Neutron diffraction study on a single crystal of pentacarbonyldiethylcyanamidechromium at 110 K

Ohnet, Marie-Noëlle; Biré, Anne Spasojevic - de; Dao, Nguyen Quy; Schweiß, P.; Braden, M.; Fischer, Helmut; Reindl, David

doi:10.1039/dt9950000665

Cited by 11 publications

(5 citation statements)

References 67 publications

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“…43 The most remarkable feature of W(P i Pr 3 ) 2 (CO) 3 -(Me 2 NCN) is that the amide N exhibits trigonal planar geometry. This behavior has been previously reported for other complexes such as Cr(CO) 5 (NCNEt 2 ), 44 trans-[Fe- 45 and trans-Mo-(Ph 2 PCH 2 CH 2 PPh 2 ) 2 (NCNEt 2 )(N 2 ). 46 This geometric preference for trigonal planar geometry of the amide is attributed to delocalization of the amide lone pair of electrons and significant contribution of the sp 2 hybridized N resonance form as shown in reaction 12.…”

Section: Resultssupporting

confidence: 85%

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR₃)₂(CO)₃ (M = Mo, W; R = Me, ⁱPr).

et al. 2009

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The enthalpies of binding of a number of N-donor ligands to the complex Mo(P(i)Pr(3))(2)(CO)(3) in toluene have been determined by solution calorimetry and equilibrium measurements. The measured binding enthalpies span a range of approximately 10 kcal mol(-1): DeltaH(binding) = -8.8 +/- 1.2 (N(2)-Mo(P(i)Pr(3))(2)(CO)(3)); -10.3 +/- 0.8 (N(2)); -11.2 +/- 0.4 (AdN(3) (Ad = 1-adamantyl)); -13.8 +/- 0.5 (N(2)CHSiMe(3)); -14.9 +/- 0.9 (pyrazine = pz); -14.8 +/- 0.6 (2,6-Me(2)pz); -15.5 +/- 1.8 (Me(2)NCN); -16.6 +/- 0.4 (CH(3)CN); -17.0 +/- 0.4 (pyridine); -17.5 +/- 0.8 ([4-CH(3)pz][PF(6)] (in tetrahydrofuran)); -17.6 +/- 0.4 (C(6)H(5)CN); -18.6 +/- 1.8 (N(2)CHC( horizontal lineO)OEt); and -19.3 +/- 2.5 kcal mol(-1) (pz)Mo(P(i)Pr(3))(2)(CO)(3)). The value for the isonitrile AdNC (-29.0 +/- 0.3) is 12.3 kcal mol(-1) more exothermic than that of the nitrile AdCN (-16.7 +/- 0.6 kcal mol(-1)). The enthalpies of binding of a range of arene nitrile ligands were also studied, and remarkably, most nitrile complexes were clustered within a 1 kcal mol(-1) range despite dramatic color changes and variation of nu(CN). Computed structural and spectroscopic parameters for the complexes Mo(P(i)Pr(3))(2)(CO)(3)L are in good agreement with experimental data. Computed binding enthalpies for Mo(P(i)Pr(3))(2)(CO)(3)L exhibit considerable scatter and are generally smaller compared to the experimental values, but relative agreement is reasonable. Computed enthalpies of binding using a larger basis set for Mo(PMe(3))(2)(CO)(3)L show a better fit to experimental data than that for Mo(P(i)Pr(3))(2)(CO)(3)L using a smaller basis set. Crystal structures of Mo(P(i)Pr(3))(2)(CO)(3)(AdCN), W(P(i)Pr(3))(2)(CO)(3)(Me(2)NCN), W(P(i)Pr(3))(2)(CO)(3)(2,6-F(2)C(6)H(3)CN), W(P(i)Pr(3))(2)(CO)(3)(2,4,6-Me(3)C(6)H(2)CN), W(P(i)Pr(3))(2)(CO)(3)(2,6-Me(2)pz), W(P(i)Pr(3))(2)(CO)(3)(AdCN), Mo(P(i)Pr(3))(2)(CO)(3)(AdNC), and W(P(i)Pr(3))(2)(CO)(3)(AdNC) are reported.

