Double bond rule

Double bond rule

The double bond rule states that chemical elements with a principal quantum number greater than 2 (e.g. Period 3 elements and lower) do not form multiple bonds (e.g. double bonds and triple bonds) with themselves or with other elements.[1] The double bonds if they exist are weak due to weak pi bonds as a results of poor orbital overlap.

This rule was challenged and ultimately made obsolete starting from 1981 with the discovery of silicon and phosphorus double bonds.[2] Double bonds that would ordinarily not form can be stabilized with proper functional groups either electronically or sterically (kinetic stabilization).


Double bonds for carbon and nearest neighbours
boron carbon nitrogen oxygen silicon phosphorus sulfur
boron diborenes alkylideneboranes aminoboranylidenes rare [3] oxoboranes rare,
rapid oligomerization [4]
not known boranylidenephosphanes,
rare, stable compounds are known [5]
thioxoboranes , rare [6]
carbon alkenes imines carbonyls , oxonium ions silenes phosphaalkenes thioketones
nitrogen Azo compounds nitroso compounds silanimines, rare
easy oligomerization, only at low temp. [7]
phosphazene sulfilimines
oxygen dioxygen Silanones Si=O bonds do not form
oligomerisation to siloxane,
only fleeting evidence [8] [9]
Numerous, e.g. phosphine oxides ,
phosphonates,
Phosphinates,
phosphates
sulfinyls
silicon disilenes Silylidenephosphanes
a.k.a. phosphasilenes
rare [10]
silanethiones , rare
easy oligomerization [11]
phosphorus diphosphenes Common, for example in thiophosphates
and in phosphine sulfides for example triphenylphosphine sulfide,
certain dithiadiphosphetanes
sulfur disulfur, thiosulfoxides


References

  1. ^ New Element-Carbon (p-p) Bonds Doz. Dr. Peter Jutzi Angewandte Chemie International Edition in English Volume 14 Issue 4, Pages 232 - 245 1975 doi:10.1002/anie.197502321
  2. ^ Multiple bonds to silicon: 20 years later Robert West Polyhedron Volume 21, Issues 5-6, 15 March 2002, Pages 467-472 doi:10.1016/S0277-5387(01)01017-8
  3. ^ some research efforts exists in isomerization of B=NH2 to triple bonded iminoborane HBNH The aminoboranylidene–iminoborane isomerization Victor M. Rosas-Garcia and T. Daniel Crawford J. Chem. Phys, 119, 10647 2003
  4. ^ Synthesis and Characterization of a Coordinated Oxoborane: Lewis Acid Stabilization of a Boron-Oxygen Double Bond Dragoslav Vidovic, Jennifer A. Moore, Jamie N. Jones, and Alan H. Cowley J. Am. Chem. Soc., 2005, 127 (13), 4566-4567 doi:10.1021/ja0507564
  5. ^ For instance Ar*P=B(TMP)2 with TMP = 2,2,6,6-Tetramethylpiperidine and Ar* = 2,6-dimesityl-phenyl Boron-Pnictogen Multiple Bonds: Donor-Stabilized PdB and AsdB Bonds and a Hindered Iminoborane with a B-N Triple Bond Eric Rivard, W. Alexander Merrill, James C. Fettinger, Robert Wolf, Geoffrey H. Spikes, and Philip P. Power Inorg. Chem. 2007, 46, 2971-2978 doi:10.1021/ic062076n
  6. ^ Formation and Reactions of a Thioxoborane, a Novel Boron--Sulfur Double-bond Compound Norihiro Tokitoh, Mitsuhiro Ito, and Renji Okazaki Tetrahedron Letters, Vol. 37, No. 29, pp. 5145-5148, 1996
  7. ^ Observation of a silanimine in an inert matrix and in solution at low temperature Steven S. Zigler, Robert West and Josef Michl Chemistry Letters Vol.15 , No.6(1986)pp.1025-1028 doi:10.1246/cl.1986.1025
  8. ^ On the proposed thermal interconversion of matrix-isolated dimethylsilylene and 1-methylsilene: their reactions with oxygen atom donors Charles A. Arrington, Robert West, Josef Michl J. Am. Chem. Soc., 1983, 105 (19), pp 6176–6177 doi:10.1021/ja00357a048
  9. ^ Infrared spectroscopic evidence for silicon-oxygen double bonds: silanone and the silanoic and silicic acid molecules Robert Withnall, Lester Andrews J. Am. Chem. Soc., 1985, 107 (8), pp 2567–2568 doi:10.1021/ja00294a070
  10. ^ Example Ar*tBuSi=PAr* with Ar* 2,4,6-trisiopropylphenyl and tBu tert-butyl in Ungewohnliche Reaktivitat der Silicium-Phosphor-Doppelbindung in einem Silyliden(fluorsilyl)phosphan: intramolekulare C,H-Inserierung und seine Umwandlung in ein neues Silyliden(silyl)phosphan M. Driess, S. Rell und K. Merz Z. Anorg. Allg. Chem. 1999, 625, 1119±1123
  11. ^ The First Genuine Silicon-Sulfur Double-Bond Compound: Synthesis and Crystal Structure of a Kinetically Stabilized Silanethione Hiroyuki Suzuki, Norihiro Tokitoh, Shigeru Nagase, Renji Okazaki J. Am. Chem. Soc., 1994, 116 (25), pp 11578–11579 doi:10.1021/ja00104a052

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