Tripodal bis(imidazole) thioether ligands, (N-methyl-4,5-diphenyl-2-imidazolyl)(2)C(OR)C(CH3)(2)SR' (BITOR,SR'; R = H, CH3; R' = CH3, C(CH3)(3), C(C6H5)(3)), have been prepared, offering the same N2S donor atom set as the Cu-M binding site of the hydroxylase enzymes, dopamine beta hydroxylase and peptidylglycine hydroxylating monooxygenase. Isolable copper(I) complexes of the type [(BITOR,SMe)Cu(CO)]PF6 (3a and 3b) are produced in reactions of the respective tripodal ligands 1a (R = H) and 1b (R = Me) with [Cu(CH3CN)(4)]PF6 in CH2Cl2 under CO (1 atm); the pyramidal structure of 3a has been determined crystallographically. The infrared (IR) nu(CO)'s of 3a and 3b (L = CO) are comparable to those of the Cu-M-carbonylated enzymes, indicating similar electronic character at the copper centers. The reaction of [(BITOH,SMe)Cu(CH3CN)]PF6 (2a) with dioxygen produces [(BITO,SOMe)(2)Cu-2(DMF)(2)](PF6)(2) (4), whose X-ray structure revealed the presence of bridging BIT-alkoxo ligands and terminal -SOMe groups. In contrast, oxygenation of 2b (R = Me) affords crystallographically defined [(BITOMe,SMe)(2)Cu-2(mu-OH)(2)](OTf)(2) (5), in which the copper centers are oxygenated without accompanying sulfur oxidation. Complex 5 in DMF is transformed into five-coordinate, mononuclear [Cu-II(BITOMe,SMe)(DMF)(2)](PF6)(2) (6). The sterically hindered BIT OR,SR' ligands 9 and 10 (R' = t-Bu; R = H, Me) and 11 and 12 (R' = CPh3; R = H, Me) were also prepared and examined for copper coordination/oxygenation. Oxygenation of copper(l) complex 13b derived from the BITOMe,SBu-t ligand is slow, relative to 2b, producing a mixture of (BITOMe,SBu-t)(2)Cu-2(mu-OH)(2)-type complexes 14b and 15b in which the -SBu-t group is uncoordinated; one of these complexes (15b) has been ortho-oxygenated on a neighboring aryl group according to the X-ray analysis and characterization of the free ligand. Oxygenation of the copper(I) complex derived from BITOMe,SCPh3 ligand 12 produces a novel dinuclear disulfide complex, [(BITOMe,S)(2)Cu-2(mu-OH)(2)](PF6)(2) (17), which is structurally characterized. Reactivity studies under anaerobic conditions in the presence of t-BuNC indicate that 17 is the result of copper(I)-induced detritylation followed by oxygenation of a highly reactive copper(I)-thiolate complex.