Reaction of (TlNO3)-N-l and (C4H10N4)Pt-ll(mnt) or (C4H10N4)Pt-ll(dmg-H) [mnt = maleonitriledithiolate, dmg-H = dimethylglyoximate dianion] in dilute, aqueous KOH yielded adducts of Tl-l and the conjugate bases of the platinum(11) compounds. The compound Tl-l[(C4H9N4)Pt-ll(dmg-H)]center dot 5H(2)O forms as dimers with close Tl(l)center dot center dot center dot Pt-ll separations of 3.0843(5) angstrom, while Tl-l[(C4H9N4)Pt-ll(mnt)] has much longer Tl(l)center dot center dot center dot Pt-ll separations of 3.4400(2) angstrom and forms loosely associated, helical coordination polymers. The new compounds are compared with the red and yellow polymorphs of Tl-l[(C4H9N4)Pt-11(CN)(2)], and the influences of crystal packing forces, Coulombic interactions, and hydrogen bonding on supramolecular structures and Tl(l)center dot center dot center dot Pt-ll separations are discussed.