Hydrogen‐bonding motifs in the solid‐state structure of ferroceneboronic acid

At 180 K, the crystal structure of ferroceneboronic acid, [Fe(C 5 H 5 )(C 5 H 6 BO 2 )], consists of centrosymmetric [FcB(OH) 2 ] 2 dimers [Fc is (η 5 ‐C 5 H 5 )Fe(η 5 ‐C 5 H 4 )], formed by a pair of complementary O—H⋯O hydrogen‐bonding interactions [O⋯H 1.97 Å and O⋯O 2.806 (3) Å]. The remaining two O‐bound H atoms per [FcB(OH) 2 ] 2 moiety serve to link the dimeric units to adjacent dimers in a criss‐cross fashion, very similar to that between hydrogen‐bonded chains in solid Fe[η 5 ‐C 5 H 4 B(OH) 2 ] 2 .