SYNTHESIS OF NOVEL DONOR-ACCEPTOR MANGANESE(I) COMPLEXES OF FERROCENYLACETYLENE - CRYSTAL-STRUCTURE OF [(C-5H-5)FE(C-5H-4) C-EQUIVALENT-TO-CMN(CO)(3)(PH2PCH(ME)CH2PPH2)] WHICH HAS POTENTIAL FOR 2ND-ORDER NONLINEAR OPTICS - COLBERT,MCB; EDWARDS,AJ; LEWIS,J; LONG,NJ; PAGE,NA; PARKER,DG; RAITHBY,PR (JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 1994)