Constructing homo- And hetero-metallic molecular topologies using pyridylcarboxylates as spacers: Preparation of a half-ring complex with active coordination sites

Abstract

Addition of isonicotinic acid NC 5H 4CO 2H (or isonicH) to [Pt(dppf)(MeCN) 2] 2+2OTf -- (dppf = l,1'-bis(diphenyl-phosphino)ferrocene, OTf = triflate) affords a mixture of the homometallic molecular square [Pt 4(dppf) 4(μ-O 2CC 5H 4N 4] 4+4OTf -, 1 and its precursor intermediate [Pt(dppf)(η 1- NC 5H 4CO 2H) 2] 2+2OTf -, 2. The latter captures [Pd(dppf)(MeCN) 2] 2+2OTf - to give a heterometallic square, [Pt 2Pd 2(dppf) 4(μ-O 2CC 5H 4N) 4] 4+4OTf -, 3. Slight skeletal modification of the ligand leads to different assemblies. This is illustrated by the addition of NC 5H 4CH 2CO 2H·HCl to [Pt(dppf)(MeCN) 2] 2+2OTf - to give [PtCl(dppf)(NC 5H 4CH 2CO 2H)] +OTf -, 4, which reacts with another equivalent of AgOTf to yield the dibridged complex [Pt 2(dppf) 2(μ-NC 5H 4CH 2CO 2) 2] 2+2OTf -, 5. All complexes, with the exception of 3, have been structurally characterized by single-crystal X-ray crystallography. Complexes 2 and 4 are potential precursors to further molecular topologies.