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If we consider the molecule B2H6 (diborane Figure 1), there are 12 valence electrons at our disposal for chemical bonding (B has 3, and H has 1, so 2xB + 6xH =12). Each terminal B–H bond is a standard vanilla two electron bond, and there are four of these, thus accounting for a total of eight electrons. This leaves a total of four electrons to share between the two bridging H atoms and the two B atoms. Consequently, two B–H–B bridging bonds are formed, each of which consists of two electrons (Figure 2), forming what are called threecenter- two-electron bonds (i.e., 3 atoms share 2 electrons) – sometimes called ‘banana’ bonds, as they are not linear but curved. Each B atom is, approximately, sp3 hybridized (hybridization is just a mathematical tool, so you can just as easily have s1.05p2.95 hybridized orbitals!), and if we consider just one of the B atoms, two of the four sp3 hybrid orbitals form s bonds to the terminal H atoms (1s orbitals). That leaves two B sp3 hybrid orbitals, one of which contains an electron, one of which is empty. For each bridge therefore, one sp3 orbital from each of the B atoms combines (Figure 3) with the 1s orbital of the bridging H atom to form three new molecular orbitals (MOs) – as always, n atomic orbitals (AO) form n MOs. One B atom gives its remaining valence electron to one bridge, and the other B atom gives to the other. Each bridge, therefore, has two electrons, which fill our new MO scheme starting with the lowest energy bonding MO.

If we consider the molecule B2H6 (diborane Figure 1), there are 12 valence electrons at our disposal for chemical bonding (B has 3, and H has 1, so 2xB + 6xH =12). Each terminal B–H bond is a standard vanilla two electron bond, and there are four of these, thus accounting for a total of eight electrons. This leaves a total of four electrons to share between the two bridging H atoms and the two B atoms. Consequently, two B–H–B bridging bonds are formed, each of which consists of two electrons (Figure 2), forming what are called threecenter- two-electron bonds (i.e., 3 atoms share 2 electrons) – sometimes called ‘banana’ bonds, as they are not linear but curved. Each B atom is, approximately, sp3 hybridized (hybridization is just a mathematical tool, so you can just as easily have s1.05p2.95 hybridized orbitals!), and if we consider just one of the B atoms, two of the four sp3 hybrid orbitals form s bonds to the terminal H atoms (1s orbitals). That leaves two B sp3 hybrid orbitals, one of which contains an electron, one of which is empty. For each bridge therefore, one sp3 orbital from each of the B atoms combines (Figure 3) with the 1s orbital of the bridging H atom to form three new molecular orbitals (MOs) – as always, n atomic orbitals (AO) form n MOs. One B atom gives its remaining valence electron to one bridge, and the other B atom gives to the other. Each bridge, therefore, has two electrons, which fill our new MO scheme starting with the lowest energy bonding MO.

full detail see this-http://voh.chem.ucla.edu/vohtar/fall03/classes/30B/pdf/diborane.pdf

full detail see this-http://voh.chem.ucla.edu/vohtar/fall03/classes/30B/pdf/diborane.pdf

it is called dimer bcoz, e.g B2H6 containstwo bridged four terminal hydrogens,resulting structure is called dimer of B2H6

it is called dimer bcoz, e.g B2H6 containstwo bridged four terminal hydrogens,resulting structure is called dimer of B2H6

it is called dimer bcoz, e.g B2H6 containstwo bridged four terminal hydrogens,resulting structure is called dimer of B2H6

it is called dimer bcoz, e.g B2H6 containstwo bridged four terminal hydrogens,resulting structure is called dimer of B2H6

it is called dimer bcoz, e.g B2H6 containstwo bridged four terminal hydrogens,resulting structure is called dimer of B2H6

it is called dimer bcoz, e.g B2H6 containstwo bridged four terminal hydrogens,resulting structure is called dimer of B2H6

A water molecule consists of two hydrogen atoms and one oxygen atom. The three atoms make an angle; the H-O-H angle is approximately 104.5 degrees. The center of each hydrogen atom is approximately 0.0957 nm from the center of the oxygen atom. The structure of a single water molecule is shown below: Picture credits Because oxygen is more electronegative than hydrogen (in other words, electrons tend to be in the neighborhood of the oxygen), the hydrogen atoms end up with a partial positive charge and the oxygen atom with a partial negative charge. This separation of charge produces a net dipole moment on the molecule; for the isolated water molecule this dipole moment is approximately 1.85 Debye units. This molecular structure leads to hydrogen bonding, which is a stabilized structure in which a hydrogen atom is in a line between the oxygen atom on its own molecule and the oxygen on another molecule. This picture shows a hydrogen-bonded structure between two water molecules: These hydrogen bonds, with their extra attractive energy, are the cause of many of the unusual properties of water, including its large heat of vaporization and its expansion upon freezing.

A water molecule consists of two hydrogen atoms and one oxygen atom. The three atoms make an angle; the H-O-H angle is approximately 104.5 degrees. The center of each hydrogen atom is approximately 0.0957 nm from the center of the oxygen atom. The structure of a single water molecule is shown below: Picture credits Because oxygen is more electronegative than hydrogen (in other words, electrons tend to be in the neighborhood of the oxygen), the hydrogen atoms end up with a partial positive charge and the oxygen atom with a partial negative charge. This separation of charge produces a net dipole moment on the molecule; for the isolated water molecule this dipole moment is approximately 1.85 Debye units. This molecular structure leads to hydrogen bonding, which is a stabilized structure in which a hydrogen atom is in a line between the oxygen atom on its own molecule and the oxygen on another molecule. This picture shows a hydrogen-bonded structure between two water molecules: These hydrogen bonds, with their extra attractive energy, are the cause of many of the unusual properties of water, including its large heat of vaporization and its expansion upon freezing.

v shape

v shape