CARBENE COMPLEXES .22. PREPARATION, PROPERTIES AND STRUCTURES OF THE N,N-FUNCTIONALIZED BIS(AMINO)CARBENEMOLYBDENUM(0) CARBONYLS [MO(CO)4(CN(CH2CHCH2)(CH2)2N(CH2CHCH2))] AND [MO(CO)3(CN[(CH2)3PPH2](CH2)2N((CH2)3PPH2)]N

Treatment of 1,2-bis(gamma-diphenylphosphinopropylamino)ethane [obtained from 1,2-bis(allylamino)ethane and 2PPh2H and CH(NMe2)(OMe)2] yielded the electron-rich enetetramine =[C (RXCH2)2NR]2[R=(CH2)3PPh2] [abbreviated as L2(CH2)3PPh2]. Although L2All, the analogue in which R = CH2CH : CH2, is unknown, the carbenemolybdenum title compounds [Mo(CO)4(LAll)] (3) and -[Mo(CO)3{L(CH2)3PPh2}]n (4) have been prepared from [Mo(CO)6]: for 3 from CH(NMe2)(OMe)2 + [All(H)N(CH2)]2 and for 4 from L2(CH2)3PPh2. In 3 only one of the R groups behaves in a ligating mode. L(All) being a chelating ligand, 3 is thus a rare example of a metal complex having both carbene- and eta2-alkene-ligation and the first for molybdenum. The presumed polymeric structure of 4 is believed to arise from one of the P(III) sites behaving in a chelating fashion with the other in a bridging mode. Treatment of 3 with (CO)-C-13 stereoselectively gave the isotopomer in which a CO trans to a CO was displaced, the trans effect thus being parallel to the trans influence (X-ray data); a coproduct was cis-[(Mo(CO)4(CO)(LAll))-C-13]. Similarly, cis-[Mo(CO)4(LAll)(PEt3)] was the sole product of reaction between 3 and PEt3, which upon irradiation yielded fac- together with mer-[Mo(CO)3(LAll)(PEt3)]. Thermolysis of 3 afforded AllC : N(CH2)2NAll as the only organic product. The X-ray structure of 3 showed that the mutually trans Mo-CO bonds are significantly longer [av. 2.037(5) angstrom] than Mo-CO trans to carbene [1.984(4) angstrom] or alkene [1.975(5) angstrom], with Mo-C(carb) at 2.229(4) angstrom.