메뉴 건너뛰기




Volumn 761, Issue 1-3, 2006, Pages 177-193

Understanding ring strain and ring flexibility in six- and eight-membered cyclic organometallic group 14 oxides

Author keywords

cyclo Germoxanes; cyclo Siloxanes; cyclo Stannasiloxanes; cyclo Stannoxanes; DFT calculations; Ring strain

Indexed keywords


EID: 33645416541     PISSN: 01661280     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.theochem.2006.01.003     Document Type: Article
Times cited : (17)

References (140)
  • 15
    • 0003863877 scopus 로고
    • Academic Press New York
    • When the substituents on silicon are sufficiently small, the ring-opening activation energy of the cyclo-trisiloxanes is lower than those of the larger siloxane rings, as the silicon atoms in the cyclo-trisiloxanes are rigidly held in a geometric configuration that closely resembles the transition-state geometry and favours attack by the catalyst. For reviews see W. Noll Chemistry and Technology of the Silicones 1968 Academic Press New York
    • (1968) Chemistry and Technology of the Silicones
    • Noll, W.1
  • 17
    • 0004211893 scopus 로고
    • J.A. Semlyen S.J. Clarson Prentice-Hall Englewood Cliffs, NJ
    • E.E. Bostick J.A. Semlyen S.J. Clarson Siloxane Polymers 1991 Prentice-Hall Englewood Cliffs, NJ
    • (1991) Siloxane Polymers
    • Bostick, E.E.1
  • 26
    • 33645384794 scopus 로고    scopus 로고
    • note
    • 4 (Ref. [14d]).
  • 37
    • 33645414210 scopus 로고    scopus 로고
    • See Ref. [15b].
    • n of unknown molecular weight. See Ref. [15b].
  • 38
    • 33645410845 scopus 로고    scopus 로고
    • See Ref. [15a].
    • nOH. See Ref. [15a].
  • 39
    • 33645379790 scopus 로고    scopus 로고
    • See Ref. [2].
    • 3 is presumed to rearrange instantly into larger rings and polymers even below room temperature. See Ref. [2].
  • 74
    • 33645403521 scopus 로고    scopus 로고
    • F.H. Westheimer, Special Publication No. 8, The Royal Chemical Society, 1957.
    • F.H. Westheimer, Special Publication No. 8, The Royal Chemical Society, 1957.
  • 75
    • 33645383408 scopus 로고    scopus 로고
    • note
    • 2O, consists of two Sn-O-Si angles, one Si-O-Si angle, two O-Si-O angles and one O-Sn-O angle.
  • 76
    • 0003422992 scopus 로고    scopus 로고
    • second ed. Gaussian Inc. Pittsburgh, PA
    • A normal PES scan calculation samples points on the PES by performing single-point calculations at various structures. A relaxed PES scan calculation similarly samples points on the PES, however, the remaining 'non-scanned' geometric parameters are optimized at each point. See J.B. Foresman, and A.E. Frisch Exploring Chemistry with Electronic Structure Methods second ed. 1996 Gaussian Inc. Pittsburgh, PA p. 171
    • (1996) Exploring Chemistry with Electronic Structure Methods
    • Foresman, J.B.1    Frisch, A.E.2
  • 87
    • 33645401196 scopus 로고    scopus 로고
    • note
    • The Microsoft Excel Solver uses the Generalized Reduced Gradient (GRG2) nonlinear optimization code developed by L. Lasdon, University of Texas at Austin, and A. Waren, Cleveland State University. Linear and integer problems use the simplex method with bounds on the variables, and the branch-and-bound method, implemented by J. Watson and D. Fylstra, Frontline Systems, Inc. Portions of the Mircosoft Excel Solver program code are copyright 1990, 1991, 1992, and 1995 by Frontline Systems, Inc. Portions are copyright (1989) by Optimal Methods, Inc.
  • 90
    • 33751156292 scopus 로고
    • Extensive computational studies of the siloxane potential energy surface have previously shown that disiloxane is extremely difficult to model accurately: the inclusion of electron correlation effects and the use of large basis sets possessing f polarization functions are necessary to obtain reasonably accurate results. See J. Koput J. Phys. Chem. 99 1995 15874
