The first four-coordinate methanediide/alkyl lutetium complex (BODDI)Lu2(CH2SiMe3)2(μ2-CHSiMe3)(THF)2 (BODDI=ArNC(Me)CHCOCHC(Me)NAr,Ar=2,6-iPr2C6H3) (1) was synthesized by a thermolysis methodology through α-H abstraction from a Lu–CH2SiMe3 group. Complex 1 reacted with equimolar 2,6-iPrC6H3NH2 and Ph2C O to give the corresponding lutetium bridging imido and oxo complexes (BODDI)Lu2(CH2SiMe3)2(μ2-N-2,6-iPr2C6H3)(THF)2 (2) and (BODDI)Lu2(CH2SiMe3)2(μ2-O)(THF)2 (3). Treatment of 3 with Ph2C O (4?equiv) caused a rare insertion of Lu–μ2-O bond into the C O group to afford a diphenylmethyl diolate complex 4. Reaction of 1 with PhN=C  O (2?equiv) led to the migration of SiMe3 to the amido nitrogen atom to give complex  (BODDI)Lu2(CH2SiMe3)2-μ-{PhNC(O)CHC(O)NPh(SiMe3)-κ3N,O,O}(THF) (5). Reaction of 1 with tBuN C formed an unprecedented product (BODDI)Lu2(CH2SiMe3){μ2-[η2:η2-tBuNC(=CH2)SiMe2CHC NtBu-κ1N]}(tBuNC)2 (6) through a cascade reaction of N C bond insertion, sequential cyclometalative γ-(sp3)-H activation, C C bond formation, andrearrangement of the newly formed carbene intermediate. The possible mechanistic pathways between 1, PhNCO, and tBuN C were elucidated by DFT calculations.