Dedicated to Professor Jaromír Plešek on the occasion of his 80th birthday in recognition of his major contributions to cluster borane chemistry.The Brellochs method was utilized to gain access to the [closo-1-CB 9 H 10 ] -anion (1). Previous work describing the details of the synthesis of 1 via the [closo-2-CB 9 H 10 ] -anion (2) was brief and insufficient. Therefore, we report an optimized procedure for the synthesis of 1, the preparation of the unknown C-halogenated series using N-halosuccinimides and bis(benzenesulfonyl)fluoroamine, and the unknown C-methylated product using CH 3 I. NMR properties and regularities within the series were also investigated.Monocarbaborane anion [CB 9 H 10 ] -(1) 1 belongs to the group of anions of general formula [CB n H n+1 ] -, where the anionic charge is highly delocalized. These anions possess chemical, electrochemical and thermal stability; thus, they are useful in weakly coordinating and low-nucleophilic anion chemistry as were described by Reed and Strauss 2 . Out of this group, the [closo-1-CB 11 H 12 ] -anion is the most studied 3 because of its easy accessibility. However, new synthetic breakthroughs produced monocarbaboranes via Brellochs reactions 4-6 of aldehydes with nido-B 10 H 14 , starting an accelerated expansion in sub-icosahedral monocarbaborane chemistry and revealing compounds with highly desirable characteristics.