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The synthesis of P-functionalized cycloheptatrienyl chelate complexes incorporating the linked cycloheptatrienyl–phosphane ligand [2-(diisopropylphosphanyl)phenyl]cycloheptatrienyl, o-iPr2P&z.sbnd;C6H4&z.sbnd;C7H6, is described. The ligand precursor [2-(cyclohepta-2,4,6-trienyl)phenyl]diisopropylphosphane (2b) can be obtained by addition of lithiated 2-BrC6H4PiPr2 (1b) to the tropylium cation C7H7+. On reaction with Mo(CO)6, the P-functionalized cycloheptatriene 2b acts as an eight-electron ligand to afford the cycloheptatriene–phosphane chelate complex [(o-iPr2P&z.sbnd;C6H4&z.sbnd;η6-C7H7)Mo(CO)2(P&z.sbnd;Mo)] (3b) as a single, chiral regioisomer, which undergoes clean hydride abstraction on treatment with (Ph3C)BF4. The resulting cationic complex 4b reacts with sodium bromide to yield the ‘chiral-at-metal’ complex [(o-iPr2P&z.sbnd;C6H4&z.sbnd;η7-C7H6)Mo(CO)Br(P&z.sbnd;Mo)] (5b). This 18-electron complex can be oxidized with 0.5 equivalent Br2 to give paramagnetic [(o-iPr2P&z.sbnd;C6H4&z.sbnd;η7-C7H6)MoBr2(P&z.sbnd;Mo)] (6b). 6b is a versatile starting material for the preparation of various cycloheptatrienyl–molybdenum complexes, which is exemplified by the isolation of the dialkyl complex [(o-iPr2P&z.sbnd;C6H4&z.sbnd;η7-C7H6)Mo(CH2SiMe3)2(P&z.sbnd;Mo)] (7b) upon reaction of 6b with Me3SiCH2MgCl. In addition, the X-ray crystal structures of 3b, 4b, 5b, 6b, and 7b are reported. [Copyright &y& Elsevier]