Reactions of the dirhenium(III,III) complex cis-Re-2(mu-O2CMe)(2)Cl-4(H2O)(2) that lead to the dirhenium(III,II) complexes Re-2(mu-O2CMe)Cl-4(PR3)(2)and tetrarheniumcyclodiyne clusters of the type Re-4(mu-O)(4)Cl-4(PR3)(4)

The reaction of cis-Re-2(mu -O2CMe)(2)Cl-4(H2O)(2) 1 with P(C6H4OMe-p)(3) g ives the tetranuclear complex Re-4(mu -O)(4)Cl-4[P(C6H4OMe-p)(3)](4) 14 alo ng with the salt [(C6H4OMe-p)(3)PMe](2)Re2Cl8 15. Compound 14 is the first symmetrical, neutral, tetrarheniumcyclodiyne type cluster that contains pho sphine ligands. Complexes of this same type with PPh3 (16) and PMe2Ph (17) have been prepared by alternative methods but have poor solubility properti es. The paramagnetic complex Re-2(mu -O2CMe)Cl-4(PPh3)(2) 2, which is prepa red from 1 by reaction with PPh3, undergoes phosphine substitution reaction s when treated with dichloromethane solutions of other phosphines. Simple n on-redox reactions can occur upon reaction of 2 with monodentate and bridgi ng bidentate phosphines to afford complexes of the types Re-2(mu -O2CMe)Cl- 4(PR3)(2) [PR3=PBz(3) 3, P(C6H4OMe-p)(3) 4 or PMePh2 5] and trans-Re-2(mu - O2CMe)Cl-4(mu -PP)(2) [PP=dppm 9, Ph2PNHPPh2 10 or (Ph2P)(2)C=CH2 11]. Howe ver, reactions that lead either to reduction to dirhenium(II) complexes or Re-Re bond cleavage are encountered in the case of the reactions of 2 with PMePh2, PMe2Ph, PCy3 and dppe; these have led to the isolation of Re2Cl4(PM ePh2)(4) 6, Re2Cl4(PMe2Ph)(4) 7, mer-trans-ReOCl3(PCy3)(2) 8, alpha -Re2Cl4 (dppe)(2) 12, and trans-[ReO2(dppe)(2)]Cl 13. The structures of compounds 3 , 8, 13, 14 and 15 have been determined by X-ray crystallography.