coordinate analysis procedure (QCB-NCA). The results for the N2 complex 1 are compared with those obtained earlier for bis(dinitrogen) and trans-nitrile dinitrogen systems. Importantly, the N2 in the pentaphosphine complex is more strongly activated compared to corresponding bis(dinitrogen) compounds and more weakly activated compared to trans-nitrile N2 systems. The activation of the NNH2 ligand in complex 2 is similar to trans-nitrile systems and weaker compared to corresponding NNH2 complexes with coordinated anions like [MoF(NNH2)(dppe)2](BF4). These results are discussed based on the relative donor–acceptor properties of the respective trans ligands, demonstrating the influence of σ donation and π acceptance on the activation of N2 in transition metal complexes.Key words: nitrogen fixation, phosphine complexes, NMR shifts, DFT calculations, normal coordinate analysis.

Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von cis-[ReCl4X2]2-, X = NCS, NCSe / Crystal Structures, Vibrational Spectra and Normal Coordinate Analysis of cis-[ReCl4X2]2-, X = NCS, NCSe

1998 ◽  
Vol 53 (11) ◽  
pp. 1329-1334 ◽  
Author(s):  
L. Homolya ◽  
S. Strueß ◽  
W. Preetz
Keyword(s):  
Crystal Structures ◽  
Normal Coordinate Analysis ◽  
X Ray Diffraction ◽  
Normal Coordinate ◽  
Triclinic Space Group ◽  
Valence Force ◽  
Space Group ◽  
X Ray ◽  
Valence Force Field ◽  
Ir And Raman

The crystal structures of cis-(n-Bu4N)2[ReCl4(NCS)2] (triclinic, space group P1̅, a = 11,245( 1), b = 20.174(3), c = 21.320(8) Å, a =109.06(2), β = 96.46(2), γ = 98.22(5)°, Z = 4) and cis-(Ph4P)2[ReCl4(NCSe)2]·2CH2Cl2 (triclinic, space group P1̅, a = 10.341(2), b = 13.436(3), c = 19.616(4) Å, α = 92.70(2), β = 92.02(2), γ = 89.99( 1)°, Z= 2) have been determined by single crystal X-ray diffraction analysis. Both ambidentate ligands NCS and NCSe are bonded via the N atom. Using the molecular parameters of the X-ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu4N) salts have been assigned by normal coordinate analysis based on a modified valence force field. The valence force constants fd(ReN) are 1,78(NCS) and 1,79(NCSe) mdyn/ Å.

Perfluormethyl-Element-Liganden, XI Die Schwingungsspektren von (CF3)2EMn(CO)5 (E=P, As) / Perfluoromethyl Element Ligands, XI. Vibrational Spectra of (CF3)2EMn(CO)5 (E = P, As)

1975 ◽  
Vol 30 (7-8) ◽  
pp. 539-543 ◽  
Author(s):  
Reinhard Demuth ◽  
Joseph Grobe ◽  
Robert Rau
Keyword(s):  
Liquid Phase ◽  
Force Field ◽  
Gas Phase ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Normal Coordinate Analysis ◽  
Ir And Raman Spectra ◽  
Normal Coordinate ◽  
Ir And Raman

The gas phase IR and liquid phase IR and Raman spectra of (CF3)2PMn(CO)5 and (CF3)2AsMn(CO)6 have been recorded. The spectra are assigned on the basis of a normal coordinate analysis using a transferred force field.

