Methylcobalamin (mecobalamin, mecbl, or meb12) is a cobalamin, a form of vitamin b12. it differs from cyanocobalamin in that the cyano at the cobalt is replaced with a methyl group. methylcobalamin features an octahedral cobalt(iii) centre and can be obtained as bright red crystals. from the perspective of coordination chemistry, methylcobalamin is notable as a rare example of a compound that contains metal-alkyl bonds. nickel-methyl intermediates have been proposed for the final step of methanogenesis. methylcobalamin is equivalent physiologically to vitamin b12, and can be used to prevent or treat pathology arising from a lack of vitamin b12 intake (vitamin b12 deficiency). methylcobalamin is also used in the treatment of peripheral neuropathy, diabetic neuropathy, and as a preliminary treatment for amyotrophic lateral sclerosis.