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Section: Resultssupporting

confidence: 85%

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR₃)₂(CO)₃ (M = Mo, W; R = Me, ⁱPr).

et al. 2009

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Section: Resultssupporting

confidence: 82%

“…The amide N exhibits trigonal planar geometry in 1-[NCNMe 2 ] for both η 1 and η 2 conformers. This behavior has been previously reported for other complexes such as trans-[Mo(N 2 )(NCNEt 2 )(dppe) 2 ], 15 W(P[ i Pr] 3 ) 2 (CO) 3 (Me 2 -NCN), 16 Cr(CO) 5 (NCNEt 2 ), 37 38 DFT calculations at the BP86/6-311G(d,p) (MWB28 with an additional set of f functions for Mo) level predict a ∆E 0 ) -16.3 kcal mol -1 for formation of 1-[η 1 -NCPh] which compares to the experimentally determined value of ∆H ) -14.5 ( 1.5 kcal mol -1 . For the formation of 1-[η 2 -NCPh], ∆E 0 ) -10.3 kcal mol -1 , implying that for PhCN the η 2 binding motif is less stable than is the η 1 .…”

Section: Computational Analysis Of Binding Of Phcn and Me 2 Ncn As Bo...supporting

confidence: 84%

Coordination-Mode Control of Bound Nitrile Radical Complex Reactivity: Intercepting End-on Nitrile−Mo(III) Radicals at Low Temperature

et al. 2009

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Variable temperature equilibrium studies were used to derive thermodynamic data for formation of eta(1) nitrile complexes with Mo(N[(t)Bu]Ar)(3), 1. (1-AdamantylCN = AdCN: DeltaH(degrees) = -6 +/- 2 kcal mol(-1), DeltaS(degrees) = -20 +/- 7 cal mol(-1) K(-1). C(6)H(5)CN = PhCN: DeltaH(degrees) = -14.5 +/- 1.5 kcal mol(-1), DeltaS(degrees) = -40 +/- 5 cal mol(-1) K(-1). 2,4,6-(H(3)C)(3)C(6)H(2)CN = MesCN: DeltaH(degrees) = -15.4 +/- 1.5 kcal mol(-1), DeltaS(degrees) = -52 +/- 5 cal mol(-1) K(-1).) Solution calorimetric studies show that the enthalpy of formation of 1-[eta(2)-NCNMe(2)] is more exothermic (DeltaH(degrees) = -22.0 +/- 1.0 kcal mol(-1)). Rate and activation parameters for eta(1) binding of nitriles were measured by stopped flow kinetic studies (AdCN: DeltaH(on)(++) = 5 +/- 1 kcal mol(-1), DeltaS(on)(++) = -28 +/- 5 cal mol(-1) K(-1); PhCN: DeltaH(on)(++) = 5.2 +/- 0.2 kcal mol(-1), DeltaS(on)(++) = -24 +/- 1 cal mol(-1) K(-1); MesCN: DeltaH(on)(++) = 5.0 +/- 0.3 kcal mol(-1), DeltaS(on)(++) = -26 +/- 1 cal mol(-1) K(-1)). Binding of Me(2)NCN was observed to proceed by reversible formation of an intermediate complex 1-[eta(1)-NCNMe(2)] which subsequently forms 1-[eta(2)-NCNMe(2)]: DeltaH(++)(k1) = 6.4 +/- 0.4 kcal mol(-1), DeltaS(++)(k1) = -18 +/- 2 cal mol(-1) K(-1), and DeltaH(++)(k2) = 11.1 +/- 0.2 kcal mol(-1), DeltaS(++)(k2) = -7.5 +/- 0.8 cal mol(-1) K(-1). The oxidative addition of PhSSPh to 1-[eta(1)-NCPh] is a rapid second-order process with activation parameters: DeltaH(++) = 6.7 +/- 0.6 kcal mol(-1), DeltaS(++) = -27 +/- 4 cal mol(-1) K(-1). The oxidative addition of PhSSPh to 1-[eta(2)-NCNMe(2)] also followed a second-order rate law but was much slower: DeltaH(++) = 12.2 +/- 1.5 kcal mol(-1) and DeltaS(++) = -25.4 +/- 5.0 cal mol(-1) K(-1). The crystal structure of 1-[eta(1)-NC(SPh)NMe(2)] is reported. Trapping of in situ generated 1-[eta(1)-NCNMe(2)] by PhSSPh was successful at low temperatures (-80 to -40 degrees C) as studied by stopped flow methods. If 1-[eta(1)-NCNMe(2)] is not intercepted before isomerization to 1-[eta(2)-NCNMe(2)] no oxidative addition occurs at low temperatures. The structures of key intermediates have been studied by density functional theory, confirming partial radical character of the carbon atom in eta(1)-bound nitriles. A complete reaction profile for reversible ligand binding, eta(1) to eta(2) isomerization, and oxidative addition of PhSSPh has been assembled and gives a clear picture of ligand reactivity as a function of hapticity in this system.