Schwingungsspektren und Normalkoordinatenanalyse von Hexathiocyanatoplatinat(IV), Kristallstruktur von [Py2CH2][Pt(SCN)6] / Vibrational Spectra and Normal Coordinate Analysis of Hexathiocyanatoplatinate(IV), Crystal Structure of [Py2CH2][Pt(SCN)6]

1998 ◽  
Vol 53 (1) ◽  
pp. 13-16
Author(s):  
J. Seemann ◽  
W. Preetz
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Low Temperature ◽  
Single Crystal ◽  
Vibrational Spectra ◽  
Structure Determination ◽  
Normal Coordinate Analysis ◽  
Normal Coordinate ◽  
X Ray ◽  
Ir And Raman

By treatment of [PtCl6]2- with an excess of SCN– in aqueous solution [Pt(SCN)6]2- is formed. The X-ray structure determination on a single crystal of [Py2CH2][Pt(SCN)6] (orthor-hombic, space group Pna21, a = 15.5084(9), b = 11.8444(11), c = 13.2830(9)Å, Z = 4) shows, that the thiocyanate groups are exclusively S-coordinated with average Pt-S distances of 2.378 Å and Pt-S-C angles in the range from 103.1° to 108.1°. Based on the molecular parameters of the X-ray determination the low temperature (10 K) IR and Raman spectra have been assigned by normal coordinate analysis. The valence force constant is fd(PtS) = 1.62 mdyn/Å.

Darstellung und Schwingungsspektren von cis- und trans-[OsXY(acac)2], X ≠ Y = Cl, Br, I sowie Normalkoordinatenanalyse von trans-[OsClBr(acac)2]/Synthesis and Vibrational Spectra of cis- and trans-[OsXY(acac)2], X ≠ Y = Cl, Br, I, and Normal Coordinate Analysis of trans-[OsClBr(acac)2]

1998 ◽  
Vol 53 (2) ◽  
pp. 227-231
Author(s):  
K. Dallmann ◽  
W. Preetz
Keyword(s):  
Normal Coordinate Analysis ◽  
Force Constants ◽  
Vibrational Modes ◽  
Normal Coordinate ◽  
Valence Force ◽  
Valence Force Field ◽  
Stretching Vibrations ◽  
Cis And Trans ◽  
Ir And Raman ◽  
Good Agreement

Abstract In the reaction of K2[OsX3 Y3] with boiling water/acetylacetone (1:1) the six mixed com­plexes cis-and trans-[OsX2 (acac)2] (X ≠ Y = Cl, Br, I) are formed, which have been purified by column chromatography with toluene on silica gel. The IR and Raman spectra (10K) show the intraligand vibrations of the acac groups with nearly constant frequencies and the stretching vibrations of OsO in the range 460-696, of OsCl at 315-345, of OsBr at 210-225, and of Osl at 160-175 cm-1 . A normal coordinate analysis based on a modified valence force field was performed for trans-[OsClBr(acac)2] and the vibrational modes have been assigned. With a set of 32 force constants, taking into account the intraligand vibrations, a good agreement between observed and calculated frequencies has been achieved. The valence force constants are fd (OsCl•) = 1.75, fd(OsBr′) = 1.63 and fd (OsO) = 3.27 mdyn/Å.

Die Schwingungsspektren der Silylanionen (SiH3)nSiH⊖3-n und (SiD3)nSiD⊖3-n / Vibrational Spectra of the Silyl Anions (SiH3)nSiH⊖3-n and (SiD3)nSiD⊖3-n

1974 ◽  
Vol 29 (9-10) ◽  
pp. 647-653 ◽  
Author(s):  
Hans Bürger ◽  
Reint Eujen
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Negative Charge ◽  
Lone Pair ◽  
Normal Coordinate Analysis ◽  
Ir And Raman Spectra ◽  
Normal Coordinate ◽  
Normal Vibrations ◽  
Stretching Vibrations ◽  
Ir And Raman

The IR and Raman spectra of SiH3⊖, SiH3SiH2⊖, (SiH3)2SiH⊖, (SiH3)3Si⊖ and their deuterated derivatives have been recorded in HMPT and HMPT-d18 solutions. Most normal vibrations have been identified. The SiH and SiSi stretching vibrations are considerably lower than for analogous silanes and silylphosphines, ∼ 2050 and 1850-1900 cm-1 being characteristic for SiH3 and SiH⊖n groups respectively. The assignments are proved by a normal coordinate analysis, and force constants have been calculated. The negative charge is mainly localized on the trivalent Si atom and the lone pair acts repulsively rather than strengthening the SiSi bond through (p→d)π effects.

