Boron forms a large number of hydries (in addition to dibroane). More than 25 neutral Boranes and a large number of borane anions have been prepared and characterized. We are only dealing with some very simple higher neutral Boranes. These are B₄H₁₀, B₅H₉, B₅H₁₁, B₆H₁₀ and B₁₀H₁₄. These can be classified into two categories based on their stoichiometry and structure.

1. Nido-Boranes : (B_nH_n+4)
                                                     B₂H₆,B₅H₉,B₆H₁₀ and B₁₀H₁₄

The word nido is derived from the Latin word meaning ‘nest’. So they have a nest like open structure.

2. Arachno-boranes : (BnHn+6)
                                                           B₄H₁₀,B₅H₁₁

The word orachno-means spider’s web. Their structure is open form both ends. In these compounds boron atoms occupy n contiguous corners of an (n + 2) cornered polyhedron.

Nomenclature
Boranes are usually named by indicating the number of B atoms with a Latin prefix and the number of H atoms by an Arabic number in parentheses.

B₂H₆_____ _ diborane (6)
B₄H_{10_______}tetraborane (10)
B₅H_{9___ _____}pentaborane (9)
B₅H_{11______ _}pentaborane (11)
B₆H10______ hexaborane (10)
B₁₀H₁₄_____  decaborane (14)

Preparation   
(1)    Tetraborane (10) (B₄H10) is best prepared by keeping B2H6 under pressure at 25⁰ for 10 days.

(2)    (i) pentaborane-9 (B₅H₉) is prepared by passing a 1:5 mixture of B₂H₆ and H₂ at below one atmospheric pressure through a furnace maintained at 250⁰ for 3 seconds.

(ii) Alternatively, B₅H₉ can be prepared by pyrolysing B₂H₆ for 2.5 days in hot/cold reactor at 180⁰/-80⁰.

(3)    Pentaborane-11 (B₅H₁₁) can be prepared in 70% yield by the reaction of B₂H₆ and B₄H₁₀ in a hot/cold reactor maintained at + 120⁰/ - 30⁰C.

(4)    Decaborane-14 (B₁₀H₁₄) is prepared by paralysis of B₂H₆ at 100-200⁰C in the presence of catalytic amounts of Lewis bases such as demethylether.

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