AbstractSeveral synthetic methods are used to prepare naphthalene‐based aromatic 1,2‐diselenoles. A new one‐pot synthesis starting from naphthalene is used to produce theknown compound naphtho[1,8‐c,d][1,2]diselenole (Se2naph).Friedel–Crafts alkylation is used on Se2naph to substitute either one tert‐butyl group to form 2‐tert‐butylnaphtho[1,8‐c,d][1,2]diselenole (mt‐Se2naph) or two tert‐butyl groups to form 2,7‐di‐tert‐butylnaphtho[1,8‐c,d][1,2]diselenole (dt‐Se2naph). Bromination of mt‐Se2naph results in dibromination of the naphthalene ring, rather than reaction at selenium, to give 4,7‐dibromo‐2‐tert‐butylnaphtho[1,8‐c,d][1,2]diselenole (mt‐Se2naphBr2). Reduction of the Se–Se bond in Se2naph, mt‐Se2naph, dibenzo[c,e][1,2]diselenine (dibenzSe2), or diphenyl diselenide (Se2Ph2) with LiBEt3 H, followed by in‐situ addition of [PtCl2{P(OPh)3}2] yields the four‐coordinate mono‐ and dinuclear platinum(II) bis(phosphite) complexes [Pt(Se2naph){P(OPh)3}2] (1), [Pt(mt‐Se2naph){P(OPh)3}2] (2), [Pt2(dibenzSe2)2{P(OPh)3}2] (3), cis‐[Pt(SePh)2{P(OPh)3}2] (4), and trans‐[Pt2(SePh)4{P(OPh)3}2] (5).