Common Oxygen Binding Site in Hemocyanins from Arthropods and Mollusks. Evidence from Raman Spectroscopy and Normal Coordinate Analysis

1994 ◽  
Vol 116 (17) ◽  
pp. 7682-7691 ◽  
Author(s):  
Jinshu Ling ◽  
Lisa P. Nestor ◽  
Roman S. Czernuszewicz ◽  
Thomas G. Spiro ◽  
Robert Fraczkiewicz ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Binding Site ◽  
Normal Coordinate Analysis ◽  
Oxygen Binding ◽  
Normal Coordinate

Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der Chloro-Bromo-Technetate(IV), [TcCl„Br6_n]2-, n = 0-6 / Preparation, Vibrational Spectra and Normal Coordinate Analysis of Chloro-Bromo-Technetates(IV), [TcCln Br6-n]2-, n = 0-6

1991 ◽  
Vol 46 (11) ◽  
pp. 1496-1502 ◽  
Author(s):  
W. Preetz ◽  
A. Wendt
Keyword(s):  
Exchange Chromatography ◽  
Normal Coordinate Analysis ◽  
Exchange Reactions ◽  
Normal Coordinate ◽  
Geometrical Isomers ◽  
Valence Force ◽  
Diethylaminoethyl Cellulose ◽  
Point Groups ◽  
First Time ◽  
Ir And Raman

The mixed chloro-bromo-technetates(IV), [TcClnBr6-n2-, n = 1-5, have been separated for the first time by ion exchange chromatography on diethylaminoethyl-cellulose. Due to the stronger trans-effect of Br as compared to Cl, the ligand exchange reactions of [TcBr62- with HCl and of [TcCl6]2- with HBr proceed stereospecifically, to form either cis/fac- or trans/merspecies for n = 2, 3, 4, respectively. To avoid photoisomerization the compounds have to be handled in the absence of light. The IR and Raman spectra of the ten chloro-bromo-techne-tates(IV), including the pure geometrical isomers, have been recorded at low temperature (80 K) and completely assigned to structures of point groups Oh, D4h, C4v, C3v, and C2v, supported by normal coordinate analysis based on a general valence force field. Due to the different trans-influences Cl < Br in asymmetric Cl′—Tc— Br′ axes, the Tc— Br′ bonds are strengthened and the Tc—Cl′ bonds are weakened, as indicated by valence force constants, for Tc—Br′ on average 6% higher and for Tc—Cl′ 10% lower, as compared with the values calculated for symmetric Br—Tc—Br and CI—Tc—Cl axes, respectively.

Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von cis- und trans-[ReCl4 (NCSe)(SeCN)]2- / Crystal Structures, Vibrational Spectra, and Normal Coordinate Analysis of cis- and trans-[ReCl4 (NCSe)(SeCN)]2-

1999 ◽  
Vol 54 (3) ◽  
pp. 357-362 ◽  
Author(s):  
S. Strueß ◽  
W. Preetz
Keyword(s):  
Low Temperature ◽  
Crystal Structures ◽  
Normal Coordinate Analysis ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Normal Coordinate ◽  
Space Group ◽  
X Ray ◽  
Cis And Trans ◽  
Ir And Raman

The crystal structures of cis-(n-Bu4N)2[ReCl4(NCSe)(SeCN)] (monoclinic, space group P21/n a = 10.794(3), b = 11.687(3), c = 35.716(4) Å, β = 96.97(1)°, Z = 4) and trans- (CH2Py2)[ReCl4(NCSe)(SeCN)] (monoclinic, space group P21/c, a = 8.348(2), b = 7.518(1), c - 31.295(7) Å, ß = 97.12(2)°, Z = 4) have been determined by single crystal X-ray diffraction analysis. Based on the molecular parameters of the X-ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu4N) salts have been assigned by normal coordinate analysis. The valence force constants are fd(ReN) = 1.68 and fd(ReSe) =1.15 mdyn/Å.

Sign in / Sign up

Export Citation Format

Share Document