Boron monofluoride
Encyclopedia
boron monofluoride or fluoroborylene is a chemical compound with formula BF, one atom of boron
and one of fluorine
. It was discovered as an unstable gas and only in 2009 found to be a stable ligand
combining with transition metal
s, in the same way as carbon monoxide
. It is a subhalide, containing fewer than the normal number of fluorine atoms, compared with boron trifluoride
. BF is isoelectronic with carbon monoxide and dinitrogen.
is 1.263 angstrom
. One reported computed bond order
for the molecule is 1.4.
gas at 2000 °C over a boron rod. It can be condensed at liquid nitrogen temperatures (-196°).
to form B2F4
. BF and B2F4 further combine to form B3F5. B3F5 is unstable above -50° and forms B8F12. This substance is a yellow oil.
BF reacts with acetylenes to make the 1,4-diboracyclohexadiene ring system.
BF can condense with 2-butyne forming 1,4-difluoro-2,3,5,6-tetramethyl-1,4-diboracyclohexadiene.
Also it reacts with acetylene
to make 1,4-difluoro-1,4-diboracyclohexadiene.
on a transition element was demonstrated in 2009 with the compound (C5H5)2Ru2(CO)4(μ-BF). The BF was bound to both ruthenium
atoms as a bridge. Vidovic
and Aldridge reacted NaRu(CO)2(C5H5) with (Et2O):BF3. Note that the BF was formed in place rather than added on.
Earlier in 1968 K. Kämpfer, H. Nöth, W. Petz, and G. Schmid claimed that Fe(BF)(CO)4 was formed in the reaction of B2F4 with Fe(CO)5
, however this has not been reproduced.
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
and one of fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
. It was discovered as an unstable gas and only in 2009 found to be a stable ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
combining with transition metal
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...
s, in the same way as carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
. It is a subhalide, containing fewer than the normal number of fluorine atoms, compared with boron trifluoride
Boron trifluoride
Boron trifluoride is the chemical compound with the formula BF3. This pungent colourless toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.-Structure and bonding:...
. BF is isoelectronic with carbon monoxide and dinitrogen.
Structure
The experimental B-F bond lengthBond length
- Explanation :Bond length is related to bond order, when more electrons participate in bond formation the bond will get shorter. Bond length is also inversely related to bond strength and the bond dissociation energy, as a stronger bond will be shorter...
is 1.263 angstrom
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
. One reported computed bond order
Bond order
Bond order is the number of chemical bonds between a pair of atoms. For example, in diatomic nitrogen N≡N the bond order is 3, while in acetylene H−C≡C−H the bond order between the two carbon atoms is also 3, and the C−H bond order is 1. Bond order gives an indication to the stability of a bond....
for the molecule is 1.4.
Preparation
Boron monofluoride can be prepared by passing boron trifluorideBoron trifluoride
Boron trifluoride is the chemical compound with the formula BF3. This pungent colourless toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.-Structure and bonding:...
gas at 2000 °C over a boron rod. It can be condensed at liquid nitrogen temperatures (-196°).
Reactions
BF can react with itself to form polymers of boron containing fluorine with between 10 and 14 boron atoms. BF reacts with BF3Boron trifluoride
Boron trifluoride is the chemical compound with the formula BF3. This pungent colourless toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.-Structure and bonding:...
to form B2F4
Diboron tetrafluoride
Diboron tetrafluoride is a colorless gas. It can be formed by reacting boron monofluoride with boron trifluoride at low temperatures, taking care not to form higher polymers.-External links:*...
. BF and B2F4 further combine to form B3F5. B3F5 is unstable above -50° and forms B8F12. This substance is a yellow oil.
BF reacts with acetylenes to make the 1,4-diboracyclohexadiene ring system.
BF can condense with 2-butyne forming 1,4-difluoro-2,3,5,6-tetramethyl-1,4-diboracyclohexadiene.
Also it reacts with acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
to make 1,4-difluoro-1,4-diboracyclohexadiene.
Ligand
The first case of BF being a ligandLigand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
on a transition element was demonstrated in 2009 with the compound (C5H5)2Ru2(CO)4(μ-BF). The BF was bound to both ruthenium
Ruthenium
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russian scientist Karl Ernst Claus discovered the element...
atoms as a bridge. Vidovic
and Aldridge reacted NaRu(CO)2(C5H5) with (Et2O):BF3. Note that the BF was formed in place rather than added on.
Earlier in 1968 K. Kämpfer, H. Nöth, W. Petz, and G. Schmid claimed that Fe(BF)(CO)4 was formed in the reaction of B2F4 with Fe(CO)5
Iron pentacarbonyl
Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula 5. Under standard conditions Fe5 is a free-flowing, straw-colored liquid with a pungent odour. This compound is a common precursor to diverse iron compounds, including many that are useful in organic synthesis. Fe5 is...
, however this has not been reproduced.