The reaction of tetrachloro(2,4,6-tribromophenoxy)phosphorane, (TBPO)PCl4, with o-catechol yields dichloro(2,4,6-tribromophenoxy)(1,2-diphenoxy)phosphorane, (TBPO)(DP)PCl2. Quantitative 31P[1H] NMR spectroscopic studies demonstrate that this compound quantitatively converts secondary phosphonates into chlorophosphites. The chlorophosphites have been characterized by their reactions with tetracarbonylnorbornadienemolybdenum(0), Mo(CO)4(NBD), to form cis-Mo(CO)4(P(OR)2Cl)2. These reactions are also quantitative. The (TBPO)(DP)PCl2 has major advantages over other nonoxidative chlorinating agents. The compound can be prepared in quantitative yield from stoichiometric amounts of the starting materials, the synthesis of the (TBPO)(DP)PCl2 and the subsequent nonoxidative chlorination reaction can be carried out in one pot, and the byproduct of the reaction does not contain active chlorides. © 2002 Elsevier Science B.V. All rights reserved.