The reaction of (R2PCH2SiMe2)(2)NM ((PNPM)-M-R; R = Cy; M = Li, Na, MgHal, Ag) with L2ReOX3 [L-2 = (Ph3P)(2) or (Ph3PO)(Me2S); X = Cl, Br] gives (PNPCy)ReOX2 as two isomers, mer,trans and mer,cis. These compounds undergo a double Si migration from N to O at 90 degreesC to form (POPCy)ReNX2 as a mixture of mer,trans and fac,cis isomers. Additional thermolysis effects migration of CH3 from Si to Re, along with compensating migration of halide from Re to Si. DFT calculations on various structural isomers support the greater thermodynamic stability of the POP/ReN isomer vs PNP/ReO and highlight the influence of the template effect on the reactivities of these species.