Weakly coordinative interaction between [Cu(4,4/sup '/-bipy)]2n2n+ and [(VO)(HPO/sub 4/)(H/sub 2/PO/sub 4/)]2n2n- chains forming a new 2-D layer bimetallic phosphate: [Cu(4,4/sup '/-bipy)(VO)(HPO/sub 4/)(H/sub 2/PO/sub 4/)]/sub 2/ (4,4/sup '/-bipy=4,4/sup '/-bipyridine)