    • (1995) J. Phys. Chem. , vol.99 , pp. 15874
    • Koput, J.1
  • 93
    • 33645381806 scopus 로고    scopus 로고
    • See Ref. [36].
    • Ge-O-Ge(eq)] in digermoxane is calculated to be 138.2° at the HF/6-311++G(2d,2p) level of theory. See Ref. [36]. Therefore, our obtained agreement with experiment is pleasing and justifies the semi-quantitative use of our results in this paper.
  • 99
    • 0000186149 scopus 로고
    • 3 (see Ref. [56b]), the X-ray structures of many open-chain siloxanes suggest the presence of linear Si-O-Si angles. Most of these compounds possess abnormally short Si-O bond lengths and crystallize in centrosymmetric space groups, in which the oxygen atoms lie across crystallographic centers of inversion. The majority of these cases can be considered to be crystallographic artifacts. Thus, linear Si-O-Si linkages need to be interpreted with caution. See C. Glidewell, and D.C. Liles J. Organomet. Chem. 212 1981 291
    • (1981) J. Organomet. Chem. , vol.212 , pp. 291
    • Glidewell, C.1    Liles, D.C.2
  • 105
    • 33645413974 scopus 로고    scopus 로고
    • note
    • -1.
  • 106
    • 33645399851 scopus 로고    scopus 로고
    • See Ref. [52a and b].
    • A significant feature of the M-O-M′ bending PESs described here is that they are shallow potentials, and previous studies have indicated that the location of the minima in such shallow potentials can be very sensitive to the method of calculation. See Ref. [52a and b].
  • 107
    • 33645423255 scopus 로고    scopus 로고
    • (See Ref. [52a]).
    • Comparisons of the calculated results with experimental geometries are made throughout the paper. It is important to emphasize that experimentally obtained geometric parameters are vibrationally averaged values, and the effects of such averaging can be substantial (See Ref. [52a]). If quantitative comparisons were required for these systems, it would formally be more appropriate to compare calculated vibrationally averaged angles with the experimental angles. Nevertheless, the non-vibrationally averaged angles reported herein correctly reproduce the experimentally observed ordering in angle size and may be applied in a qualitative study.
  • 112
    • 0006975713 scopus 로고
    • The origin of this periodic anomaly is the increased attraction for electrons by the germanium nucleus, which is poorly shielded by the filled 3d orbitals. See J.E. Huheey, and C.L. Huheey J. Chem. Educ. 49 1972 227
    • (1972) J. Chem. Educ. , vol.49 , pp. 227
    • Huheey, J.E.1    Huheey, C.L.2
  • 114
    • 33645418947 scopus 로고    scopus 로고
    • note
    • -1.
  • 116
    • 33645397757 scopus 로고    scopus 로고
    • note
    • Procedure B, which only accounts for the total angular contribution to ring strain, results in strain energies that are consistently lower than those obtained using group-equivalent reactions (see Supporting Information). However, the trend observed using the group-equivalent reactions is correctly reproduced.
  • 128
    • 33645398912 scopus 로고    scopus 로고
    • note
    • Geometric parameters were taken from the CCDC database.
  • 129
    • 33645415346 scopus 로고    scopus 로고
    • PhD thesis, Dortmund University
    • 2O are unsuitable for ROPs. See J. Beckmann, PhD thesis, Dortmund University, 1999.
    • (1999)
    • Beckmann, J.1
  • 131
    • 33645384121 scopus 로고    scopus 로고
    • note
    • In principle, the endocyclic angles of a strain-free ring calculated using Procedure B should exactly match the equilibrium angles of the corresponding model compounds. However, the use of fitted potential functions results in strain-free endocyclic angles that vary slightly (<0.5°) from the model equilibrium angles.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.