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“…The trigonal planar geometry has also been reported for other complexes such as [Cr(NCNEt 2 )(CO) 5 ], trans -[Fe(NCNEt 2 ) 2 (depe) 2 ][BF 4 ] 2 (depe = Et 2 PCH 2 CH 2 PEt 2 ), trans -[Pt(CF 3 )(NCNEt 2 )(PPh 3 ) 2 ][BF 4 ], or cis -[Pt(NCNEt 2 ) 2 (PPh 3 ) 2 ][BF 4 ] 2 , whereas the pyramidal one is displayed by mer -[ReCl 2 (NCNEt 2 )(PMePh 2 ) 3 ] and by the uncoordinated NCNMe 2 …”

Section: Resultssupporting

confidence: 52%

Mixed Dinitrogen−Organocyanamide Complexes of Molybdenum(0) and Their Protic Conversion into Hydrazide and Amidoazavinylidene Derivatives

Cunha¹,

Silva²,

Pombeiro³

2003

Inorg. Chem.

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Organocyanamides, Ntbd1;CNR(2) (R = Me or Et), react with trans-[Mo(N(2))(2)(dppe)(2)] (1, dppe = Ph(2)PCH(2)CH(2)PPh(2)), in THF, to give the first mixed molybdenum dinitrogen-cyanamide complexes trans-[Mo(N(2))(NCNR(2))(dppe)(2)] (R = Me 2a or Et 2b) which are selectively protonated at N(2) by HBF(4) to yield the hydrazide(2-) complexes trans-[Mo(NNH(2))(NCNR(2))(dppe)(2)][BF(4)](2) (R = Me, 3a, or Et, 3b). On treatment with Ag[BF(4)], oxidation and metal fluorination occur, and the ligating cyanamide undergoes an unprecedented beta-protonation at the unsaturated C atom to form trans-[MoF(NCHNR(2))(dppe)(2)][BF(4)](2) (R = Me, 4a, or Et, 4b) compounds which present the novel amidoazavinylidene (or amidomethyleneamide) ligands. Complexes 4 are also formed from the corresponding compounds 3, with liberation of ammonia and hydrazine. The crystal structure of 2b was determined by single-crystal X-ray diffraction analysis which indicates that the N atom of the amide group has a trigonal planar geometry.

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Neutron diffraction study on a single crystal of pentacarbonyldiethylcyanamidechromium at 110 K

Cited by 11 publications

References 67 publications

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR₃)₂(CO)₃ (M = Mo, W; R = Me, ⁱPr).

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR₃)₂(CO)₃ (M = Mo, W; R = Me, ⁱPr).

Coordination-Mode Control of Bound Nitrile Radical Complex Reactivity: Intercepting End-on Nitrile−Mo(III) Radicals at Low Temperature

Mixed Dinitrogen−Organocyanamide Complexes of Molybdenum(0) and Their Protic Conversion into Hydrazide and Amidoazavinylidene Derivatives

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Neutron diffraction study on a single crystal of pentacarbonyldiethylcyanamidechromium at 110 K

Cited by 11 publications

References 67 publications

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR3)2(CO)3 (M = Mo, W; R = Me, iPr).

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR3)2(CO)3 (M = Mo, W; R = Me, iPr).

Coordination-Mode Control of Bound Nitrile Radical Complex Reactivity: Intercepting End-on Nitrile−Mo(III) Radicals at Low Temperature

Mixed Dinitrogen−Organocyanamide Complexes of Molybdenum(0) and Their Protic Conversion into Hydrazide and Amidoazavinylidene Derivatives

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Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR₃)₂(CO)₃ (M = Mo, W; R = Me, ⁱPr).

Experimental and Computational Studies of Binding of Dinitrogen, Nitriles, Azides, Diazoalkanes, Pyridine, and Pyrazines to M(PR₃)₂(CO)₃ (M = Mo, W; R = Me, ⁱPr).