Bending, triple bonds

As a result of complex formation, the normally linear digonally hybridized triple bond bends to approximately 145°. Two 7i-bonds in the triple bond coordinate to two Co atoms, respectively, as shown by 130. In the following discussion, the simplified form 131 is used instead of 130 in most cases for simplicity. 

Triple bond, bending, 205 Triplet, 12, 14, 180 impure, 28. 220-21, 227 Triplet energy of sensitizer, 372, 407 Triplet function, 222 Triplet state, aromatics, 76 calculation, 55 ethylene, 64... 

Stearic acid is a saturated fatty acid. This means it has only single bonds between its carbon atoms. This means it can coil up and form into random shapes. Double bonds between carbon atoms restrict the bending of the molecule at the point of the bond, like a hinge that lets a door swing back and forth but not up and down. Triple bonds are even more restrictive, locking the joint in place three-dimensionally, like the legs of a tripod. 

A complexation-initiated reaction was realized for the first time as depicted below. Thus, the octacarbonyldicobalt complex of furan is subjected to silica gel and gives rise to the adduct with a seven-membered ring owing to bending of the triple bond to a structure with an angle of around 140° when the alkyne is allowed to react with Co2(CO)8 at room temperature . 

Hexafluorobutyne-2 will add to platinum(II) complexes. The insoluble complex PtMe HB(pz)3 reacts with dissolution and the five-coordinate alkyne complexes can be isolated (equation 269).815 The coordination about platinum(II) is essentially trigonal bipyrami-dal. The C C triple bond is lengthened on coordination to 1.292(12) A and the alkyne bend-back angle is 34.4(4)°.816 These complexes have a -bonded alkyne ligand, and show different structural and reaction chemistry than platinum(II) acetylide complexes.817-821... 

From a simple point of view one would expect that in plane eis-bending at the triple bond would lead to less efficient overlap in the in plane rc-bond, while the ic-bond perpendicular to this plane would not be affected very much by in plane bending. However, substantial a-n-mixing must necessarily occur as a consequence of angle bending. 

Thus, O2 fits neatly into the above series, in which the bond order steadily decreases from 3 to 1 due to successive addition of antibonding wr orbitals to the system. The bond order can be conveniently regarded as X (number of bonding electrons—number of antibonding electrons) thus N2 has a triple bond, F2 has a single bond, and NO has a two-and-one-half bend. As with the resonance interpretation, an odd electron does not belong to either atom alone, but is spread over the entire mokifeule. 

In this chapter, we review the progress we have made to date, and describe the issues that need to be addressed by further studies. The chapter is divided into three parts. The first deals with the ultrafast internal conversion of photoexcited nucleobases, and the role the out-of-plane deformation (twisting of a double bond, leading to biradicaloid geometry) plays in the photoprocess. The second is concerned with the highly efficient ICT process in dialkylaminobenzonitriles and related EDA molecules, where in-plane bending of the triple bond (which yields ira state of... 

It s not possible to form a small ring containing a triple bond because the angle strain that would result from bending the bonds of an jp-hybridized carbon to form a small ring is too great. 

A complexation-induced intramolecular Diels-Alder cycloaddition of furan is depicted in Scheme 34. Upon exposure to silica gel, the alkyne-Co2(CO)6 complex 61 was transformed to the cycloadduct that contained a seven-membered ring <20000L871>. This facile process was supposed to be arisen from the bending of the linear triple bond to a structure with a 140° angle between the two carbon substituents in the cobalt complex 61. 

---