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

摘要

Addition of isonicotinic acid NCsH_4CO_2H(or isonicH)to [Pt(dppf)(MeCN)_2]~(2+)2OTr(dppf = l,L~1-bis(diphenyl-phosphino)ferrocene,OTf = triflate)affords a mixture of the homometallic molecular square [Pt_4(dppf)_4(mu-O_2CC_5H_4N)_4]~4+4OTf-,1 and its precursor intermediate [Pt(dppf)(TL~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(mu-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-HC1 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(mu-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.