The molecular structures of dicyclopentadienylvanadium, (C5H5)2V, and dicyclopentadienylchromium, (C5H5)2Cr, determined by gas phase electron diffraction

Gard, Ellen; Haaland, Arne; Novak, David P.; Seip, Ragnhild

doi:10.1016/s0022-328x(00)91459-1

Cited by 86 publications

(29 citation statements)

References 11 publications

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“…The Cr-C(ring) distances are identical within standard deviations; their mean value of 216 ± 1 pm is in close agreement with a value of 216.9(0.4) pm observed for (CsHshCr by gas phase electron diffraction [8]. The centroid-metal-centroid angle is 143.3°, substantially larger than the angles of 128 and 130° observed in ethylene- Cr-C(I) 217(1) Cr-C(6) 214(1) Cr-C (2) 216(1) Cr-C(7) 217(1) Cr-C 3214 1Cr-C(8) 218(1) Cr-C 4216 1Cr-C(9) 213(1) Cr-C (5) 218 ( bridged [9) and in unbridged titanocene dichloride [10), but quite close to a centroid-metal-centroid angle of 145.8 0 observed for (CsHshMoH2 [11].…”

Section: Resultssupporting

confidence: 86%

ansa-metallocene derivatives

Schwemlein

Zsolnai

Hüttner

et al. 1983

Journal of Organometallic Chemistry

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The tetramethylethylene-bridged chromocene carbonyl complex (CH 3)4-C2(CsH4hCr(CO) is obtained by reaction of the Grigt\ard compound (CH 3 k C2(CsH4MgClh•4THF with CrC1 2 • THF under CO. The diamagnetic carbonyl complex is the first thermally stable chromocene ligand adduct; its structure is that of a normal wedge-shaped metallocene derivative whose ring ligands span a centroid-chromium-centroid angle of 143°; the molecule closely approximates to C 2 symmetry with respect to the Cr-C=O axis.

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Section: Resultssupporting

confidence: 86%

ansa-metallocene derivatives

Schwemlein

Zsolnai

Hüttner

et al. 1983

Journal of Organometallic Chemistry

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“…23b However, while the appropriate, average M-C distances in M(2,4-C 7 H 11 ) 2 and M(C 8 H 11 ) 2 complexes are similar to those of chromocene and ferrocene, those for the low spin complexes 1 and 2 are much shorter than in metallocenes of vanadium (2.199 vs. 2.280 Å) and titanium (2.245 vs. 2.352 Å). 12, 27 Although it is clear that spin configurations can have a large effect on bond distances, such that comparably stable species may have much differing bond distances (e.g., manganocenes 28 ), structural data for half-open metallocenes of titanium, 2a vanadium, 29 even chromium 30 and more recently zirconium 31 have demonstrated that such differences persist even when the two ligands are present in the same complex, and hence are no longer subject to spin state differences. Theoretical calculations have substantiated expectations of stronger bonding for the pentadienyl ligand, and have revealed that the open ligands engender a much greater degree of metalligand orbital mixing, and furthermore generally serve as much stronger electron acceptors, through a significant δ interaction.…”

Section: Structuralmentioning

confidence: 99%

Syntheses and characterization of the edge-bridged open metallocenes M(C8H11)2 (C8H11 = cyclooctadienyl; M = Ti, V, Cr or Fe) †

Kulsomphob¹,

Tomaszewski²,

Yap³

et al. 1999

J. Chem. Soc., Dalton Trans.

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The reactions of two equivalents of the cyclooctadienyl anion with various divalent transition metal salts (M = Ti, V, Cr or Fe) led to the formation of the appropriate bis(cyclooctadienyl)metal complexes, isolable as crystalline compounds. Their constitutions have been established through NMR and mass spectroscopies, elemental analyses, and single crystal X-ray diffraction studies. As with the M(2,4-C 7 H 11 ) 2 and M(6,6-dmch) 2 (C 7 H 11 = dimethylpentadienyl; dmch = dimethylcyclohexadienyl) complexes, the titanium and vanadium compounds adopt low spin configurations, thereby differing from their metallocene analogs. The structures observed for these complexes in the solid state are similar to those of the M(2,4-C 7 H 11 ) 2 complexes. The low spin titanium complex also forms a mono(ligand) adduct with CO, although the binding appears noticeably weak due to the steric influence of the edge bridge.

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“…(d) Parameters adjusted for the effects of thermal motion are given in parentheses. * References (ED: electron diffraction): (1) Gard, Haaland, Novak & Seip (1975); (2) Almenningen, Haaland & Motzfeldt (1967); (3) Freyberg, Robbins, Raymond & Smart (1979); (4) Haaland & Nilsson (1968); (5) Seiler & Dunitz (1979a,b); (6) Almenningen, Gard & Haaland (1976); (7) Bfinder & Weiss (1975); (8) Hedberg & Hedberg (1970); (9) Seller & Dunitz (1980); (10) Tuggle & Weaver (1971); (11) Siebert, Bochmann, Edwin, Kriiger & Tsay (1978); (12) this paper; (13) Beer et al (1973); (14) Pipal & Grimes (1978); (15) Siebert, Renk, Kinberger, Bochmann & Krfiger (1976); (16) Siebert, B6hle & Kriiger (1980 (Fig. 4) with an approximate transition enthalpy of 0.12 kJ mo1-1 was detected.…”

Section: Comparison Of the Two Structuresmentioning

confidence: 99%