Abstract: An oligonucleotide which comprises at least one internucleotide linkage comprising a P—S—R bond and at least two nucleosides, wherein R corresponds to the formula (I) wherein A is a geminally substituted alkylene group, preferably CH2, X and Y are independently selected from S and O, and R0 is selected from the group consisting of optionally substituted carbon bonded organic residue, such as in particular optionally substituted alkyl or aryl, SRx, ORx and NRxRy wherein Rx and/or Ry are selected from H and organic residues and at least Rx is a substituent other than H. Another object of the invention is a sulfurizing agent useful for oligonucleotide manufacture and the manufacture thereof.